Interaction between malaria parasite and the host immune system

Edward Lungu
Department of Mathematics, University of Botswana

(May 15, 2013 3:00 PM - 3:50 PM)

Interaction between malaria parasite and the host immune system

Abstract

The malaria parasite life cycle involves three cycles the sporogony (mosquito stage), exo-erythrocytic schizogony (liver stage), and the erythrocytic schizogony (human blood stage). We consider a simpli?ed mathematical model for malaria involving two parasite life cycles within the host namely the exo-erythrocytic and erythrocytic cycles. This study has revealed parasite replication characteristics which offer insights into the processes that allow the parasite to evade the human response during the red blood stages. First, the infection of the red blood cells by extracellular parasites during the erythrocytic cycle is characterized a reproduction number, R 0p ; that is less than one. Secondly, the asexual repro- duction of parasite during the red blood stage characterized by a reproduction number, R0m > 1; is responsible for the pathology of clinical malaria. Thirdly, we have found that the parasite depends mainly on the death of infected red blood cells to rapidly increase its population. Specifcally, the number of parasites, n1; in an infected red blood cell that dies need not be high for the parasite population to grow rapidly. We have found that for 8 ≤ n1 < 16; R0 > 1 and the parasite establishes itself while for 16 ≤ n1≤ 32; R0 < 1 and the parasite fails to establish itself. We are led to conclude that the parasite has preference for infecting older red blood cells as a strategy for evading the immune system.