Histamine is recognised as a key factor in the pathogenesis of allergic diseases but its role in malaria pathogenesis remains unclear. Increased histamine in plasma and tissues is associated with disease severity in human infections with P. falciparum and in animal models of malaria. Plasma histamine concentration was elevated by almost fivefold in a study of children suffering from malaria. Additionally, in this study higher levels of histamine were observed in children with severe malaria as compared to those with lesser disease presentations. Interestingly, a previous study showed that histamine levels were elevated in malaria, but continued to rise during the clinical course of infection only in those who later died. Similarly, a progressive increase in histamine levels during the course of infection was observed in a recent study in mice.
Most work on histamine has been conducted principally on animals with very few on humans. Unfortunately, these human studies were limited in the number of malaria patients examined and patients were not clearly defined clinically. Now that there are better clinical case definitions of malaria, this project will carry out a detailed study of histamine levels in Malawian children with malaria on a larger sample size to have a better understanding of histamine levels in malaria.