The Joint United Nations Programme on HIV/AIDS (UNAIDS) and the World Health Organization (WHO) have welcomed the consensus reached by experts to recommend the prophylactic use in Africa of cotrimoxazole, a drug that wards off some of the opportunistic infections to which HIV-infected people are prone.

"It was a difficult decision because the research is not definite yet," said Peter Piot, Executive Director of UNAIDS. "But if there is a real chance that using cotrimoxazole can improve the quality of life of millions of HIV-infected Africans, then we have an obligation to treat it seriously."

Widespread prophylactic, or preventive, use of cotrimoxazole in Africa has been delayed by inconsistencies in research results. Two studies in Côte d'Ivoire last year, one by French researchers and the other by US scientists, demonstrated that the drug reduces the frequency of opportunistic illnesses among HIV-infected people. In one of these studies, a reduction in the number of AIDS-related deaths was observed. Preliminary results of two recent UNAIDS-sponsored studies, one from South Africa, and one from Malawi, confirmed that cotrimoxazole is safe in HIV-infected people, and the Malawi study indicated a significant beneficial effect on mortality.

There has also been controversy about whether this drug, widely used in the West, should be used in Africa. In the West, cotrimoxazole is routinely used to prevent pneumocystis carinii pneumonia or PCP, a parasitic type of pneumonia common in industrialized countries among HIV-infected people. Since PCP is not as common in Africa, the use of cotrimoxazole was seen as questionable. Experts have argued with success, however, that PCP is not the only parasitic infection against which cotrimoxazole can work and so have advocated its use.

Common HIV-related infections in sub-Saharan Africa that can be prevented by cotrimoxazole include certain bacterial pneumonias and diarrhoeal diseases as well as certain septicemias. Cotrimoxazole may also protect against toxoplasmosis, a parasitic brain disease, and isosporiasis, a parasitic infection of the intestines.

"Because of the gravity of the HIV epidemic in Africa, this is the best possible decision, based on the limited data that we have," said Dr. Ebrahim Samba, Regional Director for WHO-Africa Region. "We will proceed in a step-wise fashion while evaluating the effectiveness and the impact of this intervention at country level."

The international meeting, held in Harare last week, was a joint UNAIDS-WHO consultation and was attended by scientists, activists, clinicians and heads of national AIDS programmes in Africa. They recommended that cotrimoxazole be used for prophylaxis in adults and children living with HIV or AIDS in Africa as part of a minimum package of care. Criteria for the drug's use were established, covering patient selection, drug regimens, duration of treatment, follow-up, drug supply, education and training, monitoring for drug resistance and adverse effects, evaluation of clinical effectiveness and further research. Guidelines for implementing prophylaxis programmes will be published shortly.

Cotrimoxazole costs between US$ 8 and US$ 17 per person per year for prophylaxis. It is widely available throughout the continent and preliminary analysis has shown that the use of cotrimoxazole prophylaxis is a cost-effective intervention in Africa, particularly if combined with increased access to voluntary counselling and testing for HIV infection.

The other challenge faced in deciding whether to recommend the use of cotrimoxazole in Africa is the risk of creating microbial resistance to the drug if it is widely utilised as a prophylactic. When patients in high-income countries develop infections resistant to a drug, alternatives are often available. This is not as true in Africa, where cotrimoxazole is one of the few affordable and widely available drugs recommended for common infectious illnesses such as pneumonias in children and bacterial diarrhoeas.

The issue of resistance remains important to Africa's use of the drug. Scientists are aware that using cotrimoxazole in Africa is only a medium-term solution. Future research will therefore include investigation into alternative antimicrobial agents.

"It is essential to weigh the question of cotrimoxazole against the two challenges of differing infections and possible resistance," said Dr Piot. "But on a continent where antiretroviral drugs are still beyond the reach of most, it is urgent to help prevent opportunistic infections in people living with HIV/AIDS.

In sub-Saharan Africa, where 23.3 million people live with HIV or AIDS, 13.7 million have already died because of the epidemic. In 1999 alone, there were 3.8 million new infections in the region.