Epidemiological and genotypic assessment of cystic echinococcosis in ruminant populations of Northern Punjab, Pakistan: a neglected zoonotic disease.

Echinococcus granulosus is a zoonotic dog parasite, which causes cystic echinococcosis in humans and animals, adversely affecting health and food production. The resultant socio-economic impacts in lower-middle-income countries and the paucity of epidemiology data prompted the World Health Organization to classify cystic echinococcosis as a neglected tropical disease. Between November 2019 and December 2020, the prevalence of cystic echinococcosis was assessed from 3600 post-slaughter livestock (1142 sheep, 1258 goats and 1200 buffalo) from three districts, Narowal, Sheikhupura and Sialkot, in Northern Punjab, Pakistan. The collected hydatid cysts were subjected to microscopy and PCR followed by Sanger sequencing and phylogenetic analysis. A questionnaire targeted 3600 animal owners to assess disease risk factors. Of the 28 cyst samples sequenced for mtDNA COI, the species was confirmed as Echinococcus granulosus and phylogenetic analysis revealed the presence of both G1 and G3 lineages. Overall, we noted a regional difference in prevalence, where infections were significantly higher in Sheikhupura (9.8%) than Sialkot (6.1%) or Narowal (5.9%) districts. Prevalence was higher in buffalo (9.3%) than sheep (7%) or goats (5.5%), significantly higher (9.3%) in older (> 4 years) compared to younger (< 4 years) animals (5.7%) and higher in females (9.1%) compared to males (3.8%). In sheep and buffalo, more cysts were found in the liver (77.7% and 68.7%, respectively), whereas the lungs were more commonly infected in goats (67.1%). Epidemiological data revealed that combining dog deworming with effective disposal of viscera is needed for a significant reduction in infection prevalence. Similarly, animal deworming was only associated with significantly reduced infections when the animals were not kept near an abattoir, where dogs would normally be present and feeding on discarded viscera. This study adds to growing evidence that simple public health measures and awareness are needed to reduce the prevalence of cystic echinococcosis infection.