Het Departement Parasitologie verwerkte in 2002 de wetenschappelijke audits van het vorige jaar en de aanbevelingen van de Wetenschappelijke Raad van Advies in een nieuwe structuur. Zijn doel blijft het verwerven, verspreiden en toepassen van wetenschappelijke kennis over parasitaire aandoeningen bij de mens, in het bijzonder malaria, leishmaniase, slaapziekte en schistosomiase, en het versterken van de capaciteiten op dit vlak in ontwikkelingslanden. Het Departement streeft deze doelstellingen na via grensverleggend en toegepast onderzoek, postacademisch onderwijs en vorming, en wetenschappelijke ondersteuning aan instellingen en programmas met verwante doeleinden. Het zoekt daarbij ook naar internationale toegevoegde waarde en competitiviteit.
Met het nieuwe beleidsplan profileert het Departement Parasitologie zich duidelijker dan ooit op een beperkt aantal thematische en disciplinaire speerpunten, en streeft het naar optimale coherentie en synergie tussen de verschillende eenheden. Na vele jaren van verspreiding over verschillende gebouwen is nu ook de fysieke hergroepering van de verschillende eenheden in grondig vernieuwde laboratoria en kantoren een feit. De herstructurering, verjonging en herprofilering brachten duidelijk een nieuwe dynamiek op gang waarvan de eerste resultaten al merkbaar zijn.
Ons onderzoek naar malaria concentreert zich enerzijds op risicofactoren voor transmissie, morbiditeit, en resistentie tegen insecticiden en medicamenten, en anderzijds op aangepaste strategieën voor bestrijding en preventie.
Ook verwaarloosde ziekten zoals Leishmaniase en Trypanosomiase (slaapziekte) hebben onze volle aandacht, en kregen in 2002 een breder draagvlak door de oprichting van een interdepartementale werkgroep Neglected Diseases (zie Focus on). Deze leidde op korte termijn tot een betere samenhang tussen het biologische, klinische, epidemiologische en bestrijdingsgerichte onderzoek.
Onze moleculaire studies van het Leishmania-genoom brengen de aanpassing van deze parasieten aan uitwendige factoren, zoals medicamenteuze druk en specifieke vectoren, in kaart. De technieken leiden ook tot een betere diagnostiek en differentiatie van de leishmaniaparasiet, absolute prioriteiten voor het klinisch management en de epidemiologische bestrijding. De merkwaardige dynamische genomica van deze parasiet kunnen ook tot vernieuwende inzichten in de fundamentele biologie leiden.
Slaapziekte is de verwaarloosde ziekte bij uitstek. Het ITG is sinds vele jaren al een wereldwijde voortrekker in de ontwikkeling en productie van diagnostica voor het terrein. Nieuwe testen voor de diagnose, stadiumbepaling en follow-up van de patiënten zijn broodnodig en blijven een hoofdlijn in ons onderzoek. De fascinerende interactie trypanosoma-tseetseevlieg komt aan bod in een meer fundamenteel onderzoeksprogramma. Het Schistosoma-onderzoek richt zich vooral op het bestuderen van de ecologische en immunologische relatie tussen gastheer en parasiet, haar invloed op klinische en epidemiologische gevolgen, en de integratie van bestrijdingsprogrammas in de reguliere structuren van de volksgezondheid.
Deze thematische hoofdlijnen worden door de verschillende eenheden verder uitgewerkt, waarbij de departementale coherentie meer dan ooit voorop staat.
De Eenheid Entomologie bestudeert de malariavectoren met nadruk op de identificatie en karakterisering van Anophelesmuggen, de relatie met het milieu en de transmissiedynamica, resistentie tegen insecticiden en maatregelen voor vectorbestrijding. In 2002 konden we onze netwerkactiviteiten in Afrika en Zuidoost-Azië gevoelig versterken en uitbreiden. Samen met het Burundese Ministerie van Volksgezondheid en Artsen zonder Grenzen werkten we een strategie uit voor de preventie van epidemische malaria in de Centraal-Afrikaanse hoogvlakten. De Eenheid neemt deel aan baanbrekend fundamenteel onderzoek naar de interactie tussen gastheer en trypanosoma-parasieten, binnen een interuniversitair netwerk. Onze unieke tseetsee/trypsanosomakweek levert daarenboven het biologische materiaal aan voor dit onderzoek. De Eenheid werkt verder nauw samen met de Eenheid Epidemiologie en Bestrijding aan projecten in Vietnam, Burundi en Oeganda.
De Eenheid Epidemiologie en Bestrijding van Parasitaire Ziekten onderzoekt in Oeganda hoe de intensiteit van transmissie de verspreiding beïnvloedt van medicamenteuze resistentie van de malariaparasiet. Om deze groeiende problematiek aan te pakken testen we ook nieuwe combinatietherapieën uit in Burkina Faso, Zambia, Rwanda en Peru. We startten een nieuw netwerk voor onderzoek naar de preventie van malaria en bloedarmoede bij zwangere vrouwen en babys, onder meer via periodieke behandelingen in Malawi en Burkina Faso. In Vietnam rondden we een studie af over de epidemiologie van oerwoudmalaria.
De vroegere Eenheid Serologie vormde zichzelf om tot een nieuwe Eenheid Parasitaire Diagnostiek, die meer doelgericht zal werken op nieuwe diagnostische benaderingen van parasitaire ziekten bij de mens, in het bijzonder slaapziekte en leishmania. De omvangrijke routineproductie van de CATT (Card Agglutination Test for Trypanosomiasis), die inmiddels vrijwel alle bestrijdingsprogrammas in Afrika voorziet van de cruciale screeningkits, werd operationeel en financieel verzelfstandigd in een nieuwe interdepartementele dienst Toegepaste Technologie & Productie (TT&P). De Eenheid Parasitaire Diagnostiek kan zich terug op het onderzoek toespitsen. Voor slaapziekte zoeken we gericht naar nieuwe parasitologische, serologische, klinische en genetische merkers en hun toepassing in primaire diagnose, stadiumbepaling en follow-up bij de mens. Aansluitend onderzoeken we, bij gebrek aan een gouden standaard, nieuwe stochastische modellen voor de bepaling van diagnostische gevoeligheid en specificiteit. Het Departement Diergeneeskunde zal het onderzoek op de diagnostiek van dierlijke trypanosomiasen grotendeels overnemen, maar intense samenwerking en coördinatie blijven vanzelfsprekend
De vroegere Eenheid Protozoölogie vormde zichzelf om tot een nieuwe Eenheid Moleculaire Parasitologie. Prof. Dominique Le Ray ging met emeritaat na een lange en vruchtbare carrière en werd opgevolgd door Jean-Claude Dujardin. Op basis van de interne en externe audits beperkte ook deze eenheid het aantal onderzoekslijnen en bracht de productie en ontwikkeling van diagnostica, met name de Direct Agglutination Test (DAT) voor leishmania over naar de nieuwe productie-eenheid TT&P. Het belangrijkste thema wordt het Leishmania-genoom, met zowel fundamenteel onderzoek naar de genomische dynamiek als toegepast onderzoek naar de moleculaire detectie van resistentie tegen geneesmiddelen bij viscerale en mucocutane leishmaniasis. In 2002 pasten we de expertise ook succesvol toe op andere parasieten, in het bijzonder bij het al vermelde onderzoek naar de moleculaire diagnostiek en epidemiologie van medicamenteuze malariaresistentie. Dit is een goed voorbeeld van de vernieuwde synergie tussen de verschillende eenheden.
De Eenheid Humane Helminthologie is de opvolger van de Schistosomiasis Groep van de directeur, die in 2001-2002 geleidelijk geïntegreerd werd in het Departement Parasitologie, en nauw samenwerkt met de Eenheid Immunologie (Departement Microbiologie, Prof. Luc Kestens). Het onderzoek richtte zich in 2002 nog vooral op schistosomiasis, met als hoofdlijnen: de immuno-epidemiologie en de populatiedynamica van Schistosoma-infecties, en de integratie van bestrijdingsmaatregelen in de reguliere gezondheidsdiensten. In 2002 begon deze Eenheid ook andere domeinen binnen de helminthologie te verkennen, daarbij ook tegemoetkomend aan een toenemende vraag van binnen en buiten het Instituut. In de komende jaren zullen we onder meer, waar dit relevant is, in de institutionele samenwerkingsprogrammas van het ITG een medisch-helminthologisch luik uitbouwen. We zullen daarbij nauw samenwerken met de Eenheid Veterinaire Helminthologie, in het bijzonder over de humane component van de parasitaire zoönosen.
Het Departement Parasitologie bleef ook zeer actief in de diverse onderwijsprogrammas van het ITG, in de ontwikkeling van nieuwe richtingen aan de Universiteit Antwerpen, en in diverse internationale programmas voor vorming en capaciteitsversterking (zie hoofdstukken Onderwijs en Ontwikkelingssamenwerking).
|2. FOCUS ON: Interdepartementale onderzoeksgroep neglected diseases (IDND)
Neglected diseases is een brede noemer voor de tropische parasitaire aandoeningen die in het huidige toegepast biomedisch onderzoek dikwijls uit de boot vallen. Daardoor is er in de ziektebestrijding een acuut deficit ontstaan aan innoverende geneesmiddelen, diagnostica, of interventies in het algemeen. Sinds maart 2002 brengt een interdepartementale onderzoeksgroep neglected diseases (IDND) alle ITG-onderzoekers samen die binnen dit domein van de verwaarloosde ziekten werken. Op dit moment wordt vooral gewerkt op trypanosomiase en leishmaniase. Alle ITG-departementen zijn in de groep vertegenwoordigd.
WAAROM? De combinatie van deze multidisciplinaire expertise biedt betere garanties op pertinentie, complementariteit, coherentie en efficiëntie van het onderzoek.
