SummaryWe conducted a 2-year (1997)(1998)(1999) longitudinal, entomological and virological study in three dengue endemic villages in Vellore district, Tamil Nadu, to understand the dynamics of dengue transmission. Aedes aegypti (Linn.), Ae. albopictus (Skuse) and Ae. vittatus (Bigot) were the prevalent vector species. Aedes aegypti was breeding throughout the year with a Breteau index ranging from 9.05 to 45.49. Aedes albopictus and Ae. vittatus were prevalent mainly in the rainy season. Small water holding containers (cemented tanks/cisterns) were the perennial breeding source of Ae. aegypti, and its abundance was significantly higher in semi-urbanized central areas than the peripheral areas of the villages. From 271 pools (4016 specimens) of adult females, eight dengue virus (DENV) isolates were obtained of which seven were from Ae. aegypti and one from Ae. albopictus. This is the first report of DENV isolation from Ae. albopictus in rural India. Infection rates in the two species were comparable. However, due to higher and perennial prevalence, Ae. aegypti is considered as primary vector with Ae. albopictus playing a secondary role. Despite circulation of all four serotypes (DENV 1-4) detected mainly during the transmission season, the high anthropophilic index of the vectors and their abundance, no human dengue case was reported, suggesting silent dengue transmission.

SummarySeven village units endemic for ®lariasis were assigned randomly into three arms with different intervention strategies in the years 1995 and 1996. Villages in Group A received two annual mass drug administrations (MDAs) of diethylcarbamazine (DEC) plus ivermectin (IVR

SummaryThe efficacy of single-dose combination drug therapy with diethylcarbamazine (DEC) plus albendazole (ALB), and single-drug therapy with DEC alone against geohelminths was compared as part of a mass drug administration (MDA) for elimination of filariasis. This study was conducted in two blocks of Villupuram District of Tamil Nadu State, India, covering a population of 321 000 including about 100 000 children 1-15 years of age. Prevalence and intensity of geohelminth infection were determined by the Kato-Katz technique immediately before and 3 weeks after the MDA. A pre-treatment cross-sectional survey was undertaken in 18 statistically selected villages out of 204 villages, including 646 school children. About 60% were infected with one or more geohelminths. The overall prevalence rates were 53.9%, 12.4% and 5.7% for Ascaris lumbricoides, hookworms and Trichuris trichiura, respectively. Combination therapy (DEC + ALB) produced a cure rate of 74.3% and an egg reduction rate of 97.3% for geohelminths, which were higher than the corresponding rates (30.4% and 79.0%) observed in the single drug therapy arm with DEC alone. The odds of cure with combination therapy were significantly higher for roundworm (5.3 times) and hookworms (3.5 times), then odds of cure with DEC alone. Both therapies were equally effective against trichuriasis, recording cure rates >77% and egg reduction rates >83%. In combination therapy, 53.5% of the children noticed expulsion of worms after MDA, while in single drug therapy only 20.9% did. Our study indicated that MDA of combination therapy was operationally feasible at the community level, and it may secure higher community compliance because of its perceived benefits and enhanced efficacy against geohelminths than single-drug therapy.