Genetic variability of the human filarial parasite, Wuchereria bancrofti in Southern parts of Nepal

Abstract

Introduction: Lymphatic filariasis (LF) is a neglected tropical disease, caused by Wuchereria bancrofti parasite and pose potential risk to about 1.4 billion people in 73 countries. In Nepal, 60 out of 75 districts are endemic and nearly 90% of the population is at risk and mass drug administration (MDA) has beenin place since 2003. Yet, information about the genetic diversity of W. bancrofti is largely lacking.

Methods: The genetic variability of the parasites in two localities Kailali and Kapilbastu from south- western parts of Nepal were studied. Blood samples were collected at night and stained with Giemsa stain and positive archived slides were taken for the study. W. Bancrofti was individually picked under microscope and gDNA was isolated from the pooled (100 mf) samples. Short Tandem 29bp Repeats (STR) from the intronic region of Abundant Larval Transcript-2 (ALT-2) gene and haplotype mapping of the Internal Transcribed Spacer (ITS-1) region were studied. The phylogenetic trees were constructed and analyzed.

Results: The analyses of STR, haplotypes and the phylogenetic trees indicated the presence of at least two genetically distinct clusters among the W. Bancrofti parasite populations in two areas.

Conclusion: The study identified two genetically distinct clusters of mf in the populations. The finding of two genetic “variants” of W. bancrofti in the present study has important implications for filariasis epidemiology and control/elimination program.