A baseline survey of filariasis was conducted in two endemic villages in Chingleput
district of Tamil Nadu, to obtain the prevalence rate of microfilaraemia and
that of clinical filarial disease along with its various clinical patterns. Of the 2921
dejure population registered, in 2735 a comprehensive clinical examination for filariasis
was carried out by a physician. In 2658 persons of those clinically examined,
night blood samples were collected by finger prick. The results of the survey confirmed
that the two village were highly endemic for filariasis, the prevalence rates
of clinical disease and microfilaraemia being 20 and 12 per cent respectively. The
endemicity rate was 31 per cent. Nocturnally periodic Wuchereria bancrofti was
the only species identified. The major manifestations of clinical disease were lymphadenitis
in the acute phase, hydrocele and oedema of the lower limbs in the chronic
phase and involvement of the lower limbs in the elephantiasis phase. Among males
with disease in the chronic phase, genital involvement was more than that of the
lower limbs. The distributions of the patients by age in the three phases, although
overlapping, suggested that the disease generally progressed with age from acute
to chronic to elephantiasis phase. The microfilarial rate among persons with clinical
disease was lower as compared to that among persons without disease. An entomological
survey of one of the villages showed that Culex quinquefasciatus was the
vector with high infection and infectivity rates