1 Eosinophilia with abdominal symptoms
- 1.1 General
- 1.2 Diagnosis
2 Eosinophilia with pruritus
3 Eosinophilia with respiratory symptoms

POST-TRAVEL: EOSINOPHILIA

1 Eosinophilia with abdominal symptoms

1.1 General

Occurrence of abdominal complaints together with peripheral hypereosinophilia with or without increased IgE values and/or Charcot-Leydig crystals in the faeces is a frequent problem after travel in the (sub)tropics. A problem that occurs during or after a trip does not necessarily need to have a causal connection with that trip. It may be an incidental combination of eosinophilia and abdominal discomfort (no causal relationship). It occasionally is a cosmopolitan condition, though there is often an exotic cause.

Worm infestations are often responable for eosinophilia and abdominal complains. As a rule it can be stated that protozoa do not cause eosinophilia, with the exception of Sarcocystis (eosinophilic enteritis) and Isospora belli, although this is controversial.

1.2 Diagnosis

An attempt should be made to identify the parasite. This can sometimes be done via simple examination of the faeces. Concentration methods may be necessary, particularly with species that produce few eggs or larvae. X-rays, ultrasound, endoscopy and biopsies may have to be called upon for other parasites. Diagnosis can sometimes be made only on a surgical excision biopsy.

1.2.1 Faecal examination

Ascaris lumbricoides can usually be detected easily by simple faecal examination. It should be pointed out that eosinophilia will occur principally during the parasite’s migration phase. Once the worm has grown into the adult animal in the lumen of the intestine the eosinophilia usually diminishes or returns to normal.

Hookworms or ancylostomiasis can usually be found in the faeces without problems. If the ova have all eclosed it should be possible to differentiate the larvae from those of Strongyloides stercoralis. Oesophagostomum larvae resemble hookworm larvae.

Schistosomiasis due to both Schistosoma mansoni and S. japonicum and to a lesser extent to S. intercalatum and S. mekongi is a major cause of eosinophilia and abdominal discomfort. One must not forget the acute Katayama syndrome, where initially no ova are found in the faeces.

Strongyloides stercoralis larvae are often difficult to detect with a standard coprological examination, and therefore a Baerman concentration test can be indicated.

It is most important to detect Capillaria philippinenesis as this parasite can have a fatal outcome. Severe abdominal pain, diarrhoea, emaciation and eosinophilia are the most obvious symptoms.

Infestations by liver flukes such as Fasciola hepatica cause abdominal discomfort. After the parasite’s migration phase this is restricted to the liver.

Infestations with intestinal flukes such as Heterophyes heterophyes, Metagonimus yokogawai, Gastrodiscoides hominis, Echinostoma sp, Euparyphium sp. and Fasciolopsis buski are usually asymptomatic, unless they are present in massive numbers. Metorchis conjunctus is a North American liver fluke that can cause acute abdominal pain and eosinophilia (e.g. after the human host has eaten raw fish).

In rare cases it is adult tapeworms (Taenia sp., Diphyllobothrium latum, Hymenolepis sp., Dipylidium caninum, Inermicapsifer, Bertiella sp., Raillietina sp, Diplogonoporus sp.) which are responsible for abdominal discomfort.

1.2.2 Serology

Cross-reactivity is a problem with a number of serological tests for detection of worm infections. Serological testing can lead to suspicion of a visceral migrating larva (toxocariasis). Confirmatory diagnosis can only be made via biopsy. Detecting seroconversion is very important in Katayama syndrome. Initially negative while the patient has fever or thoracic and abdominal discomfort, this will later become positive. Ova of the schistosomes can subsequently be demonstrated in a rectum biopsy or urine sample (e.g. after swimming in Lake Malawi or in visitors of the Dogon plateau).

1.2.3 X-rays

Pentastomiasis (Armillifer armillatus infestation) is a rare cause of abdominal discomfort. Some time afterwards the calcified, comma-shaped larvae can be observed on an X-ray of the abdomen. If there is an infestation with exclusively male Ascaris lumbricoides, there will be no eggs in the stools, but the adult parasite can be detected via X-rays of the small intestine (barium transit). Calcified Echinococcus lesions are likewise detectable by X-ray.

1.2.4 Ultrasound

Liver flukes in the bile ducts or an aberrant migration of an adult Ascaris (Wirsung duct, choledocus) can be detected by ultrasound. An ultrasound of the abdomen can show dilated bile ducts. Liver lesions due to Capillaria hepatica are found only very rarely. No ova of this latter parasite appear in the faeces. Echinococcosis also tends to affects the liver. Fibrosis of the liver due to schistosomiasis can be suspected on ultrasound (periportal fibrosis).

