Epizootiology of the Japanese saurian malaria parasite, Plasmodium sasai.
Histological examination of hearts from 422 Japanese lacertids Takydromus tachydromoides collected at Hanno, Saitama-ken, Honshu, from 1965 to 1967, demonstrated the presence of Plasmodium sasai Telford and Ball, 1969 in 85% of first-year lizards and 92% of those older than 1 yr. Prevalence in 1966-1967, estimated by examination of blood films alone was < 1%, and no infections were detected in 1965 by this method. Prevalence differed only slightly or not at all between years, seasons, host age group, or host sex. Infection occurred immediately after hatching from August into October in each year. In the cohort hatched in 1965, prevalence had reached 100% by November, declined slightly following hibernation, but reached 100% by May. Phanerozoites were present in every month, but encysted chronozoites were found most often in March, following hibernation. Erythroid cells that contained 2->20 uninucleate parasites were sequestered within capillaries of the heart in newly infected juvenile lizards. Vectors apparently were infected from adult lizards with chronic, low level, predominantly gametocytic infections in late summer and fall and transmitted P. sasai to at least 80% of the hatchling cohort, beginning within the first few days of life, producing parasitemias at barely detectable levels. Some transmission may have occurred in late spring but probably to no more than 15% of the host population.
Telford
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SR
Florida Museum of Natural History, University of Florida, Gainesville 32611, USA.
D000367:Age Factors; D000818:Animals; D015331:Cohort Studies; D005260:Female; D006321:Heart / Q000469:parasitology*; D007564:Japan / Q000453:epidemiology; D008116:Lizards / Q000469:parasitology*; D008288:Malaria / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*; D008297:Male; D010961:Plasmodium / Q000302:isolation & purification*; D015995:Prevalence; D012621:Seasons