Infectivity of symptomatic and asymptomatic Plasmodium vivax infections to a Southeast Asian vector Anopheles dirus

摘要

Plasmodium vivax is now the predominant species causing malarial infection and disease in most non-African areas, but little is known about its transmission efficiency from human to mosquitoes. Because the majority of Plasmodium infections in endemic areas are low density and asymptomatic, it is important to evaluate how well these infections transmit. Using membrane feeding apparatus, we fed Anopheles dirus with blood samples from 94 individuals who had natural P. vivax infection with parasitemias spanning four orders of magnitude. We found that the mosquito infection rate is positively correlated with blood parasitemia and that infection begins to rise when parasitemia is >10 parasites/μl. Below this threshold, mosquito infection is rare and associated with very few oocysts. These findings provide useful information for assessing the human reservoir of transmission and for establishing diagnostic sensitivity required to identify individuals who are most infective to mosquitoes.