1.2.5 Endoscopy

Anisakis worms (anisakiasis) can be diagnosed via gastroscopy and treated by mechanical extraction of the worm.

1.2.6 Biopsy and surgery

Rectum biopsy is a sensitive technique for detection of dead or living Schistosoma ova. Oesophagostoma worms can be found via surgery in intestinal abscesses. A few other rare parasites can also produce eosinophilic intestinal abscesses, namely: Angiostrongylus costaricensis, anisakiasis due to Anisakis simplex, Pseudoterranova decipiens, Phocanema, Contracaecum or Hysterothylacium. Eustrongylides sp. are large, bright red nematodes that elicit severe intestinal lesions. Macracanthorhynchus hirudinaceus is a thornhead worm or acanthocephalus that fortunately only seldom infects humans.

2 Eosinophilia with pruritus

2.1 General

There is sometimes an incidental combination of eosinophilia and pruritus (no causal relation). In a traveller to the (sub)tropics, it occasionally concerns a cosmopolitan disease, though there is often an exotic cause. Scabies (Sarcoptes sp.) and pubic lice (Phthirus pubis) are a frequent cause of pruritus, but do not so frequently cause eosinophilia.

2.2 Reactions to bites and stings

Reactions to insect bites and stings (Culicoides sp, bedbugs, etc.), trombiculosis (harvest mites), contact dermatitis (e.g. to plants) and allergic reactions to medications taken during a trip sometimes raise diagnostic problems. Itching dermatitis can be elicited by the hairs of caterpillars of certain Lepidoptera. The hairs of certain bird spiders can also cause prolonged, severe pruritus.

2.3 Worm infestations

Worm infestations must be considered. Certain infections are obvious at a glance (e.g. typical larva currens, larva cutanea migrans). Other diseases are much more difficult to identify (e.g. gnathostomiasis). It should be borne in mind that a positive parasitological result may confirm the diagnosis, but that a negative result is less conclusive. In filarioses one is often confronted with the difficulty of amicrofilaraemic infections. This latter problem frequently occurs with Loa loa infections. Calabar swellings and subconjunctival migration of the adult worm will suggest the diagnosis in these cases. Note that Onchocerca volvulus microfilariae are only found in dermal fluid (not in blood). Serological tests have only a limited sensitivity and specificity. Ectopic localisations of worms can cause various cutaneous symptoms (e.g. Poikilorchis infestations, sparganosis). Cercarial dermatitis can occur after skin contact with contaminated fresh water. Early after infestation no Schistosoma ova will yet be detectable. If the infection is casued by a parasite species which has an animal (e.g. birds) as its normal host, the cercarial dermatitis will be more pronounced, but no patent infection will ensue. One of the frequent causes of urticaria in travellers is anisakiasis. This condition is frequently misdiagnosed as allergy to fish.

2.4 Itching after swimming in seawater

A planula larva dermatitis will occur shortly after bathing in seawater in which these microscopic animals (coelenterata) are present in large numbers. Fire coral dermatitis can cause quite annoying discomfort (irritation due to nematocysts). Contact with jellyfish can cause linear skin lesions. Traditional aquagenic urticaria is not related to travel.

3 Eosinophilia with respiratory symptoms

There may be an incidental combination of eosinophilia and respiratory symptoms (no causal relationship). A cosmopolitan disease (e.g. asthma) may occasionally be involved, but there is often an exotic cause in travellers with recent onset respiratory problems and eosinophilia.

Among the exotic causes we mention paragonomiasis (lung flukes), Katayama syndrome (acute schistosomiasis) and occult filariosis (Weingarten syndrome or tropical pulmonary eosinophilia syndrome). Migration of various nematode larvae (Ancylostoma, Strongyloides, Ascaris, Toxocara) through the lung can result in Loeffler's syndrome. Strongyloides infections tend to be very persistent (beware of steroids and HTLV-1 infections). Chronic schistosomiasis can also cause pulmonary lesions and eosinophilia. Pulmonary echinococcosis tends to be asymptomatic although narrowing of a bronchial lumen can occur due to external compression.

Asthma can be triggered by hypersensitivity to cockroaches (Blatta sp, Blatella sp, Periplaneta sp) and other insects. Inhalation of urticarial (stinging) hairs of certain caterpillars can provoke acute airway symptoms.