WHY SO FEW TRANSMISSION STAGES - REPRODUCTIVE RESTRAINT BY MALARIA PARASITES

Vast numbers of malaria parasites exist in a population: perhaps 10(10 ) in just one vertebrate host. Yet gametocytes, the only stage capable of transmission, usually constitute just a few percent or even less o f the circulating parasites. Why? Parasite fitness should be intimatel y linked with transmission probability and infectiousness rises with g ametocyte density. Here, Louise Taylor and Andrew Read propose several testable hypotheses that might explain why natural selection has nor favoured variants producing more transmission stages.