HOE? De groep analyseert de prioriteiten en bepaalt een gezamenlijke onderzoeksstrategie. Via maandelijkse bijeenkomsten, maar ook ad hoc, wordt onderlinge steun verleend bij alle fases van het onderzoek : het ontwikkelen van onderzoeksvoorstellen, de uitvoering, de analyse en de presentatie ervan. Speciale aandacht gaat naar kwaliteitszorg, vlotte communicatie en continue vorming.
WAT? Het ITG heeft voor de periode 2001-2005 o.a. de strategische keuze gemaakt om te investeren in R&D van diagnostica voor deze verwaarloosde ziekten.
Het departement Diergeneeskunde verricht onderzoek op diagnose van dierlijke trypanosomiase en leishmaniase.
Het departement Parasitologie bezit een unieke kennis en ervaring wat betreft diagnose van trypanosomiase en leishmaniase (CATT, LATEX/Tbg, LATEX/IGM en DAT testen).
In beide departementen wordt fundamenteel moleculair biologisch onderzoek vertaald naar relevante klinische, diagnostische en epidemiologische toepassingen.
Het departement Volksgezondheid analyseert hoe deze ziekten op een al of niet geïntegreerde wijze kunnen worden aangepakt door de gezondheidsdiensten van de Derde Wereld, en verricht kosten-effectiviteitsanalyse van verschillende diagnostische strategieën. Er werd ook een methodologische bijdrage geleverd op het gebied van validatieonderzoek met behulp van mathematische modellering.
Het departement Klinische Wetenschappen ondersteunt de ontwikkeling van nationale referentielaboratoria, zoals het Nationaal Referentielabo voor diagnose van slaapziekte in het Institut de Recherches Biomédicales (INRB) te Kinshasa in de Democratische Republiek Kongo.
Door een betere coördinatie van al deze onderzoeksactiviteiten kunnen we onze slagkracht vergroten.
In 2002 werd een analyse gemaakt van de prioriteiten voor slaapziekteonderzoek in de D.R. Congo. Er werd een multidisciplinaire studie van het probleem Urbane slaapziekte in Kinshasa op touw gezet, die in januari 2003 van start gaat met financiering van DGOS (Raamakkoord). Een case-controlestudie over risicofactoren voor slaapziekte bij bewoners van Kinshasa werd opgestart. Daarnaast werd een strategie opgezet voor het verder uitbouwen van het INRB als referentiecentrum. Drie doctoraatsvoorstellen van Kongolese collegas werden ingediend en aanvaard. Er werd een globale strategie uitgewerkt voor R&D van diagnostica voor slaapziekte (V.Lejon, P.Büscher, ITG, Parasitologie), die werd voorgesteld aan WHO en CDC. Resultaten van onderzoek op slaapziekte en leishmaniase werden voorgesteld op congressen in Lissabon, Edinburg en Antwerpen. Een intranetsite werd ontwikkeld ten behoeve van de leden van de groep. De IDND-groep kreeg in 2002 het Legaat Broden ter erkenning en ondersteuning van zijn activiteiten.
Unit of Entomology
Identification and characterisation of malaria vectors in Southeast Asia
Information on population structure and gene flow provides insights into the potential spread of insecticide resistance in a vector population. Anopheles minimus A, a major malaria vector in this area, is the main target of vector control. In rural areas, An. minimus breeds along the banks of small clearwater streams, yet in the suburbs of Hanoi, northern Vietnam, an An. minimus population can be found whose immature stages develop in water tanks. This study uses allozyme data to assess the population structure of An. minimus A and to evaluate the taxonomic status of the urban An. minimus population from Hanoi. The population from the suburbs of Hanoi was identified as An. minimus A. Although significant genetic differentiation was observed between rural and urban An. minimus A populations, estimated gene flow indicated that they are not expected to differentiate substantially through genetic drift. Limited macro-geographical differentiation was observed between two rural populations at distances of more than 1000 km. Consequently, geographical distance is not the primary factor in differentiating An. minimus A populations having the typical breeding ecology. Furthermore, no genetic structuring was observed between adult mosquitoes having different behaviour. The macrogeographical population structure indicates that genes (e.g. genes associated with insecticide resistance) may spread over large areas. The presence of an urban An. minimus A population shows the ability of this species to adapt to anthropogenic environmental changes.
ITM promoter: M. Coosemans
ITM collaborators: W. Van Bortel, P. Roelants
External collaboration: Th. Backeljau (UA Antwerp and KBIN Brussels);L.D. Cong, H.D. Trung (National Institute of Malariology, Hanoi, Vietnam)
Monitoring insecticide resistance
Malaria vector control is primarily based on the use of bed nets impregnated with pyrethroids. The use of indoor residual spraying is limited to epidemic situations. Appropriate monitoring of vector resistance to insecticides is an integral component of planning and evaluation of insecticide use in malaria control programmes.
Pyrethroids and DDT, two important insecticides for vector control, block the nerve-impulse conduction by preventing the para-type sodium channel from returning to their closed-gated configuration after an action potential. A single mutation in the DIIS6 segment of the para-type sodium channel gene is the molecular basis for an important mechanism of resistance to pyrethroids and DDT, known as knockdown resistance (kdr). The sequence of the DIIS6 region of the para-type sodium channel gene has been determined for a limited number of susceptible specimens of the major malaria vectors of Southeast Asia (An. dirus, An. sundaicus, An. minimus) and Africa (An. gambiae, An. arabiensis and An. funestus). Sequence variation, between and within species, is further analysed. The frequency of the kdr mutation is being estimated in Uganda and Burundi. The unit is involved in the African network (WHO) for monitoring insecticide resistance. A new project on monitoring of insecticide resistance and mapping of malaria vectors in Southeast Asia (MALVECASIA) was started in 2002. More than 140 sites will be prospected in the region.ITM promoter: M. Coosemans
ITM collaborators: K. Verhaeghen, W. Van Bortel, P. Roelants
External collaborators: L.D. Cong, H.D. Trung (National Institute of Malariology, Hanoi, Vietnam); S. Doung, T. Sochanta (National Center for Malaria Control, Phnom Penh, Cambodia);
Ph. Samlane, K. Keokenchanh (Center of Malariology, Vientiane, Laos);V. Baimai (Mahidol University, Bangkok, Thailand); S. Manguin, C. Garros,I. Dusfour (IRD, Montpellier, France);
R. Harbach, Y. Linton (The Natural History Museum, London, UK);J. Hemingway, M. Coleman (Liverpool School of Tropical Medicine, Liverpool, UK); P. Guillet (WHO, Geneva)
Support: INCO-DC, IWT
Transmission study in seven sentinel sites in Uganda
This research is part of the project Intensity of malaria transmission and spread of antimalaria drug resistance, performed in close collaboration with the departments Unit of Epidemiology (Prof. DAlessandro). The aim is to determine whether the intensity of malaria transmission is an important factor influencing the spread of antimalarial drug resistance. Additional objectives are the distribution of the sibling species of the An. gambiae complex in Uganda and estimation of the frequency of the kdr gene involved in the pyrethroid insecticide resistance. Since May 2001, eleven entomological surveys have been performed at each study site. The molecular identification of the An. gambiae complex showed that mainly An. gambiae is present, while only a small percentage of An. arabiensis was detected. Sharp differences in vectorial densities according to study site were observed. The specimens of six sites for the first eight surveys have been processed for the detection of sporozoite antigens. One site can be classified as a high (>5 positive bites per night), two sites as medium (between 0.1 and 3 positive bites per night) and three sites as low transmission areas (between 0 and 0.09). Surprising was the detection of a high frequency of kdr-gene (about 25%) in the samples. The data will be further analysed in terms of dynamics of malaria transmission. Bioassays providing a broader picture on the level of insecticide resistance will be performed at the different sites. This is the first systematic research on malaria vectors in Uganda for many years, and it contributes significantly to capacity strengthening of the National Malaria Control Programme in entomological surveillance.
ITM promoter: M. Coosemans
ITM collaborators: U. DAlessandro , W. Van Bortel, P. Okello, K. Verhaeghen, A. Correwyn
External collaborators: A.Talisuna (MoH, Uganda); A. Byaruhanga (School of Medical Entomology and Parasitology)
Support: DGDC Framework Agreement
Prevention of malaria epidemics in African highlands
African highland regions are regularly exposed to serious outbreaks of malaria. These outbreaks are now an increasing problem due to population density in the highlands, increasing mobility, deteriorating health systems, absence of control programmes, drug resistance, political instability and global warming. Based on the experience in Burundi, it is clear that an outbreak is preceded by a progressive increase of malaria incidence. This spiral effect may take several years (2-5 years) before a threshold of parasite carriers is reached. If this occurs during the hottest season, a sudden increase of transmission, often for a short period, will follow resulting a few weeks later in epidemics. Drug resistance will accelerate this spiral effect. Vector control activities to control the epidemics were shown to have no impact because the short transmission period stopped just after the peak incidence. However, vector control could be effective in preventing malaria epidemics. Transmission is focalised in valley floors, while steep valley slopes are less exposed. With MSF, we developed a strategy for sustainable prevention of malaria epidemics for the province of Karuzi. Indoor spraying is targeted in space and time: houses located near the valley floors (25% of the population) are treated just before the hottest month of the year. One round per year is planned during a limited period of 3 years (first round in July 2002). The expected results will be a reduction in the vector population around the valley floors and a screen effect for the inhabitants living at higher altitudes. Transmission will be stopped and the parasite reservoir will decrease in a reversal of the spiral. After this intervention period, a good surveillance system based on malaria incidence data from the health services and regular estimation of the vector densities by more specialised teams are required to plan the next vector control intervention. An additional benefit of this control strategy will be reduction of selection of resistant parasites against the new drugs. This will have important benefits in reducing the future expenditure on drugs.
