Research Article

Plasmodium vivax: gametocyte infectivity of naturally infected Thai adults

Jetsumon Sattabongkota1, Nongnuj Maneechaia1 and Ronald Rosenberga1

a1 Department of Entomology, US Army Medical Component, 315/6 Rajavithi Road, Bangkok 10400, Thailand


Up to 200 laboratory reared Anopheles dirus mosquitoes were fed on each of 496 symptomatic Thai men who had patent, naturally acquired Plasmodium vivax gametocytaemia. Mean gametocyte densities were 455/mm3 (range: 0–3281), geometric mean oocyst number was 9 (0–142), mean frequency of infection was 43% (0–100%), and mean sporozoite number in salivary glands was 9525 (0–285 000). There was little relation between gametocyte density and either oocyst number or frequency of mosquito infection. There were, however, statistically strong positive correlations between oocyst numbers and frequency of infection, and between number of oocysts and number of salivary gland sporozoites. The data suggest that each oocyst contributed about 850 sporozoites to a gland infection.

(Received June 21 1990)

(Revised September 03 1990)

(Accepted September 11 1990)