Bancroftian filariasis in Pondicherry, south India: 1. Pre-control epidemiological observations

A 5-year Integrated Vector Management (IVM) project was implemented in Pondicherry, South India, for the control of Bancroftian filariasis. The efficacy of the IVM strategy was compared with routine control strategy under the national programme. The present paper describes the pre-control epidemiological features of filariasis as determined by a mass blood survey in 1981. Of 24946 persons examined 8.41% were microfilaraemic. Microfilaraemia prevalence was homogeneous throughout the study area. The prevalence and intensity of microfilaraemia were age dependent, and increased monotonically until about 20 years, following which there was a decline until about 40 years to become relatively stable in older age classes. The gender profiles of both prevalence and intensity of microfilaraemia showed no difference between the sexes until about 15 years of age, following which both were higher in males compared to females. The distribution of microfilarial counts was overdispersed, indicating aggregation of adult worms.