ITM promoter: M. Coosemans
ITM collaborators: U. DAlessandro, W. Van Bortel, P. Roelants
External collaborators: N. Protopopoff, P. Maes, L Walker, M. Van Herp (MSF); M. Barutwanayo (LMTC Burundi)
Institutional strengthening of the National Institute of Malaria,Parasitology and Entomology in Vietnam
The overall objective is to reduce the burden of parasitic diseases in Vietnam, Laos and Cambodia. Strengthening the institutional, scientific, technical and networking capacities of the national reference institutes will lead to the design of scientifically valid strategies for the control and surveillance of malaria and helminths. Malaria, once the major health problem, is under control in most of Vietnam thanks to tenacious efforts, but sustaining the success requires close surveillance and sophisticated research in human as well as in mosquito populations. Gradually, other parasitic diseases become prominent priorities, in particular helminthic infections such as cysticercosis, Asian flukes and intestinal nematodes. Moreover, a network has been established with the sister Institutes in Cambodia and Laos, leading to considerable interactions and exchanges. Further support and consolidation of this regional network for research and control of parasitic diseases is a major contribution to health and capacity strengthening in all three countries. In 2002, preliminary data were obtained on insecticide resistance and vector distribution in more than 40 sites. Training was provided in molecular biology. A validation study of the Ag-ELISA for the detection of circulating antigens used in diagnosing human cysticercosis is in progress. Morphological examination, enzyme electrophoresis and PCR techniques are being used for determining the different species of Taenia present in Northern Vietnam.
ITM promoter: M. Coosemans
ITM collaborators: W. Van Bortel, P. Roelants, U. DAlessandro, A. Erhart,P. Dorny, J. Brandt
External collaborators: L.D. Cong, H.D. Trung, N.D. Thang, L.X. Hung,N.V. De, H. Vien, D. Thach (NIMPE, Vietnam)
Characterisation of salivary gland proteins of the tsetse fly
The protozoan parasite Trypanosoma brucei spp. - the causative pathogen of sleeping sickness and animal trypanosomosis on the African continent - is cyclically transmitted by the obligate blood-feeding tsetse fly (Glossina spp). A crucial phase in the development of the parasite within the insect is localised in the flys salivary glands, where the trypanosomes attach to the epithelium and undergo a complex differentiation to the final infective metacyclic forms. These forms are embedded in the fly saliva and transmitted to a new host through the bite of the fly. In this study, we focused on the characterisation of salivary gland proteins that play a role in the development of the parasite within the tsetse fly and the vertebrate host. Genes that code for several novel salivary gland proteins were cloned and characterised: a secreted, heterogeneous protein of 125-140 kDa related to the 5- nucleotidase family and a 13 kDa membrane-bound protein that has significant similarities with proteins involved in protein-protein interactions. Both proteins are now being analysed for their possible involvement in trypanosome development in the flys salivary gland. Moreover, we observed an immunomodulatory activity of tsetse saliva in the vertebrate host. Saliva components inhibited the B-cell proliferation and cytokine-induction in the lymph nodes. This activity would be advantageous for the bloodsucking insect, since it suppresses the host antibody response to saliva components of the fly. No modulatory effect of saliva was observed on the establishment of an infection by metacyclic trypanosomes in the murine host.
ITM promoter: M. Coosemans
ITM collaborators: J. Van Den Abbeele, I. Tilmant, J. Van Hees
External collaborators: E. Pays (ULB, Brussels, Belgium); P. De Baetselier,
G. Caljon (VUB, Brussels, Belgium)
Support: Fund for Scientific Research Flanders (FWO), ITM
Unit of Parasite Diagnosis
Stage determination in sleeping sickness
Correct diagnosis of the disease stage in sleeping sickness is indispensable for treatment success. Drugs for the early stage (Pentamidine) are safe, but are ineffective in the meningo-encephalitic stage. Drugs for the meningo-encephalitic stage (mainly Melarsoprol) are highly toxic, and fatal adverse events occur in 5% of the patients.
Stage determination as prescribed by the World Health Organisation is based on examination of the cerebrospinal fluid for cell count, total protein concentration and presence of trypanosomes. These examinations have a limited sensitivity and specificity. Practical problems are encountered in execution of the examinations and interpretation of the results. Our laboratory is therefore investigating the neuro-inflammatory immune response of sleeping sickness patients to identify better parameters for stage determination and develop field-adapted tests.
We demonstrated that the meningo-encephalitic stage of the disease is characterised by a strong intrathecal IgM response. Detection of intrathecal IgM synthesis is technically not applicable in most African health centres. Based on the increased IgM concentration in the cerebrospinal fluid, which is a consequence of intrathecal synthesis, we developed a field test for IgM determination, LATEX/IgM. The value of detection of intrathecal IgM synthesis and LATEX/IgM in diagnosing central nervous system involvement could be demonstrated in early meningo-encephalitic stage patients. Positivity of one of both parameters was a risk factor for Pentamidine treatment failure in these patients. Our results also indicate that a number of patients who are actually treated with Melarsoprol may be treated with the safer Pentamidine.
It was also shown that patients in the meningo-encephalitic stage have increased interleukin-10 concentrations in the cerebrospinal fluid. However, the value of interleukin-10 detection for stage determination remains to be evaluated before field tests can be developed.
ITM promoter: P. Büscher
ITM collaborators: V. Lejon, T. Vervoort
External collaborators: D. Legros (EPICENTRE); C. Sindic (UCL); M. Richer (IMC); J.A. Ruiz (MSF-E); V. Jamonneau (IPR); P. Solano (IPR); P. Truc (IPR);
N. Djé (PRCT); F. Doua (PRCT); H. Reiber (University Göttingen); S. Bisser (IENT); L. Rosengren (University Göteborg); X. NSiesi (CDI-Bwamanda);C. Miaka (PNLTHA, Kinshasa)
Support: DGDC and others.
Characterisation of the invariable surface glycoproteins (ISGs) of salivarian trypanosomes
In order to replace native antigens in antibody detection diagnostics, research is performed on the Invariable Surface Glycoproteins (ISGs) of salivarian trypanosomes to identify putative diagnostic epitopes. There is now evidence that ISG 65 and ISG 75 are less invariable than believed, which could result in species-specific diagnostic tests.
ITM promoter: P. Büscher
ITM collaborators: F. Claes, J.C. Dujardin
External collaborators: B. Goddeeris (K.U. Leuven, Belgium)
Support: IWT, ILRI
Clinical trial on short pentamidine regimens for first-stage patients
Current treatment of first-stage T.b. gambiense sleeping sickness patients relies on seven daily injections with Pentamidine. Since there is evidence that fewer injections are equally curative, a clinical trial was set up to compare a 3-day course to the classical 7-day course. Our Unit is participating in this study to assist in correct stage determination for inclusion of the patients and to assess cure after treatment with the most sophisticated techniques.
ITM promoter: C. Miaka Mia Bilenge (PNLTHA, D.R. Congo)
ITM collaborators: P. Büscher, V. Lejon
External collaborator: S. Van Nieuwenhove (WHO-Afro)
Support: WHO TDR, CTB
Prospective cohort study of CATT performance
Control of sleeping sickness is mainly based on case detection and treatment of infected individuals. For early detection, the antibody detection test CATT is used to screen the population at risk. Some individuals are seropositive in CATT but remain unconfirmed parasitologically. Little is known about the incidence of overt sleeping sickness in those unconfirmed CATT positives, and the risk that healthy carriers act as a human reservoir is high. Our Unit is participating in these studies in D.R. Congo and Uganda which are intended to assess the rate of overt disease among CATT non-confirmed seropositives and CATT negatives. About 800 matched pairs are included in the study and followed up for 1 year. The results will be used to evaluate the need to treat serologically positive individuals as a control measure.
ITM promoter: C. Miaka Mia Bilenge (PNLTHA, D.R. Congo); F. Maiso (CNSSCP, Uganda)
ITM collaborators: P. Büscher, V. Lejon
External collaborators: S. Van Nieuwenhove (WHO-Afro); W. Van der Veken (CTB, Kinshasa)
Support: WHO TDR, CTB
National reference laboratory for human African trypanosomiasis in Kinshasa
The control programme for sleeping sickness in D.R. Congo suffers from insufficient technological capacity for quality control of field activities and for operational research. Currently they rely heavily on the back-up of ITM and proper training is provided for individual students at our Unit. In order to strengthen the capacity of the local control programme, the establishment of a reference laboratory has been initiated in Kinshasa at INRB and is currently in progress. Particular attention is being paid to establish serological screening with IFAT and to install a unit for local self-sustained production of the mini Anion Exchange Centrifugation Technique (mAECT), which is the most sensitive parasitological test for sleeping -sickness that can be carried out in the field.
ITM promoter: P. Büscher
ITM collaborator: T. Vervoort
External collaborators: C. Miaka Mia Bilenge (PNLTHA, D.R. Congo);J. Jannin, (WHO CTD)
Support: DGDC, WHO-Afro, CTB, WHO CTD
Establishment of a computerised cryobank for treatment-refractory trypanosomes
The increasing number of treatment-refractory cases in Uganda, Sudan and Angola is alarming. It appears that resistant strains are rare and scattered over different cryobanks. In addition, documentation on these strains is not digitised. The objectives of this project are:
1° To establish a central collection of all existing drug-resistant T.b. gambiense and T.b. rhodesiense strains, with copies at STIB, ITM and KETRI to avoid accidental losses. This collection will be available to other research groups.
2° To improve techniques for isolation of T.b. gambiense from refractory patients, particularly starting from their cerebrospinal fluid. Experiments by our Unit showed that the small tree rat Grammomys surdaster is highly susceptible to T.b. gambiense strains which otherwise grow very slowly in normal laboratory rats and mice. Based on this evidence, a breeding colony of Grammomys surdaster has been established at INRB in Kinshasa, D.R. Congo. This colony will be used to isolate new T.b. gambiense strains from refractory patients in D.R. Congo. If successful, colonies can be established in other Central African countries as well.
