Infectiousness
Next: Human Transmitting Capacity
Malaria transmission is affected by the time course of human infectiousness. For malaria parsites infecting a host, infectiousness starts after mature gametocytes first appear in the blood. The probability of infection is not just about the presence of mature gametocytes, but also at densities high enough to infect a mosquito. For Plasmodium falciparum, parasites are in the liver for the first six days, and it takes 8-10 days for gametocytes to mature, so the earliest a person could possibly infect a mosquito is approximately two weeks after the infective bite. Thereafter, gametocyte densities and infectiousness increase, peaking 3-4 weeks after the bite.
In autonomous systems of equations, like the Ross-Macdonald model, threshold criteria and steady states depend only on the average infectiousness of a human. In models with seasonally forced transmission, the timing matters.