The impact of variations in temperature on early Plasmodium falciparum development in Anopheles stephensi

The effect of temperature on early Plasmodium falciparum development was examined in Anopheles stephensi. The rates of both ookinete development and bloodmeal digestion were lengthened as temperatures decreased from 27 to 21 degrees C. However, low temperatures (21-27 degrees C) did not significantly influence infection rates or densities of either ookinetes or oocytes. In contrast, high temperatures (30 and 32 degrees C) significantly impacted parasite densities and infection rates by interfering with developmental processes occurring between parasite fertilization and ookinete formation, especially during zygote and early ookinete maturation. This study demonstrates clearly that temperature affects the sporogonic development of P. falciparum in anophelines by altering the kinetics of ookinete maturation. These studies not only confirm the ookinete as the key development stage affecting the probability of vector infectivity, they provide new insights into the epidemiology of P. falciparum infections.