Prevalence and distribution of Taenia solium cysticercosis in naturally infected pigs in Punjab, India.

BACKGROUND: Taenia solium (T. solium) cysticercosis remains a neglected zoonotic disease in India. The current study was planned to estimate the prevalence of T. solium porcine cysticercosis in the Punjab state of India, to compare this prevalence with the disease prevalence in pigs reared outside Punjab and to assess the distribution of the parasite in pig carcasses. METHODS: Two slaughter shops were selected in each of the 22 districts of Punjab. Pigs slaughtered on the day/s of inspection were post-mortem inspected to identify the presence of T. solium cysts. Estimated true prevalence was estimated by taking into account the diagnostic sensitivity (38%) and specificity (100%) of post-mortem inspection using the Rogan-Gladen estimator. Positive carcasses were purchased and brought to the laboratory to assess the tissue distribution of T. solium cysts and to conduct PCR targeting large subunit rRNA gene, internal transcribed spacer 1 gene, ITS1 gene and Cytochrome oxidase I gene. The selected PCR products were submitted for sequencing and phylogenetic analyses were performed. FINDINGS: We contacted 71 shop owners to achieve a sample of 44 shops for the study. We inspected 642 pigs reared in Punjab and 450 imported from other states at these slaughter shops. In addition, we sampled 40 pigs from an abattoir located in the state capital. Of the 642 pigs reared in Punjab, 9 had T. solium cysts with an apparent prevalence of 1·40% (95% CI: 0·74%, 2·64%) and the estimated true prevalence of 3.69% (95% CI: 1·95%, 6·95%). Pigs imported from outside the state had a significantly higher prevalence (odds ratio: 2·58; 95% CI: 1·12, 5·98; p-value: 0·026) as 15 of the 450 imported pigs were positive (apparent prevalence: 3.33%; 95% CI: 2.03%, 5.43%; estimated true prevalence: 8.77%; 95% CI: 5.34%, 14.28%). None of samples was positive from the pigs sampled at the abattoir in the state capital. The PCR confirmed T. solium cysts from all the 24 positive samples. We counted a median of 897 (range 526-1964) cysts per infected pig from the 19 infected pig carcasses inspected. The phylogenetic tree based on the alignment of partial cytochrome oxidase 1 sequences indicated all positive samples to be clustered with the T. solium Asian genotype. The analysis did not indicate the presence of T. asiatica in the slaughter pigs. CONCLUSIONS: Despite the underestimation of the prevalence due to missing mildly-infected carcasses, low participation and lack of representative sampling, the presence of heavily infected carcasses containing viable cysts, particularly those imported from outside the state, indicates that T. solium cysticercosis is an important food safety concern for pork consumers in Punjab, India. Measures should be taken to reduce the disease prevalence in pigs to reduce the disease burden in the public.

Molecular detection of Toxoplasma gondii in the slaughter sheep and goats from North India.

Toxoplasma gondii is an obligate intracellular parasite that infects almost all the warm blooded animals, including human beings. The disease usually remains asymptomatic but is a serious concern for pregnant women, developing foetus and immuno-compromised individuals. We collected 400 cardiac/skeletal muscle tissue samples from slaughter sheep (177) and goat (223) intended for human consumption from Punjab, Uttar Pradesh and Chandigarh states/union territory in North India. The samples were pepsin-HCl digested and DNA was extracted from all the digested samples. Nested-PCR was carried out to amplify 580bp and 531bp bands with external and internal sets of primers specific for B1 gene of T. gondii. Molecularly, six (1.5%) isolates of T. gondii were detected. In PCR, T. gondii DNA were detected from 1.69% and 1.34% of the sheep and goat samples, respectively. Three PCR amplified products were sequenced in both the directions and readable sequences were obtained. Due to a low level of polymorphism in the targeted B1 gene, the clonal lineages of different isolates could not be determined. The results indicate that T. gondii in slaughter sheep and goat presents a low food safety risk for public health in North India.