Natural history, trend of prevalence and spectrum of manifestations of Bancroftian filarial disease in Pondicherry (South India)

The study examines the changes in the disease parameters of lymphatic filariasis over a period of time based on three surveys during 1957, 1986 and 1992 in Pondicherry, South India. The overall prevalence of filarial disease in the three surveys was 4.7, 6.7 and 9.9% respectively. It was significantly higher in males (1957:5.3%; 1986:13.7%; 1992:18.8%) when compared to females (1957:3.8%; 1986:2.3%; 1992:2.7%) in all the three surveys (P<0.05). The overall prevalence of acute adenolymphangitis declined from 1.0 in 1957 to 0.2 in 1986 and 0.04% in 1992. While the prevalence of hydrocele showed an increasing trend from 2.7 in 1957 to 11.9 in 1986 and 17.3% in 1992, the prevalence of lymphoedema (1.9 in 1957; 1.9 in 1986 and 1.8% in 1992) was stable over the same period. The prevalence of disease was relatively higher in all age groups of both male and female population in 1992 when compared either to 1957 or 1986. Similarly a monotonic increase in the prevalence of hydrocele was observed in all age groups in 1992 when compared to previous surveys. The implications of the changes in prevalence of the chronic manifestations when compared to the changes in the acute manifestations over a period of 35 years are discussed.