Sporozoite load of mosquitoes infected with Plasmodium falciparum

In the laboratory, mosquitoes given a second blood meal 5-11 d after an infective one have more sporozoites in their salivary glands than do those given a single infective blood meal only. The presence of specific anti-sporozoite antibody in the second blood meal does not reduce the number of sporozoites in salivary glands. On the contrary, the presence of the raised immunoglobulin levels--even non-specific ones--may result in higher gland infections. Oocyst maturation is extremely asynchronous in mosquitoes given a single blood meal, the maturation time being 10-22 d or more. The explanation for the increased density of sporozoites in salivary glands in mosquitoes having a second blood meal may be acceleration of oocyst maturation. Multiple blood meals are a normal event for infectious mosquitoes in nature, and therefore have no special epidemiological significance. However, in the laboratory a second blood meal could be a simple procedure for increasing the efficiency of sporozoite production.