[BANGKOK] Countries that are already grappling with twin epidemics of tuberculosis (TB) and HIV may have to deal with the additional complication of malaria in areas where the disease is endemic, according to a report presented during the 15th International AIDS Conference held last week in Bangkok, Thailand.
"The biggest challenge of the HIV epidemic is that it is superimposed on pre-existing epidemics of tuberculosis, malaria and sexually transmitted infections (STIs), all fuelled by inadequate health care infrastructures," said Diane Havlir of the University of California in San Francisco. "It is of concern especially when the three infections dominate an area."
Malaria, tuberculosis and HIV/AIDS cause differing patterns of sickness and death, and affect the human immune system in different ways. In practical terms, it means that doctors face additional challenges when treating patients with more than one infection.
Public health initiatives against one or more of the three infections could be used as an entry point for HIV care, said Havlir. She suggested that additional HIV screening points could be introduced in programmes to control TB and treat STIs, and during preventive malaria treatments for pregnant women.
However, Ritu Priya, associate professor at the Centre for Social Medicine and Community Health at the Jawaharlal Nehru University in Delhi, cautions that it is not wise to screen all TB patients for HIV. He thinks it would increase stigmatisation of TB patients, especially in Asian countries.
"Large-scale screening for HIV by itself is meaningless if it does not lead to improved surveillance data or improved access to treatment and care of the infected," says Priya.
Links between HIV and malaria and between HIV and TB are progressively being confirmed. Recently, research conducted in Malawi and reported in The Lancet* showed that HIV impairs immunity to malaria in pregnant women.
Tuberculosis is the most common cause of death in HIV-infected persons and up to 71 per cent of HIV-infected adults in sub-Saharan Africa and 22 per cent in Southeast Asia are estimated to be infected with TB. Researchers have already reported on the rising incidence of TB and HIV in Africa and Asia and on the successful control of TB by treating HIV in people with both infections.
Treatments for malaria and HIV can, however, conflict. In countries where the parasite responsible for malaria is endemic, pregnant women are put on intermittent preventive therapy and babies are sometimes treated as well. HIV-positive pregnant women are also given preventive treatments for HIV, both against opportunistic infections and mother-to-child transmission of the virus.
The guidelines for treatments for the two infections often conflict and could be on a "collision course" said Havlir. There are problems of drug resistance and cross-reactions between drugs, as well as concerns that some medications used to treat HIV-infected persons could be harmful for malaria treatment in certain settings.
Doctors are already encountering cross-reactions between drugs in people infected with TB and HIV. The anti-TB drug rifampicin, for instance, can reduce the effect of a class of HIV drugs called protease inhibitors by up to 92 per cent, according to Papa Salif Sow, from the Department of Infectious Diseases at the Dakar University in Senegal.
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