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A final solution is expected from an AIDS vaccine. A number of theoretical approaches are being tested. On the one hand attempts are being made to find a vaccine that prevents infection itself, while on the other hand a vaccine that is administered to persons who are already infected and that influences the course of the infection in the good sense would be very useful. As AIDS vaccines are at present still in an experimental stage, prevention and control of the infection should be concentrated on three levels: sexual transmission, prevention of transmission via contaminated blood or needles, and mother-to-child transmission.
Information for the general population and for particular risk groups, counselling of seropositive persons, condom distribution (prostitutes), promotion of use and availability of condoms, counselling prostitutes, detection and treatment of other sexually transmitted diseases (STDs). In a number of countries it is the custom that after the death of the husband, the wife marries a brother or another member of the deceased’s family. This of course promotes transmission. In many countries the condom is still a very sensitive topic (taboo in public debates or even in private conversations within couples or family). One of the first actions to be taken in the campaign against AIDS in Thailand was the demystifying of the condom by all kinds of educational and promotional campaigns. In contrast to what is sometimes said, the promotion of condom use in tropical countries is not a hopeless task. It is being investigated whether a virocidal cream applied to the vagina offers some protection (so that women no longer have to depend on the good-will of their male partners). Circumcision of the man brings about a 2.5-fold decrease in the risk of HIV transmission from woman to man. It must be emphasised that circumcision does not give absolute protection.
Screening of blood for transfusion, limitation of blood transfusions and injections, strict sterilization of needles, syringes, etc. The intravenous drug abuse problem does not have the same proportions in Africa as it does in developed countries, though it is quite substantial in Southeast Asia. Medical personnel should avoid accidental contact with blood by wearing gloves, by not recapping needles, by putting needles immediately after use into containers with large openings, and by wearing protective clothing, masks, gloves and glasses when assisting childbirth. Hands should be washed with soap and water after contact with body fluids. Correct techniques should (of course!) be used in surgical operations. For example, during a surgical operation the handing over of a sharp instrument such as a scalpel should take place not from hand to hand, but the instrument should first be laid down, after which the next person picks it up. Making sterile needles and syringes available to drug users, as well as methadone projects, have proved useful.
Not all children born to seropositive mothers will be infected. Why some children are infected and others are not is a topic of intensive research. Seropositive women are advised to avoid conception. However, there are many women or married couples who do want a child to symbolically overcome death via their progeny. Breast-feeding should be discouraged if there is an alternative, though the latter is often not the case. Perinatal administration of Retrovir® definitely lowers the risk of transmission. In an American-European study in which Retrovir® was given IV to the mother throughout the third trimester of pregnancy and during childbirth and to the child for 4 weeks a decrease in transmission from 22% to 8% was observed. Shorter schemes with Retrovir® are also effective. Retrovir® appears to be tolerated very well by babies, with only minimal side-effects. In Third World countries Retrovir® will often be beyond the scope of many patients. Perinatal transmission can be reduced by 50% by a single administration of 200 mg nevirapine (Viramune®) to the mother during childbirth and by one dose (2 mg/kg) to the baby within the first 3 days of life. This should be a cheap strategy in Third World countries for reducing intra-partum transmission and transfer via the early maternal milk. Elective Caesarean section carries a significantly lower risk of transmission (about 10%). The advantage of a Caesarean section diminishes when the amniochorionic membranes are broken and/or the mother is already in labour. Combining prophylactic Retrovir® with elective Caesarean section can reduce the risk of vertical transmission to about 2%. The possible place of HAART in this setting is still not clear. Episiotomy, internal monitoring (in any case a luxury), forceps and vacuum extraction are best avoided in vaginal childbirth. After birth, the child should be gently aspirated, the eyes and nose flushed and given a quick bath to remove all blood. Optimal nutrition with enough vitamin A before giving birth is advised (the possibly inhibitory effect of certain retinoids on HIV is being investigated).
While practising their profession, medical personnel run a real risk of accidental infection. The transmission risk from a small accidental needle stick injury is approximately 0.3%. However, the risks vary greatly according to circumstances. The risk increases considerably when large quantities of blood are inoculated or in case of a deep insertion injury. If the blood in a needle stick accident originated from a person with high viral load (in seroconversion, or if viraemia is known through monitoring or in someone with terminal AIDS), the risk is considerably higher than 1/300, increasing to 1/50 to 1/25 or even higher. After exposure through mucosa (getting a blood splash in the eye) the risk is somewhat lower. Post-exposure prophylaxis (so-called PEP) with HAART is now advised or must at least be discussed with the victim. If the risk of infection is found to be unacceptable, treatment should be started quickly (preferably within three hours, maximum delay 72 hours) with the combination Combivir®, 2 x 1 per day together with Crixivan®, Stocrin® or Viramune® (starting with 200 mg nevirapine) for 4 weeks. The combination Combivir® with Kaletra® is an alternative. If there is a high viraemia in the source patient while the latter is taking virostatic drugs and resistance can thus be expected, it is best to use a cocktail different from that used by the patient.
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Post-exposure prophylaxis: summary
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Priorities in combatting AIDS:
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Experimental
A number of vaccines are now being tested in clinical trials. The search for an efficient AIDS-vaccine is a frustrating enterprise. One approach was to use a genetically engineered version of HIV's surface protein GP120. In 2003, the results of the first full-scale efficacy test (a 5000-person, 3-year trial by Vaxgen of California) were made public. The vaccine plainly failed. Nevertheless, hope has not been given up. A Canarypox/HIV vaccine is being planned.
