Serological and coprological analyses for the diagnosis of Fasciola gigantica infections in bovine hosts from Sargodha, Pakistan.

Abstract

A serological and coprological survey of fasciolosis was conducted in bovine hosts from the Sargodha district, Pakistan using excretory-secretory (ES) antigens of Fasciola gigantica from cattle and buffaloes. Livers, faecal and blood samples of 146 cattle and 184 buffaloes were collected from slaughterhouses and examined for the presence of any Fasciola in bile ducts and ova in faeces. Serum was separated. ES antigens were prepared by incubating adult Fasciola in phosphate-buffered saline for 6-8 h and then filtering using a 0.22-μm syringe filter. Checkerboard titration was performed and optimum concentrations of antigen and serum were determined. Sero-prevalence was found to be 50.00 and 38.35% in buffalo and cattle, respectively. Using liver examination as the gold standard, enzyme-linked immunosorbent assay (ELISA) sensitivity was found to be 100% in both buffalo and cattle as compared with that of coprological examination in buffalo (61.79%) and cattle (54.54%). This indigenous ELISA was also highly specific, with values of 96.84 and 98.90% in buffalo and cattle, respectively. Positive predictive values were calculated as 96.74 and 98.21% in buffalo and cattle, respectively, while negative predictive values were 100%. For the validation of indigenous ELISA in field surveys, faecal and blood samples were collected from six sub-districts (tehsils) in the district of Sargodha. Sera were screened for the presence of anti-fasciola antibodies using both the indigenous and commercial ELISA kits. While both kits were equally sensitive, the indigenous ELISA was found to be more specific. The highest prevalence of fasciolosis was found in December, as ascertained using both serological and coprological examination. Significant differences were found in prevalences of fasciolosis in different sub-districts and age groups, together with feeding and watering systems.