Trichinella spp. in Slaughtered Pigs of India: From Neglected Disease to an Emerging Food Safety Threat for Public Health

Abstract

Background. In India, Trichinella nematode worm remains highly neglected due to the paucity of research. Recent trichinellosis outbreaks in humans associated with pork meal in north India have highlighted an emerging food safety concern due to this neglected parasite. Aim. This study aimed to ascertain the existence of Trichinella species and to identify them in slaughtered pigs intended for human consumption in the Punjab and Uttaranchal regions of North India. Materials and Methods. A total of 1,194 slaughter pig tongue samples were screened in 239 pools using the double separatory funnel method for recovery of Trichinella larvae. The species of recovered larvae were confirmed by multiplex PCR assay and sequencing. A phylogenetic tree was constructed to ascertain the closest lineage. Results. This study reported 3.77% and 1.26% Trichinella positivity in pooled and individual pig samples, respectively. Pigs slaughtered in Punjab reported higher positivity (1.73%) than pigs in Uttaranchal (0.81%). Among all places, Jalandhar recorded highest positivity of 5.66%, followed by 2.22% in Nainital and 0.8% in Patiala, whereas none of the pig samples from Chandigarh, Ludhiana, Bathinda, Tehri Garhwal, Pauri Garhwal, Kashipur, Haridwar was positive. Molecular confirmation by PCR and sequencing confirmed the recovered Trichinella larvae as T. britovi and T. nelsoni. Conclusion. Trichinella parasite remained highly neglected in India; however, the detection of sylvatic Trichinella species in pigs intended for human consumption indicated the emergence of zoonotic foodborne risk at wild animal-domestic pig and human interfaces. To the best of our knowledge, this is the first study reporting T. britovi and T. nelsoni in pigs of North India. Trichinella positivity in slaughtered pigs is an early alarm for the emergence of foodborne risk from this neglected parasitic worm. Considering the importance of pigs as a source of meat and their role as a reservoir for Trichinella raised the food safety concern that warrants strict meat inspection and extensive studies on neglected parasites in India.