A retrospective examination of mosquito infection on humans infected with Plasmodium falciparum.

A retrospective examination was made of archival data collected between 1940 and 1963 on the infection of mosquitoes with Plasmodium falciparum. Patients were undergoing malariatherapy for the treatment of neurosyphilis. A total of 913 lots of Anopheles quadrimaculatus and An. albimanus were fed on 173 patients. Mosquito infection continued to occur in a few patients beyond 200 days of patent parasitemia. The primary period of mosquito infection occurred during the first 20 days of gametocytemia. Of the 311 lots of mosquitoes fed during this period, 209 (67.20%) were infected, and of these, 163 had greater than 50% of the mosquitoes in the lots infected with at least one oocyst. During secondary periods of gametocytemia, 293 (78.76%) of 372 lots of mosquitoes were infected. The highest percentages of mosquitoes were infected from four days before to four days following peak gametocyte density. Mosquito infection rates were similar to those seen in studies with splenectomized Aotus monkeys experimentally infected with P. falciparum.