ITM Promoters: P. Büscher , R. Brun (STIB, Switzerland)
ITM collaborators: E. Magnus
External collaborators: J. NDungu (KETRI, Kenya); S. Karhemere (INRB, Kinshasa)
Support: WHO CTD
Characterisation of pathogenic Trypanosoma spp.
Currently, no parasitological or serological test can clearly distinguish between T. b. brucei, T. equiperdum and T. evansi infections in solipeds. The clinical signs of dourine, chronic surra and chronic nagana are very similar and prohibit correct differential diagnosis. Species-specific molecular tests to distinguish these three trypanosomes are not available, and the existing molecular trypanosome detection techniques have not yet been validated for diagnostic purposes. Studies on our Trypanozoon collection with newly-developed molecular techniques and T. evansi specific markers show that most T. equiperdum are identical to T. evansi, and that the remaining two strains cannot be distinguished from T. b. brucei. This finding can have important consequences on the current OIE-recommended strategy for dourine control.
ITM promoter: P. Büscher
ITM collaborator: F. Claes
External collaborators: B. Goddeeris (K.U.Leuven, Belgium); E. Agbo(ID-Lelystad, The Netherlands); P. Majiwa (ILRI)
Support: IWT, ILRI
Diagnosis of trypanosomiasis in small ruminants
Improved, more or less field-applicable diagnostic tests are still needed in animal trypanosomiasis control programmes and epidemiological studies. In the past, the project has generated serological (ELISA) and molecular (PCR) tests as well as a large collection of experimental infection sera from goats, sheep, cows and horses. One major problem encountered when developing serological tests for T. congolense and T. vivax is the production of large amounts of pure antigens, which are specific for each species. Crude antigens from in vitro cultures, such as used in the ELISA tests from IAEA, Vienna, are valuable, but some cross-reactivity is still observed. In connection with the following project, it will be possible to generate recombinant or synthetic peptides based on the species-specific proteases of the trypanosomes and to develop simple diagnostic tests with this material. The molecular diagnostics within this project are being developed in the Animal Health Department.
ITM promoter: S. Geerts
ITM collaborators: P. Büscher, V. Lejon, D. Geysen
External collaborator: S. Leak (ITC, The Gambia)
Immunological control of livestock trypanosomiases
Animal trypanosomiasis control is still heavily based on drug treatment. Trypanotolerant breeds exists and their phenotype seems to be related to their capacity to raise high levels of antibodies against trypanosome-released cysteine proteases. Previous vaccination trials with a T. congolense CP (congopain) have indicated that immunised animals develop a less severe disease than control animals. This opens up prospects for an anti-disease vaccine for T. congolense. Similar effects can be expected forT. vivax and T. brucei CPs. The ultimate goal of the project is to improve ruminant productivity in sub-Saharan Africa through limitation of trypanosome-induced pathology. Specific objectives are: to confirm and understand the role of trypanosome cysteine proteases (CPs) in pathology, to develop a novel strategy for improving health and productivity of ruminants exposed to trypanosomiasis, based on immunisation with trypanosome CPs, and to develop the diagnostic potential of CPs.
ITM promoter: E. Authié (CIRAD, France)
ITM collaborator: P. Büscher
External collaborators: A. Boulangé (ILRI, Nairobi); G. Lalmanach (Univ. de Tours, France); T. Baltz (Univ. de Bordeaux, France); M. Desquesnes (CIRDES, Burkina Faso); T. Coetzer (Univ. of Natal, South Africa)
Support: INCO DEV
Control and diagnosis of vector-borne diseases in livestock.
T. evansi is a widespread trypanosome with a huge range of hosts. Diagnosis is difficult due to low parasite loads and the fact that tests should preferably be applicable to all hosts (agglutination tests) and in the field. Thus far in the project, a CATT/T. evansi has been developed and validated and it is now being produced on demand. In addition, new tests, such as the LATEX/T. evansi, ELISA/T. evansi, PCR ESAG 6/7 and PCR RoTat 1.2, have been developed and tested on a small scale. The current objective is to replace native antigens by recombinant or synthetic -peptides in order to avoid the need for laboratory rodents in antigen -preparation and to increase the specificity of the tests.
ITM promoter: S. Morzaria (ILRI, Nairobi)
ITM collaborators: P. Büscher, F. Claes
External collaborators: P. Majiwa (ILRI); D. Verloo (CODA, Brussels)
Unit of Epidemiology and Control of Parasitic Diseases
Intensity of malaria transmission and spread of antimalarial drug resistance
The aim of this study is to determine whether the intensity of malaria transmission is an important factor influencing the spread of antimalarial drug resistance. The study began in 1999 and is being conducted in Uganda at 7 of the 8 sentinel sites of the East African Network for Monitoring Antimalarial Treatment (EANMAT). Each of them has been chosen according to different parameters, inter alia the intensity of malaria transmission. An annual cross-sectional survey has been carried out since 1999 on a random sample of the population, 250 individuals per site. Blood samples for parasitaemia, PCV and PCR analysis have been collected. A urine sample for the determination of chloroquine (CQ) and sulfadoxine-pyrimethamine (SP) use has also been collected. CQ resistance seems to spread faster at the extremes of the transmission intensity, while SP resistance spreads faster where the transmission is most intense. An entomological survey was started in 2001 at the 7 sentinel sites supervised by and with additional support from DGDC, in collaboration with the Unit of Entomology . The aim is to study and validate the relationship between the mean number of parasite clones found in the human hosts and the Entomological Inoculation Rate (EIR), i.e. the intensity of transmission.
Activities have also been extended to Rwanda, where the national malaria control programme is also part of the EANMAT. A study on the efficacy of amodiaquine (AQ) alone, AQ with artesunate and SP with artesunate has been carried out in 3 sentinel sites and involves 379 children with uncomplicated malaria. An additional study on the efficacy of AQ alone vs AQ + artesunate was completed in 2002.
ITM promoter: U. DAlessandro
ITM collaborators: M. Coosemans, J.C. Dujardin, C. Van Overmeir,N. Speybroeck
External collaborators: East Africa Network for Monitoring Antimalarial Treatment, Nairobi, Kenya; W. Watkins (Depart. of Pharmacology and Therapeutics, Liverpool University, UK);
T.K. Mutabingwa (National Institute for Medical Research, Amani, Tanzania & London School of Hygiene and Tropical Medicine, UK Gates Malaria Partnership, London, UK); E. Van Marck (University of Antwerp); P. Langi, (Ministry of Health, Kampala, Uganda); I. M. Hastings (Liverpool School of Tropical Medicine, UK); T. G. Egwang (Dept. of Parasitology, Med-biotech Laboratories, Kampala, Uganda); C. E. Rwagacondo (Programme de Lutte contre le Paludisme, Kigali, Rwanda)
Support: DGDC, Fund for Scientific Research Flanders (FWO)
Malaria morbidity in in Vietnam.
This project has been carried out in collaboration with the Unit of Entomology and the National Institute of Malariology, Parasitology and Entomology (NIMPE), Hanoi. Its main objective is to estimate the level of malaria morbidity at 4 sentinel sites with different patterns of malaria transmission and to link them with the corresponding entomological and ecological data. Active and passive detection of malaria cases has been performed for 2 years at 4 sentinel sites. Analysis of the data set is ongoing.
ITM promoter: U. DAlessandro
ITM collaborators: A. Erhart, M. Coosemans, C. Van Overmeir, N. Speybroeck
External collaborators: N.D. Thang, T.Q. Tuy, L.D. Cong (National Institute of Malariology, Parasitology and Entomology, Hanoi, Vietnam); N.Q. Hung (Institute for Malariology, Parasitology and Entomology (IMPE), Ho Chi Minh City, Vietnam)
Funding sources: DGDC
Several international agencies have devoted increasing efforts and resources to specific disease control programmes, regardless of the performances of the specific country health system and the sustainability of the interventions. The recent appearance of international funds and initiatives such as the Global Fund to Fight AIDS, TB and Malaria (GFATM) reflects this trend, with the risk of straining/overburdening health care systems. It is still unclear whether the GFATM will be able to collect and efficiently distribute the financial resources necessary for producing a significant impact. Even assuming the availability of adequate resources, a poorly performing health care system will not be able to use them optimally, and their impact might be less then expected, if not detrimental. The large amounts involved might cause some harm in already over-stretched health facilities. Therefore, a careful situation analysis of the performance of the health care systems is needed before investing large amounts of resources in specific disease control activities. Even the most cost-effective intervention will not have the expected results if access to good quality health care is not guaranteed to all strata of the local populations. A colloquium on these issues was organised in November 2002.
ITM promoter: U. DAlessandro
ITM collaborators: F. Moerman, A. Erhart, M. Coosemans, G. Kegels, J.P. Unger
External collaborators and institutes: C. Lengeler (Swiss Tropical Institute, Basel, Switzerland); J. Chimumbwa (National Malaria Control programme, Zambia); A. Talisuna (Resource Centre Ministry of Health, Uganda)
PREMA-EU, a network for malaria control during pregnancy
Malaria in pregnancy is an important preventable cause of low birthweight (LBW) and of severe maternal anaemia. Low birthweight is closely related to child survival, and severe maternal anaemia is an important contributor to maternal mortality and morbidity. Despite its importance, many countries have no policy or programme for controlling malaria in pregnancy. This is often due to a lack of clarity about what the policy should be, but also due to poor communication between those responsible for reproductive health and those responsible for malaria control. A network dealing with these issues, PREMA-EU, was set up at the end of 2001. The aim of PREMA-EU is to assist malaria-endemic countries in decreasing the burden of disease due to malaria and anaemia among pregnant women and babies living in endemic areas by promoting effective control strategies. Specific objectives are: (1) To review, synthesise and inform about the state of the art concerning malaria and anaemia in pregnancy, including burden of disease, programme strategies and research priorities. (2) To address specific technical and operational issues critical for malaria and anaemia control in pregnancy; (3) To promote the implementation of research findings into feasible interventions for malaria control in pregnant women. (4) To generate information that would help Roll Back Malaria (RBM) in formulating national and district-based -policies for the control of malaria in pregnant women.
