Malaria was more frequent in people with HIV in Malawi and a first episode more likely to occur in HIV-positive people with low CD4 cell counts or high viral load, according to findings from a study published in the September 15th edition of the Journal of Infectious Diseases. Malaria prophylaxis for people with HIV should be considered as a routine intervention, the authors suggest, in order to reduce the malaria burden in countries where both HIV and malaria are common.
The study was conducted on a tea estate in Thyolo, Malawi, from October 2000 until June 2001. The malaria season in Malawi runs from late December until late June, which roughly coincides with the rainy season.
The study recruited adults without clinical AIDS or tuberculosis (TB), and matched HIV-positive individuals by location with HIV-negative individuals nearby. All participants were aparasitaemic at enrolment and after ten days follow-up, and at least one further follow-up was available for all participants.
The study recruited 349 individuals who were aparasitaemic at baseline (64% HIV-positive). The median viral load among HIV-positive patients was 85,422 copies/ml and the median CD4 count 337 cells/mm3.
HIV-positive individuals were approximately twice as likely to experience a first episode of parasitaemia during the follow-up period and were two and half times more likely to experience a second episode of parasitemia. The risk of symptomatic malaria was slightly higher (hazard ratio 2.7).
People with higher viral load or a lower CD4 cell count were at higher risk of infection. The risk of parasitemia increased by 20% for every 1 log increase in viral load, meaning that people with a high viral load (above 100,000 copies/ml) were 20% more likely to have parasitemia than people with low viral load (below 10,000 copies/ml). This association was even stronger for second episodes of parasitaemia. However, viral load did no affect the incidence of symptomatic malaria.
Those with CD4 cell counts below 200 were twice as likely to have a first episode of parasitaemia as people with CD4 cell counts above 400 cells/mm3 but CD4 cell count did not affect the risk of a second episode. Individuals with CD4 cell counts below 200 cells/mm3 were 2.3 times more likely to develop symptomatic malaria than those with CD4 counts above 400 cells/mm3.
“The evidence for higher rates of parasitaemia and a first episode of malaria is strong and consistent in adults with HIV,” the authors comment. “This justifies the need for intensified malaria prevention strategies in regions where coinfection with malaria and HIV is common.”
They recommend the consideration of malaria prophylaxis in HIV-positive people, together with antiretroviral therapy if parasitemia is present.
Patnaik P et al. Effects of HIV-1 serostatus, HIV-1 RNA concentration, and CD4 cell count on the incidence of malaria infection in a cohort of adults in rural Malawi. J Infect Dis 192: 984-991, 2005.