Pervasive Environmental Contamination with Human Feces Results in High Prevalence of Zoonotic Sarcocystis Infection in Pigs in the Punjab, India

Abstract

Three species of Sarcocystis-S. miescheriana, S. suihominis, and S. porcifelis-have been recorded from pigs ( Sus scrofa ). Among these 3 species, the zoonotic species S. suihominis is of paramount importance and an important food safety issue. Previous studies indicate prevalence of porcine Sarcocystis species in India, but molecular evidence, among other evidence, is required for proper species differentiation. Myocardium from 250 stray and farm pigs destined for slaughter for human consumption were collected from slaughter shops located in urban slums in Punjab, northern India. Tissues were examined for Sarcocystis by using an intact cyst isolation method, pepsin acid digestion, Sarcocystis 18S ribosomal RNA polymerase chain reaction (PCR), and real-time quantitative PCR with melting curve analysis (qPCR-MCA). The combination of primers was used for 18S rRNA PCR amplification followed by sequencing. Ten representative samples were sequenced in both the directions from which 7 readable sequences were obtained for phylogenetic analysis. Sarcocystis cysts/zoites were recorded in 146 (58.4%), 169 (67.6%), 182 (72.8%), and 191 (76.4%) of samples by using intact cyst isolation, pepsin HCl digestion, conventional PCR, and qPCR-MCA, respectively. Molecularly, 1 S. miescheriana isolate and 6 isolates of the zoonotic species S. suihominis were recorded. This is the first study providing molecular identification for the presence of zoonotic species S. suihomonis in India. The prevalence of zoonotic S. suihominis in pork in India is worrisome and warrants intervention policies to stop the practice of rearing pigs under unhygienic conditions.