The host response in malaria and depression of defence against tuberculosis

Malaria causes significant morbidity and mortality world-wide. Both asympto matic and symptomatic malarial infections cause immune depression, which pr edisposes the host to infection with other microorganisms. Specific clinica l investigations have shown, for example, that those with malaria-attributa ble anaemia are particularly likely to have Salmonella septicaemia, and tha t asymptomatic malarial infection causes diminished response to polysacchar ide vaccine. The results of clinical studies and experiments with animal mo dels have revealed that malarial parasites can decrease their vertebrate ho st's effective humoral and cellular immune responses. In this review, the p ossible ways in which this malaria-induced immune impairment could affect t he host's response to Mycobacterium tuberculosis infection are considered. Could malarial infection be one of the reasons for the persistence of tuber culosis in malaria-endemic regions?