Estimating sporozoite rates by examining pooled samples of mosquitoes.

Pooling sampled mosquitoes for sporozoite detection by immunoassays is an efficient and economic approach in situations of very low vector infectivity. In the present study a strategy was proposed to estimate sporozoite rates using this approach. For this purpose there should be only one infected mosquito in any positive pool, so that the number of positive pools examined is an approximation of the number of infected mosquitoes in sample collections. The rationale underlying the strategy is to specify the maximal pool sizes for the given sporozoite rates so that it is reasonable to assert there is no more than one infected mosquito in any positive pool. A statistical model was developed to calculate the maximal pool sizes for various guessed sporozoite rates. The results showed that maximal pool size declined non-linearly with increases in the given sporozoite rates. With a guessed sporozoite rate < 1% as many as 35 mosquitoes could be pooled for sporozoite determination.