Malaria is one of the most prevalent infectious diseases in the world and it has an estimated mortality of over a million people each year. Approximately 90 % of the annual 300 million cases of acute malaria take place in sub-Saharan Africa, the region with the greatest burden of HIV, with an estimated 30 million people infected over the past two decades. The potential for interactions between the two infections is clearly of considerable public health importance and is also highly relevant in Southeast Asia, as the HIV epidemic continues to grow in regions of high malaria endemicity.
Initial reports suggested that there was little evidence for significant interactions between HIV infection and malaria, but several studies from the last decade have changed this view. These studies demonstrate that the two infections interact with each other in a way that leads to progression of both diseases. HIV-infected people are more likely to experience both malaria parasitaemia and clinical malaria, and acute malaria can up-regulate HIV replication, leading to progression of the HIV infection.
The interactions are most serious in pregnant women, where HIV infection increases the risk of placental malaria, leading to increased infant mortality and increased HIV transmission from mother to child. Women with more than two pregnancies normally achieve a pregnancy specific immunity against malaria, but HIV-infected multigravidae women lack this immunity. Dual infection with HIV and malaria increases the risk of anemia during pregnancy, contributing to an increased risk of HIV transmission from mother to child.
On the other hand, antimalarial therapy can slow down the progression of an HIV infection by reducing the HIV replication. In this way, one may decrease HIV progression and the risk of transmission. In the same way, prevention and treatment of malaria during pregnancy may decrease transmission of HIV from mother to child.
Although initial reports suggested little evidence for significant interactions between HIV infection and malaria, more recent studies have changed this view. This may be of importance for the population in areas with a great burden of both HIV infection and malaria, dominantly in sub-Saharan Africa. However, the studies conducted until now do not show any significant impact on morbidity and mortality in the relevant regions. This means that the interactions between HIV infection and malaria are not yet shown to have serious consequences for public health.