Malaria transmission at a new irrigation project in Sri Lanka: the emergence of Anopheles annularis as a major vector.
Malaria transmission was studied in a newly irrigated area of the Mahaweli project in the dry zone of Sri Lanka. Observations were performed for a three-month period following the northeast monsoon. Parasitemia in the population varied from 20.2% in February to 7% in May, and infection was due to both Plasmodium falciparum and P. vivax. Night catches of mosquitoes collected with human bait included a high proportion of Anopheles annularis. Mosquitoes containing sporozoites in the salivary glands were identified by an enzyme-linked immunosorbent assay. Anopheles culicifacies, An. annularis, and An. aconitus were all implicated as vectors in the area. The highest entomologic inoculation rate, 0.12 infected bites/hr, was observed with An. annularis and P. vivax in March. We suggest that a change in the ecosystem from dry zone forest to irrigated cultivated land is the cause of the increased prevalence of An. annularis in this area and its emergence as a major vector of malaria.
Ramasamy
R
R
Malaria Laboratory, Institute of Fundamental Studies, Kandy, Sri Lanka.
De Alwis
R
R
Wijesundere
A
A
Ramasamy
M S
MS
D000293:Adolescent; D000328:Adult; D000818:Animals; D000852:Anopheles / Q000469:parasitology*; D002648:Child; D005260:Female; D006801:Humans; D007303:Insect Vectors / Q000469:parasitology*; D008288:Malaria / Q000453:epidemiology / Q000635:transmission*; D008297:Male; D015995:Prevalence; D013188:Sri Lanka / Q000453:epidemiology; D014881:Water Supply