Molecular studies on zoonotic coccidian parasites in pigs and its public health significance
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Date
2014
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Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana
Abstract
The current study was conducted to ascertain the prevalence and to provide first molecular evidence of important coccidian parasite in pigs viz Sarcocystis suihominis, Toxoplasma gondii and Cryptosporidium spp. in Punjab, India. A total of 250 pig tissue samples were collected from three different districts of Punjab and examined using intact cyst isolation method, pepsin digestion method, conventional PCR and Real time PCR melt curve analysis. Prevalence of Sarcocystis in pigs was found to be 58.4, 67.6, 72.8 and 76.4% using intact cyst isolation method, pepsin digestion method, conventional PCR and Real time PCR melt curve analysis, respectively. Histopathologically, both thick and thin walled sarcocysts were seen in tissues of infected pigs. Phylogenetic analysis of the 18s rRNA gene of Sarcocystis sequences revealed that S. suihominis is widely prevalent among Indian pigs. In Real time PCR melt curve analysis, mean melting temperature for Sarcocystis suihominis and S. miescheriana was 82.57 (82.33 82.73) and 82.21 (82.10 82.34), respectively. The real time PCR melt curve analysis could not differentiate between S. suihominis and S. miescheriana based on melt curve analysis. T. gondii cysts were not detected in 250 muscle samples examined using Real time PCR melt curve analysis. Hence prevalence of Toxoplasma in pork samples was less than 1/250 in pork samples. A total of 265 faecal samples of pigs were collected and examined using faecal floatation method alone and along with Modified Ziehl Neelson (mZn) acid fast staining techniques. None of the samples were found positive for Cryptosporidium spp oocysts in pig faecal samples. However with faecal floatation method, other gastro intestinal parasites such as Ascaris, unsporulated oocysts, Trichuris, Macrocanthorynchus and Strongyloides were recorded in 27.5, 15.4, 1.8, 0.75 and 4.5 per cent pig faecal samples. The results indicated that Real Time PCR Melt curve analysis can efficiently detect coccidian cysts from muscle samples. The results further indicate that S. Suihominis is widely circulating among Indian pigs and is an important public health hazard in India. High prevalence of Ascaris eggs in pig feacal samples demands that further studies must be done to ascertain the public health significance of ascariosis in India