ITM promoter: U. DAlessandro
ITM collaborators: F. Moerman, A. Erhart
External collaborators: B. Brabin, joint co-ordinator (Liverpool School of Tropical Medicine, Liverpool, UK);C. Menendez, P. Alonso (Hospital Clinic Universidad de Barcelona, Spain); D. Chandramoan (London School of Hygiene and Tropical Medicine, London, UK); J. Hill, S. Meek (UK Malaria Consortium - based jointly at Liverpool and London, UK); F. Nosten (Shoklo Malaria Research Unit, Hospital for Tropical Diseases, Mahidol University, Thailand); T. K. Mutabingwa (National Institute for Medical Research, Amani Medical Research Centre, Tanzania); O. Doumbo (Département dEpidémiologie de Affections, Faculté de Médecine, Bamako, Mali);C. Kankasa (Department of Paediatrics, University Teaching Hospital, Lusaka, Zambia); M. Meremikwu (Department of Paediatrics, University Teaching Hospital, Calabar, Nigeria); P. Langi (Malaria Control Unit, Ministry of Health, Kampala, Uganda)
Support: INCO-DEV Oct. 2001-Oct. 2004
Antimalarial treatment for pregnant women in rural Africa (DELIMAL)
Malaria during pregnancy is a major public health problem in endemic countries.
The administration of an effective antimalarial drug during pregnancy has a beneficial effect on the health of mother and child. However, few African countries have implemented programmes that have achieved good coverage, and little attention has been given to this problem. Two different approaches for delivering antimalarial intermittent treatment to pregnant women are being studied. One is based on a campaign promoting the use of sulfadoxine-pyrimethamine (SP) intermittent preventive treatment distributed through existing health services (Burkina Faso); the other on a village-based SP distribution system employing peer educators from an Adolescent Girls Literacy Programme (Malawi). In both countries, the effectiveness of the 2 approaches will be examined by following a large number of pregnant women. Endpoints will be the percentage of pregnant women having taken at least 2 intermittent treatments, peripheral parasitaemia during pregnancy and at delivery, placental malaria, maternal anaemia and mean and low birthweight.
An additional component on nutrition during pregnancy, funded by DGDC, will be grafted onto this project in 2003.
ITM promoter: U. DAlessandro
ITM collaborators: S. Gies, W. Schrooten, P. Kolsteren, D. Roberfroid
External collaborators: B. Brabin (Liverpool School of Tropical Medicine, Liverpool, UK); S.O. Coulibaly (Laboratoire National de Santé Publique, Ouagadougou, Burkina Faso); P. Kazembe (Lilongwe Central Hospital, Malawi); H. Tinto, N. Medas (Centre Muraz, Bobo Dioulasso, Burkina Faso)
Support: INCO-DEV Oct. 2002-June 2006; DGDC
Antimalarial drug combinations in HIV+ individuals with uncomplicated P. falciparum malaria in Zambia.
In Zambia, malaria remains the most important parasitic disease, while the HIV prevalence (which varies between 15% and 30% of the general population) is among the highest reported in Africa and the world. An interaction between malaria and HIV infection has been clearly shown for pregnant women; those who are HIV+ have a higher prevalence of peripheral parasitaemia and placental malaria. Furthermore, post-neonatal mortality is higher for infants whose mothers have both HIV infection and malaria. Recently, some interaction has also been reported for adults. The risk of clinical malaria is significantly higher in HIV+ adults and it increases with falling CD4 cell count. Therefore, in countries with high HIV prevalence like Zambia, HIV+ individuals with clinical malaria may represent a substantial part of patients attending health facilities. Considering that the clinical outcome of an antimalarial treatment is the result of the interaction between the drugs action and the immunological host response, HIV+ individuals having different degrees of immunological impairment might be less responsive to treatment. Zambia has chosen SP as first-line treatment in an interim phase. Coartem will then be implemented as first-line treatment in a few years. In 2002 we began preparing a clinical trial on SP vs. Coartem in HIV+ individuals with uncomplicated malaria. The trial should start in March 2003.
ITM promoter: U. DAlessandro
ITM collaborators: F. Moerman, L. Kestens, A. Buvé
External collaborators: R. Chilengi, R. Musonde (Tropical Disease Research Centre, Ndola, Zambia)
A randomised open hospital-based study to assess the safety and efficacy of dihydroartemisinin-piperaquine (Artekin) for the treatment of uncomplicated falciparum malaria in Iquitos, Peru.
This is part of a larger project of institutional collaboration between ITM and the Institute of Tropical Medicine Alexander von Humboldt in Lima. Peru has recently changed its first-line antimalarial drug to SP + artesunate in the north and to mefloquine and artesunate in Iquitos, in the Amazonian region. Among the major problems encountered in the implementation of this policy are the cost of the treatment and patient compliance. Artekin is a new antimalarial drug combination containing piperaquine and dihydroartemisinin (DHA).
Several factors make this combination a very exciting prospect for the future. This is a fixed dose co-formulation that will surely improve patient compliance. It is registered in Cambodia, China and Vietnam, which have decided that Artekin should represent half of all antimalarial treatments used in the country. Therefore, Artekin may become the most widely used combination in Southeast Asia. Moreover, Artekin is inexpensive compared to other combinations, such as mefloquine-artesunate, the first-line drug in Iquitos. It costs approximately 1US$ per adult treatment.
The study protocol has been written in collaboration with the Peruvian colleagues and the field work should start in 2003.
ITM promoter: U. DAlessandro
ITM collaborator: J.C. Dujardin
External collaborators: A. Llanos, D. Gamboa, C. Miranda (Institute of Tropical Medicine, Lima, Peru)
Unit of Molecular Parasitology
Molecular tools for monitoring emergence and spread of drug resistance among natural populations of Leishmania.
Leishmaniasis is a severe health problem in DCs and Europe. Pentavalent antimonials (SbV) will remain the first-line drug for the forthcoming years. Control is being challenged by increased SbV resistance. Our goal is to design molecular tools for detecting the emergence and spread of drug resistance in visceral and mucocutaneous leishmaniases. To achieve this, we will obtain samples from SbV susceptible and refractory patients (Nepal, Bolivia, Peru), identify molecular modifications associated with SbV resistance in field isolates, transfer this knowledge into molecular tools for drug resistance diagnosis, and define the population structure of sensitive and resistant isolates for understanding the epidemiological dynamics of drug resistance. Expected outputs are the collection of naturally-resistant parasites, knowledge about natural mechanisms generating SbV resistance and its transmission, PCR tools for preventing therapeutic failure and guidelines for their use in epidemiological surveillance.
ITM promoter: J.C. Dujardin
ITM collaborators: S. De Doncker, S. Decuypere ; M. Boelaert
External collaborators: S. Rijal (BPKIHS, Dharan, Nepal); J. Arevalo,A. Llanos-Cuentas (IMTAvH, Lima, Peru); H. Bermudez (CUMETROP, Cochabamba, Bolivia); S. Croft, V. Yardley (LSHTM, London, UK); F. Chappuis (HUG, Geneva, Switzerland)
Diagnostic and epidemiological markers for tracking of endemic and resurgent European leishmaniasis.
Visceral leishmaniasis is one of the most important vector-borne zoonoses in Southern Europe, and one for which there are no reliable, rapid, simple and sensitive typing methods. The current reference typing method, allozyme electrophoresis, is demanding and has low resolution power for genetic diversity and species taxonomy. We propose to develop new alternative molecular typing methods, based on clade-specific markers determined through DNA-based phylogenetic reconstructions. Phylogenies will be built from DNA sequences of genomic loci exhibiting a range of genetic variation from conserved to highly variable (microsatellites), and will be compared with allozyme-based phylogenies. Molecular typing procedures will be designed to fulfil the above-mentioned typing requirements. Applicability of the new markers will be evaluated for clinical typing of endemic and imported human and canine infections and for pilot studies of sympatric and allopatric populations. An electronic database for Leishmania typing data and strain information will be generated and will be made available via the Internet.
ITM promoter: M. Miles (LSHTM, London, UK)
ITM collaborators: J.C. Dujardin, S. De Doncker, W. Quispe
External collaborators: J. Alvar (ISCIII, Madrid, Spain); K. Soteriadou (Pasteur Institute, Athens, Greece); L. Campinho (IMT, Lisbon, Portugal); J.P. Dedet (Univ. Montpellier, France); G. Schönian (Inst. für Microbiologie, Berlin, Germany); J. Lukes (Academy of Science, Ceske Budejovice, Czech Republic)
The genetic polymorphism of Leishmania immunogenes and their relationship with clinical variability.
Tegumentary Leishmaniases affect 14 million people in tropical and subtropical areas of 8 countries in Latin America. The Leishmania parasites are transmitted to human (or other) hosts via the infected bite of phlebotomine sandflies of the genus Lutzomyia. Clinical manifestations are diverse, and range from a single lesion with spontaneous healing to mucocutaneous compromise. These different pathogenicities of the disease have been analysed in population studies, and in some cases were related to the genetic heterogeneity of parasites. However, all studies have focused on in vitro analyses, which are not representative of the parasite population present in a lesion. Moreover, most analyses are based in neutral characters such isoenzymes, RNA spacers, etc, which are not a priori related to virulence. Therefore, it will be more useful to explore the genetic polymorphism of Leishmania parasites, (i) directly in human tissues and (ii) using characters under immunological pressure and susceptible to adaptive variation. In the present project, we are seeking to analyse the genetic heterogeneity in human biopsies of major Leishmania immunogenes and their relationship with clinical variability.
ITM promoter: J.C. Dujardin
ITM collaborators: S. De Doncker, L. Garcia
External collaborators: H. Bermudez (Cumetrop, Cochabamba, Bolivia);
J. Arevalo (IMTAvH, Lima, Peru)
Support: TDR, Fund for Scientific Research Flanders (FWO) and BTC
Analysis of gene expression in the L. (V.) braziliensis life cycle by RNA fingerprinting.
