Genetic heterogeneity of Wuchereria bancrofti populations at spatially hierarchical levels in Pondicherry and surrounding areas, south India

Lymphatic filariasis (LF), caused by Wuchereria bancrofti is widely distributed in areas of India with variable geoclimatic factors. These factors, coupled with chemotherapeutic pressure exerted for past half a century may have influenced the genetic structure of the parasite populations. A complex genetic structure of parasite populations will have major consequences to the on-going global LF elimination programme. Hence, it is of interest to understand the genetic heterogeneity of W. bancrofti parasite populations. We studied the genetic heterogeneity of populations of W. bancrofti populations from mf carriers residing in an urban area of Pondicherry and surrounding villages through molecular (RAPD) fingerprinting. The analysis showed that W. bancrofti populations of an urban area were mostly highly heterogeneous, while those of rural areas were homogenous. The urban parasite populations appeared to be a pool of parasite population originating from surrounding rural areas. At least two genotypes, exhibiting high genetic differentiation and minimum gene flow between them, existed in Pondicherry urban areas. There was a minimum gene flow between parasite populations of villages. The genetic heterogeneity of parasite population in an adult microfilariae carrier was significantly high, possibly due to accumulation of different genotypes of the parasite with increasing age. The genetic heterogeneity of W. bancrofti populations in an individual mf carrier, in urban and rural areas, within an endemic area at large, and in different geographical regions of India may have far reaching implications to the epidemiology and strategies of chemotherapy control being adopted for LF elimination programme launched on a global scale.