Studies on Sporozoite-Induced Infections of Rodent Malaria

Abstract

Summary Anopheles stephensi was experimentally infected with two strains of Plasmodium berghei. A 58-percent midgut oocyst index and a 43-percent salivary gland sporozoite index were obtained in six feeding experiments in which the mosquitoes were kept at 21°C during the sporogonic development. Very heavy salivary gland invasion was observed in 95 percent of all infected A. stephensi. The number of sporozoites in the glands of A. stephensi averaged 7200 per mosquito. This number was found to be comparable to salivary gland infections in naturally and experimentally infected A. dureni, the natural vector of P. berghei. Though infection rates in A. quadrimaculatus exposed to the same experimental conditions were similar, the number of sporozoites in the salivary glands of this species was considerably smaller (averaging 100–300 per gland) in 92 percent of the infected mosquitoes. The temperature factor as a decisive element in enhancing or retarding sporogonic development of P. berghei is discussed in the light of the experimental results.