In the context of clinical pleomorphism of American tegumentary leishmaniasis, Peruvian leishmaniases constitute an interesting model. Two species are most abundant in the country, L. (V.) braziliensis and L. (V.) peruviana. Interestingly, despite a very high genetic similarity, these two species cause quite different clinical patterns, severe mucosal lesions and benign cutaneous ulcers, respectively. In order to understand the high pathogenicity of L.(V) braziliensis and identify new genes associated with the infectivity of leishmania, mRNAs more abundant or specific to the infective stages of this species (metacyclic promastigotes, amastigotes) will be studied by Differential Display (DD) and characterised by sequencing. At the same time, differences in gene expression of the infective stages of L. (V.)braziliensis and L. (V.) peruviana will be explored.
ITM promoter: J.C. Dujardin
ITM collaborators: S. De Doncker, D. Gamboa
External collaborators: J. Arevalo (IMTAvH, Lima, Peru)
Support: TDR, DGDC and Unesco-LOréal
Institutional strengthening: Instituto de Medicina Tropical -Alexander von Humboldt.
As in all Andean countries, there is a high burden of poverty-related and infectious diseases in Peru, in both rural and urban areas. The Instituto de Medicina Tropical (ITMAvH) is a research and training institute for infectious and tropical diseases, a part of the Universidad Peruana Cayetano Heredia (UPCH), and is housed at the Hospital Nacional Cayetano Heredia in a large facility with outpatient and inpatient clinics. The Instituto has clinical and academic responsibilities in the Hospital and runs a series of biomedical laboratories within this hospital structure. Hence, the institute provides a unique potential for clinical research on tropical and infectious diseases, for which there is a huge and ever-growing need, both in its own right (basic pathophysiology, clinical epidemiology, therapeutic trials) and in order to provide a sound basis for laboratory research (immunology, molecular biology, diagnostics). After several joint research projects (primarily on leishmaniasis), the ITM and the ITMAvH have since 1998 intensified their collaboration in molecular biology, extended it to clinical research, and developed a concept for a broad and long-term institutional collaboration which can now be consolidated. Our aim is to improve the clinical management and control of infectious and tropical diseases in Peru and the Andean region through further strengthening ITMAvH clinical and biomedical research capabilities and upgrading its contribution as a national and international reference centre. The following issues will be supported: (1) Institutional policy, management and networking, (2) Human resources,(3) Logistic and techniques, (4) Training, research and actions.
ITM promoter: J.C. Dujardin
ITM collaborators: S. De Doncker , J. Van den Ende, E. Van den Enden,T. Verdonck, D. Swinne, U. DAlessandro, M. Coosemans, K. Polman,F. Portaels, G. Vanham, M. Boelaert
External collaborators: J. Arevalo, E Gotuzzo, D. Gamboa, B. Bustamante,H. Guerra, P. Ventosilla, I. Best (IMTAvH, Lima, Peru)
Unit of Helminthology
Epidemiology and control of schistosomiasis in northern Senegal
Over the past decade, northern Senegal has been confronted with a severe outbreak of Schistosoma infection following the construction of a dam on the Senegal river.
From early on we have been involved in the development, implementation and evaluation of integrated intervention strategies through the regular health services to control the epidemic. As the epidemic evolves towards endemicity, we are monitoring the evolution of clinical pathology, community morbidity and public health impact of S. mansoni infection. We are also using the evolution of the epidemic to investigate fundamental questions about the nature of resistance to Schistosoma infections (see below). We also focus on a few specific questions that have remained or emerged during the follow-up of control results so far. Despite the integrated control programme, an increasing number of advanced clinical cases (hepatosplenic disease, hematemesis) are being reported. Clinical and epidemiological studies are planned to document the size and nature of this problem and to investigate possible causes. The capacity to clinically manage these cases throughout the health system will also be strengthened. Moreover, it has proven very difficult to alter human behaviour in order to reduce exposure and contamination, despite intensive health information, education, water supply and sanitation. Thus it appears necessary to better understand the human aspects of transmission; in-depth studies on the ins and outs of water contact behaviour and the determinants of faecal contamination are in progress (see below).
ITM promoter: B. Gryseels
ITM collaborators: K. Polman, S. Sow, L. Kestens
External collaborators: A. Mbaye (Région Médicale de St. Louis, Senegal); L. Mbow, Y. Gaye (Health Services of Northern Province, Senegal); S. de Vlas, M. Van der Werf (Dept. of Public Health, Erasmus MC, University Medical Centre Rotterdam, The Netherlands)
Support: DGDC, European Union
Human behaviour and Schistosoma mansoni infection in northern Senegal: studies on water contact and contamination of streams
Human contact with water infested with cercariae and contamination of water harbouring snail intermediate hosts with excreta containing schistosome eggs are two crucial parts of the schistosomiasis transmission cycle. However, the precise mechanisms and importance of a number of factors in the underlying transmission dynamics are still unknown. Data assessment, analysis and interpretation are notoriously difficult in studies on human water contact. In northern Senegal, we have collected both quantitative (by direct observations) and qualitative (by questionnaires) water contact data, and both methodologies are presently being evaluated and compared. Attempts are being made to translate these data into a so-called exposure index, to be used and validated in our immuno-epidemiological studies on age-related resistance against schistosomiasis. Moreover, the socio-economic aspects (e.g. occupation) of human water contact behaviour will be investigated. The way in which schistosome eggs reach the water is probably the least studied and understood part of the schistosomiasis transmission cycle. For S. haematobium it is plausible that people urinate directly into the water. For S. mansoni, however, defecation directly into the water is considered to be less important, and other ways of contamination of water with S. mansoni eggs have to be identified. In this project, we seek to assess how (much) faecal material with (viable) schistosome eggs reaches the water, in order to obtain a quantification of each potential source of viable eggs to the contamination of water bodies. This year we carried out a pilot study in which different ways of collecting quantitative data on water contamination were tested. Next year, the main study will be performed.
Both studies will contribute to a better understanding of schistosomiasis transmission dynamics, with the final aim of identifying and recommending more appropriate and sustainable strategies for environmental control of transmission.
ITM promoter: B. Gryseels
ITM collaborators: S. Sow, K. Polman
External collaborators: S. De Vlas (Dept. of Public Health, Erasmus MC, University Medical Centre Rotterdam, The Netherlands)
Support: NWO/WOTRO, DGDC
Immunity and resistance in human schistosomiasis: age or experience?
The aim of this project is to understand the nature of immune responses to schistosome infections, in particular whether the drop in intensity of infection that occurs as adolescents become adult is due to their increased experience of infection, or a phenomenon related to age itself: the age or experience? question. This question is fundamental to understanding the host-parasite relation, with major implications for control, immunology and vaccine development. We also investigate whether and which underlying immune responses may cause these differences between age groups. As we work in an epidemic focus of S. mansoni infection in Senegal, where everybody has been exposed for the same number of years, age can be exceptionally dissociated from history of exposure, unlike in endemic foci.
Results so far suggest that intrinsic age-related factors are the main cause of adult resistance to S. mansoni infection, although children do seem to develop acquired immune responses that protect them from all too heavy worm burdens until adult resistance takes over. Our immunological studies have addressed possible mechanisms of such inherently age-dependent resistance. The data reveal that, amongst other observations, there are indeed differences in the schistosome antigen specific cellular responses of adolescents and adults. It seems that a childhood strategy to challenge with S. mansoni antigen of whatever level may be to down-regulate immune responses with IL-10. Adults respond with a more typical T-cell response: those with high intensities of infection with a classical type-2 response (both IL-4 and IL-5) and those with a low intensity of infection with a type-1 response (IFN). However, this is still a very preliminary idea that needs further investigation.
That age itself should alter an immune response suggests that the endocrine system is directing the immune system to some extent. Steroids such as DHEA (dehydroepiandrosterone) are crucial for the regulation of T cell maturation into specific subpopulations such as Th1 and Th2. Studies on this hormone as a correlate of resistance are ongoing. Also, new protocols have been developed using ELISPOT to study schistosome antigen-specific cellular immune responses at the single cell level. Further testing and application of this technique under field conditions in Senegal are planned for 2003.
ITM promoters: B. Gryseels, L. Kestens
ITM collaborators: J. Scott, K. Vereecken, K. Polman, D. Berkvens
External collaborators: A. Mbaye (Région Médicale de St. Louis, Senegal); J. Vercruysse (Laboratory of Parasitology, Faculty of Veterinary Medicine, University of Ghent); S. de Vlas (Dept. of Public Health, Erasmus MC, University Medical Centre Rotterdam, The Netherlands)
Support: Fund for Scientific Research Flanders (FWO), DGDC
Buruli Ulcer and schistosomiasis in Bas-Congo: a study on epidemiological and environmental links between the two diseases
Buruli ulcer (BU) is the most prevalent mycobacterial disease in tropical areas after tuberculosis and leprosy, causing serious deformities and disability. However, many aspects of the disease are still unknown.
Although BU and schistosomiasis are found in the absence of one another, there are close epidemiological parallels between the two diseases, suggesting that schistosomiasis could be a possible risk factor for BU, and/or that they may at least share some environmental risk factors. For example, both diseases are associated with tropical areas, occur in close proximity to bodies of water, and have a typical focal distribution. BU is most frequent in children under the age of 15, the same age group that hosts the greatest schistosome burdens. Our first collaborative study in Benin on infection with Schistosoma haematobium as a potential risk factor for BU revealed no association between the presence of BU and S. haematobium infection. On the other hand, 40% of BU cases with osteomyelitis were positive for S. haematobium infection, compared to 0% with other forms of the disease. Concurrent S. haematobium infection may thus be associated with severe disease. Transmission of schistosomiasis requires contact with water harbouring snail intermediate hosts, which release infective cercariae that penetrate the human skin. Transmission of BU is still an area of ongoing research, but is suggested to occur by subcutaneous infection with M. ulcerans, initiated by skin trauma. Recently, some Bulinus snails (the intermediate host of S. haematobium) were found positive for M. ulcerans by PCR. Thus it may be that the cercariae act as transport hosts and take the mycobacteria through the skin as they invade the human host. This year we started a second collaborative study in D.R. Congo, a country with highly endemic areas for both diseases, to further investigate potential links. Results are expected next year. The latter study also has the underlying aim to document the occurrence and transmission of schistosome infections as such, and to assist the regional health services in building up capacity to investigate and control the disease.
