AN EPIDEMIOLOGICAL STUDY OF BOVINE FASCIOLOSIS IN POTOHAR REGION, PAKISTAN

Abstract

This study was conducted during 2007-2010 on the Fasciola species isolated from bovines grazing in the Potohar (Punjab) region of Pakistan. The objective of the study was to generate information and baseline data on the identification of Fasciola species with the help of morphometry and genomics. The Phenotypic analysis comprised on the study of morphological parameters and molecular characterization was based on genetic markers (r DNA ITS-1 and ITS- 2), simultaneously genetic diversity was investigated by using microsatellite markers. The prevalence of fasciolosis was also established in the Potohar area by screening grazing cattle and buffaloes. This was achieved by analyzing and comparing fecal egg count and serology. Immunodiagnosis was done by an indirect ELISA test, which was developed to diagnose fasciolosis in this region. The antigen used was ES antigen isolated from the liver flukes present in bovines of Potohar. The species of Fasciola identified in this area was an intermediate, resembling F.gigantica and there is no commercially available ELISA kit to detect infection between F.gigantica and Fasciola spp / F. intermedia. Since the prevalence of fasciolosis is dependent on its intermediate fresh water snail host, the occurrence of snails in selected water bodies of Potohar area was also observed including their infective stages; cercariae along with metacercariae. The monthly cercarial prevalence isolated from two selected snail species was taken into account along with prevalence of aquatic vegetation in the marked water bodies. The snails were observed for monthly cercarial activity, whereas the aquatic vegetation was observed for the presence of metacercariae. xxiiiThe results of the present study report that the species of Fasciola in the Potohar area is an intermediate resembling F.gigantica more than F.hepatica. The microsatellite markers used, show polymorphism and the presence of genetic diversity in Fasciola. Prevalence of fasciolosis was fifty five percent in the bovines grazing in this area. This was seen to be breed, age and sex related and more prevalent in buffaloes as compared to cattle. The snail species prevalent in the marked water bodies were Lymnaea acuminata and Gyraulus convexiusculus and the aquatic vegetation comprised of Vallisenaria, Najas and Hydrilla species. The monthly cercarial activity was highest in Fasciola spp recovered from L. acuminata in the month of September, 2009, whereas recovery of cercariae of Fasciola spp from Gyraulus convexiusculus was highest in the month of July. The over all study results revealed that more cercariae of Fasciola were recovered from L. acuminata compared to Gyraulus convexiusculus. The plant species most successful for metacercarial deposition was Hydrilla and Najas as compared to Vallisenaria. This present study is unique in a sense that no such type of study has previously been reported especially in Potohar region, Punjab, Pakistan. These results will be the basis for developing effective control strategies of fasciolosis, based on its occurrence and to facilitate design targeted and cost effective drugs to control fasciolosis in Potohar region.