Harbouring in the brain: A focus on immune evasion mechanisms and their deleterious effects in malaria and human African trypanosomiasis

Malaria and human African trypanosomiasis represent the two major tropical vector-transmitted protozoan infections, displaying different prevalence and epidemiological patterns. Death occurs mainly due to neurological complications which are initiated at the blood-brain barrier level. Adapted host-immune responses present differences but also similarities in blood-brain barrier/parasite interactions for these diseases: these are the focus of this review. We describe and compare parasite evasion mechanisms, the initiating mechanisms of central nervous system pathology and major clinical and neuropathological features. Finally, we highlight the common immune mediated mechanisms leading to brain involvement. In both diseases neurological damage is caused mainly by cytokines (interferon-gamma, tumour necrosis factor-alpha and IL-10), nitric oxide and endothelial cell apoptosis. Such a comparative analysis is expected to be useful in the comprehension of disease mechanisms, which may in turn have implications for treatment strategies.