ITM promoters: B. Gryseels, F. Portaels
ITM collaborators: K. Polman, P. Suykerbuyk (student)
External collaboration: J. Lokombe (Service de Parasitologie, Institut Nationale de Recherche Biomédicale (INRB), Kinshasa, D.R. Congo); D. Phanzu,E. Bafende (Institut Médical Evangélique (IME), Kimpese, D.R. Congo)
|Publications in international peer-reviewed journals
Bisser S, Lejon V, Preux PM, Bouteille B, Stanghellini A, Jauberteau MO, Büscher P, Dumas M. Blood-cerebrospinal fluid barrier and intrathecal immunoglobulins compared to field diagnosis of central nervous system involvement in sleeping sickness. J Neurol Sci 2002; 193: 127-135.
Boelaert M, Le Ray D, Van der Stuyft P. How better drugs could change kala-azar control; lessons from a cost-effectiveness analysis. Trop Med Int Health 2002; 7: 955-959.
Chappuis F, Pittet A, Bovier PA, Adams K, Godineau V, Hwang SY, Magnus E, Büscher P. Field evaluation of the CATT/Trypanosoma brucei gambiense on blood-impregnated filter papers for diagnosis of human African trypanosomiasis in southern Sudan. Trop Med Int Health 2002; 7: 942-948.
Claes F, Verloo D, de Waal DT, Urakawa T, Majiwa P, Goddeeris BM, Büscher P. Expression of RoTat 1.2 cross-reactive variable antigen type in Trypanosoma evansi and T. equiperdum. Ann NY Acad Sci 2002; 969: 174-179.
Couvreur B, Wattiez R, Bollen A, Falmagne P, Le Ray D, Dujardin JC. Eubacterial HsIV and HsIU subunits homologs in primordial eukaryotes. Mol Biol Evol 2002; 19: 2110-2117.
Dujardin JC, Victoir K, De Doncker S, Guerbouj S, Arévalo J, Le Ray D. Molecular epidemiology and diagnosis of Leishmania: what have we learnt from genome structure, dynamics and function? Trans R Soc Trop Med Hyg 2002; 96(Suppl.1): S81-S86.
Erhart A, Dorny P, Nguyen Van De, Ha Viet Vien, Dang Cam Thach, Nguyen Duy Toan, Le Dinh Cong, Geerts S, Speybroeck N, Berkvens D, Brandt J. Taenia solium cysticercosis in a village in northern Viet Nam: seroprevalence study using an ELISA for detecting circulating antigen. Trans R Soc Trop Med Hyg 2002; 96: 270-272.
Faye D, Osaer S, Goossens B, Van Winghem J, Dorny P, Lejon V, Losson B, Geerts S. Sus-ceptibility of trypanotolerant West African Dwarf goats and F1 crosses with the susceptible Sahelian breed to experimental Trypanosoma congolense infection and interactions with helminth infections and different levels of diet. Vet Parasitol 2002; 108: 117-136.
Henriksson J, Dujardin JC, Barnabé C, Brisse S, Timperman G, Venegas J, Pettersson U, Tibayrenc M, Solari A. Chromosomal size variation in Trypanosoma cruzi is mainly progressive and is evolutionarily informative. Parasitology 2002; 124: 277-286.
Holland WG, Thanh NG, My LN, Magnus E, Verloo D, Büscher P, Goddeeris B, Vercruysse J. Evaluation of whole fresh blood and dried blood on filter paper discs in serological tests for Trypanosoma evansi in experimentally infected water buffaloes. Acta Trop 2002; 81: 159-165.
Legros D, Ollivier G, Gastellu Etchegorry M, Paquet C, Burri C, Jannin J, Büscher P. Treatment of human African trypanosomiasis; present situation and needs for research and development. Lancet Infect Dis 2002; 2: 437-440.
Lejon V, Büscher P. Le diagnostic de stade dans la maladie du sommeil: vers une nouvelle approche. Bull Soc Pathol Exot 2002; 95: 337-339.
Lejon V, Lardon J, Kenis G, Pinoges L, Legros D, Bisser S, NSiesi X, Bosmans E, Büscher P. Interleukin (IL)-6, IL-8 and IL-10 in serum and CSF of Trypanosoma brucei gambiense sleeping sickness patients before and after treatment. Trans R Soc Trop Med Hyg 2002; 96: 329-333.
Lejon V, Legros D, Richer M, Ruiz JA, Jamonneau V, Truc P, Doua F, Djé N, NSiesi FX, Bisser S, Magnus E, Wouters I, Konings J, Vervoort T, Sultan F, Büscher P. IgM quantification in the cerebrospinal fluid of sleeping sickness patients by a latex card agglutination test. Trop Med Int Health 2002; 7: 685-692.
Magnus E, Lejon V, Bayon D, Buyse D, Simarro P, Verloo D, Vervoort T, Pansaerts R, Büscher P, Van Meirvenne N. Evaluation of an EDTA version of CATT/Trypanosoma brucei gambiense for serological screening of human blood samples. Acta Trop 2002; 81: 7-12.
Manguin S, Kengne P, Sonnier L, Harbach RE, Baimai V, Trung HD, Coosemans M. SCAR markers and multiplex PCR-based identification of isomorphic species in the Anopheles dirus complex in Southeast Asia. Med Vet Entomol 2002; 16: 46-54.
Manguin S, Mouchet J, Coosemans M. Identification moléculaire despèces jumelles danophèles: exemple des complexes Anopheles minimus et Anopheles dirus vecteurs majeurs du paludisme en Asie du sud-est. Méd Trop 2001; 61: 463-469.
Mutabingwa TK, Watkins WM, DAlessandro U. Monitoring of drug-resistant malaria in Africa [letter]. Lancet 2002; 360: 875.
Polman K, Stelma FF, Le Cessie S, de Vlas SJ, Falcao Ferreira STM, Talla I, Deelder AM, Gryseels B. Evaluation of the patterns of Schistosoma mansoni infection and re-infection in Senegal, from faecal egg counts and serum concentrations of circulating anodic antigen. Ann Trop Med Parasitol 2002; 96: 679-689.
Radwanska M, Chamekh M, Vanhamme L, Claes F, Magez S, Magnus E, De Baetselier P, Büscher P, Pays E. The serum resistance-associated gene as a diagnostic tool for the detection of Trypanosoma brucei rhodesiense. Am J Trop Med Hyg 2002; 67: 684-690.
Radwanska M, Claes F, Magez S, Magnus E, Perez-Morga D, Pays E, Büscher P. Novel primer sequences for polymerase chain reaction-based detection of Trypanosoma brucei gambiense. Am J Trop Med Hyg 2002; 67: 289-295.
Radwanska M, Magez S, Perry-OKeefe H, Stender H, Coull J, Sternberg JM, Büscher P, Hyldig-Nielsen JJ. Direct detection and identification of African trypanosomes by fluorescence in situ hybridization with peptide nucleic acid probes. J Clin Microbiol 2002; 40: 4295-4297.
Solano P, Jamonneau V, NGuessan P, NDri L, Dje NN, Miezan TW, Lejon V, Büscher P, Garcia A. Comparison of different DNA preparation protocols for PCR diagnosis of human African trypanosomiasis in Côte dIvoire. Acta Trop 2002; 82: 349-356.
Sow S, de Vlas SJ, Engels D, Gryseels B. Water-related disease patterns before and after the construction of the Diama dam in northern Senegal. Ann Trop Med Parasitol 2002; 96: 575-586.
Talisuna OA, DAlessandro U. Malaria transmission, antimalarial-drug use, and resistance: a reply [letter]. Trans R Soc Trop Med Hyg 2002; 96: 704.
Talisuna AO, Kyosiimire-Lugemwa J, Langi P, Mutabingwa TK, Watkins W, Van Marck E, Egwang T, DAlessandro U. Role of the pfcrt codon 76 mutation as a molecular marker for population-based surveillance (CQ)-resistant Plasmodium falciparum malaria in Ugandan sentinel sites with high CQ resistance. Trans R Soc Trop Med Hyg 2002; 96: 551-556.
Talisuna AO, Langi P, Bakyaita N, Egwang T, Mutabingwa TK, Watkins W, Van Marck E, DAlessandro U. Intensity of malaria transmission, antimalarial-drug use and resistance in Uganda: what is the relationship between these three factors? Trans R Soc Trop Med Hyg 2002; 96: 310-317.
Tinto H, Zoungrana EB, Coulibaly SO, Ouedraogo JB, Traoré M, Guiguemde TR, Van Marck E, DAlessandro U. Chloroquine and sulphadoxine-pyrimethamine efficacy for uncomplicated malaria treatment and haematological recovery in children in Bobo-Dioulasso, Burkina Faso, during a 3-year period 1998-2000. Trop Med Int Health 2002; 7: 925-930.
Truc P, Lejon V, Magnus E, Jamonneau V, Nangouma A, Verloo D, Penchenier L, Büscher P. Evaluation of the micro-CATT, CATT/Trypanosoma brucei gambiense, and LATEX/T. b. gambiense methods for serodiagnosis and surveillance of human African trypanosomiasis in West and Central Africa. Bull World Health Organ 2002; 80: 882-886.
Van Bortel W, Sochanta T, Harbach RE, Socheat D, Roelants P, Backeljau T, Coosemans M. Presence of Anopheles culicifacies B in Cambodia established by the PCR-RFLP assay developed for the identification of Anopheles minimus species A and C and four related species. Med Vet Entomol 2002; 16: 329-334.
