[Research on the factors influencing the sporogonic multiplication of Plasmodium vivax in the mosquito vector].

Volunteers with no previous malaria history infected with northern Guangdong isolate of Plasmodium vivax and mosquito vector, Anopheles stephensi, were the objects and materials used in the research. Totally there were 16 volunteers, half of them were infected by mosquito-bite and another half by blood-inoculation. Blood was drawn when parasitemia reached a certain level and the erythrocytic forms developed into large trophozoites. Mosquitoes fed on infected blood from 5 and 4 donors of the two groups gave high gland infection rate and high gland indices respectively, but the highest gland indices were got from volunteers infected by mosquito-bite. The time of blood-feeding is important, only those blood samples taken from the people 3 to 8 days after the first onset gave good sporozoite harvest and the gland infection was greatly reduced on the 9th day. During this period (d3-8), the density of gametocyte had obvious influence on the intensity of mosquito infection. When the sex ratio of gametocyte (female:male) was 4:1 or less, the result would be good. For the purpose of reflecting more perfectly the circumstance of the sporogonic multiplication of plasmodium in the mosquito vector, we suggest the concept of gut/gland infection intensity which equals the product of the infection rate and the index of oocyst/positive gland.