Van der Werf MJ, de Vlas SJ, Looman CWN, Nagelkerke NJD, Habbema JDF, Engels D. Associating community prevalence of Schistosoma mansoni infection with prevalence of signs and symptoms. Acta Trop 2002; 82: 127-137.
Van der Werf MJ, Mbaye A, Sow S, Gryseels B, de Vlas SJ. Evaluation of staff performance and material resources for integrated schistosomiasis control in Northern Senegal. Trop Med Int Health 2002; 7: 70-79.
Vickerman K, Le Ray D, Hoef-Emden K, De Jonckheere J. The soil flagellate Proleptomonas faecicola: cell organisation and phylogeny suggest that the only described free-living trypanosomatid is not a kinetoplastid but has cercomonad affinities. Protist 2002; 153: 9-24.
Victoir K, Dujardin JC. How to succeed in parasite life without sex? Asking Leishmania. Trends Parasitol 2002; 18: 81-85.
|Other publications and abstracts
Coosemans M, Protopopoff N, Barutwanayo M, Maes P, Van Herp M. Control and prevention of epidemics in African highlands: an important challenge [abstract]. Acta Trop 2002; 83(Suppl.1): S48, Abstract Nr.MOPS041.
DAlessandro U, Moerman F. Methods to measure haemoglobin in field conditions. EANMAT Newsl 2002; 5(1): 4-5.
De Vlas SJ, Danso-Appiah A, Scott JT. Can transmission of intestinal schistosomiasis be influenced by reducing population egg output through chemotherapy? [abstract]. Acta Trop 2002; 83(Suppl.1): S51-52, Abstract Nr.TUPS007.
Dujardin JC, Victoir K, Kindt A, Garcia L, Llanos-Cuentas A, Bermudez H, Arevalo J. Molecular epidemiology of American tegumentary leishmaniasis : direct species identification in human tissues [abstract]. Acta Trop 2002; 83(Suppl.1): S56, Abstract Nr.TUPS020.
Erhart A, DAlessandro U. Malaria vaccines: a brief overview. Doct Afr 2002; 24(4): 66-69.
Erhart A, Thang ND, Speybroeck N, Tuy TQ, Trung HD, Van Bortel W, Cong LD, Coosemans M, DAlessandro U. Epidemiology of malaria in a rural area of central southern Vietnam: a prospective community based study [abstract]. Acta Trop 2002; 83(Suppl.1): S48, Abstract Nr.MOPS040.
Hutse V, Abdellati S, De Doncker S, Rijal S, Karki BMS, Campinho L, Jacquet D, Boelaert M, Dujardin JC. Development and evaluation of a simple and cheap PCR-ELISA assay for diagnosis of visceral leishmaniasis [abstract]. Acta Trop 2002; 83(Suppl.1): S57, Abstract Nr.TUPS021.
Lejon V. Neuro-inflammation in human West-African trypanosomiasis: a basis for improved stage determination [dissertation]. Antwerpen: Universiteit Antwerpen, Faculteit Wetenschappen, Biochemie; Antwerpen: Prins Leopold Instituut voor Tropische Geneeskunde, Departement Parasitologie, 2002: 209 pp.
Lejon V, Büscher P. Sleeping sickness: from intrathecal IgM synthesis to card agglutination [abstract]. Acta Trop 2002; 83(Suppl.1): S70, Abstract Nr.WEPS005.
Lukuka KA, Kibonge MC, Mumba ND, Lokombe BJ, Muyembe TJJ, Van der Veken W, Büscher P, Vervoort T, Makabouza M, Betukumeso JK, Bilenge MM. Integrated serological screening for human African trypanosomiasis by first line health services in Kinshasa, D. R. Congo [abstract]. In: Integration and disease control; international colloquium, Antwerp, 26-27-28 November 2002; abstract book. Antwerp: Institute of Tropical Medicine, 2002: 57.
Manguin S, Trung HD, Baimai V, Coosemans M. New methods of identification and characterization of malaria vectors for improving vector control in Southeast Asia: two multi-plex PCR for differentiating species within the Anopheles minimus and An. dirus complexes. Mekong Malaria Forum 2002; 10: 148-149.
Mbaye A, Sow S, DAlessandro U, Diop MM, Diop M, Moerman F, Gryseels B. Sudden appearance of haematemesis 10 years after the beginning of a schistosomiasis mansoni epidemic in north Senegal [abstract]. Acta Trop 2002; 83(Suppl.1): S52, Abstract Nr.TUPS008; S99, Abstract Nr.MoWs011.
Mulumba PM, Longo MB, Bobanga LT, Elsen P, Le Ray D, Wéry M, Carlier Y, Kalenga H. La maladie de Chagas: une menace pour lAfrique. Congo Méd 2002; 3: 720-722.
Polman K, De Vlas SJ, Deelder AM, Gryseels B. The relationship between CAA concentrations, egg counts and worm burdens in human Schistosoma mansoni infections is more complex than assumed [abstract]. Acta Trop 2002; 83(Suppl.1): S60, Abstract Nr. TUPS030.
Rijal S, Boelaert M, Karki BMS, Jacquet D, Singh R, Chance ML, Chappuis F, Hommel M, Van der Stuyft P, Le Ray D, Koirala S. Evaluation of a urinary leishmanin antigen based latex agglutination test Katex in the diagnosis of kala-azar in eastern Nepal [abstract]. Acta Trop 2002; 83(Suppl.1): S57, Abstract Nr.TUPS022.
Scott JT, Diakhaté M, Vereecken K, Fall A, Diop M, Ly A, Declercq D, de Vlas SJ, Berkvens D, Kestens L, Gryseels B. Age dependent resistance to Schistosoma mansoni infection; from water contact studies to cytokine-endocrine interactions [abstract]. Acta Trop 2002; 83(Suppl.1): S60, Abstract Nr. TUPS029.
Scott JT, Johnson CR, Guédénon A, Gryseels B, Portaels F. Buruli ulcer strikes independently of age, sex or Schistosoma haematobium infection in Benin [abstract]. Acta Trop 2002; 83(Suppl.1): S75, Abstract Nr. WEPS018.
Sow S, de Vlas SJ, Mbaye A, Polman K, Gryseels B. Low awareness of intestinal schistosomiasis in a rural community in northern Senegal after 7 years of intense health education [abstract]. Acta Trop 2002; 83(Suppl.1): S164, Abstract Nr. P151.
Sow S, de Vlas SJ, Polman K, Mbaye A, Mbow EA, Gryseels B. Monitoring of potential sources of contamination of streams with schistosome eggs in a rural area of northern Senegal: a pilot study [abstract]. Acta Trop 2002; 83(Suppl.1): S99, Abstract Nr. MoWs010.
Talisuna AO, Bakyaita N, Langi P, Mutabingwa T, Watkins W, Van Marck E, Egwang T, DAlessandro U. Role of molecular markers for the community-based surveillance of Plasmodium falciparum-resistant malaria in Ugandan sentinel sites [abstract]. In: The Third MIM Pan-African Malaria Conference, November 17-22, 2002, Arusha, Tanzania. [s.l.]: [s.n.], 2002: Abstract Nr. 120.
Tinto H, DAlessandro U, Guiguemde R. Chloroquine and sulfadoxine-pyrimethamine efficacy for uncomplicated malaria treatment and haematological recovery in children in Bobo-Dioulasso, Burkina Faso, during a 3-year period (1998-2000) [abstract]. In: The Third MIM Pan-African Malaria Conference, November 17-22, 2002, Arusha, Tanzania. [s.l.]: [s.n.], 2002: Abstract Nr. 123.
Van Bortel W. Recognition and characterisation of the members of the Anopheles minimus complex: towards improved malaria vector species identification [dissertation]. Antwerpen: Universiteit Antwerpen, Faculteit Wetenschappen, Departement Biologie; Antwerpen: Instituut voor Tropische Geneeskunde, Departement Parasitologie, 2002: 167 pp
Van Bortel W, Cong LD, Trung HD, Socheat D, Sochanta T, Phompida S, Keokenchan K, DAlessandro U, Erhart A, Coosemans M. Understanding vector and human ecology for improving malaria vector control. Mekong Malaria Forum 2002; 10: 9-11.
Van Bortel W, Coosemans M. The need to develop an efficient network for monitoring insecticide resistance at regional level. Mekong Malaria Forum 2002; 10: 23-24.
Van Bortel W, Trung HD, Thang ND, Roelants P, Erhart A, Coosemans M. Improved malaria vector identification in a rural area of south-central Vietnam: is the right species targeted [abstract]. Acta Trop 2002; 83(Suppl.1): S72, Abstract Nr.WEPS010.
Van der Werf MJ, Bosompem KM, Landouré A, Mbaye A, de Vlas SJ. Quantitative evaluation of schistosomiasis case management in the health systems in Senegal, Ghana and Mali [abstract]. In: Integration and disease control; international colloquium, Antwerp, 26-27-28 November 2002; abstract book. Antwerp: Institute of Tropical Medicine, 2002: 63.
Verdonck K, Alvarez E, Narvarte G, Miranda C, Le Ray D, Gotuzzo E. Differential diagnosis of chronic skin ulcers at the department of infectious diseases in a public hospital in Lima, Peru [abstract]. Acta Trop 2002; 83(Suppl.1): S89, Abstract Nr.WEPS051.
Verloo D, Büscher P. Validation of diagnostic tests for T. evansi in absence of a gold standard [abstract]. In: 23rd Annual Meeting of the OIE, ad hoc Group on NTTAT, 26 May 2002, Paris, France. [s.l.]: [s.n.], 2002.
Verloo D. MCMC techniques in veterinary diagnostic test validation [abstract]. In: Stochastic computation workshop, Durham, North Carolina, 25 September - 3 October 2002. [s.l.]: [s.n.], 2002.