High prevalence of porcine cysticercosis in slaughtered pigs in Rwanda: An abattoir survey.

Porcine cysticercosis (PC) is an important public health problem, especially in sub-Saharan Africa, but limited information is available on the prevalence of infection in pigs entering the food chain. Existing diagnostic methods vary in accuracy and efficiency; whole carcass dissection is the most reliable method but is labour-intensive and destroys the carcass so can only be used in a research setting. Serological tests offer lower specificity, while meat inspection and lingual examination lack sensitivity, hampering accurate estimates and the removal of infected pigs from the food chain. Here, we provide the first estimates of PC prevalence in abattoirs in Rwanda. We use whole carcass dissection to determine the diagnostic accuracy of a commercial antigen-ELISA to estimate the true prevalence of infection across Rwanda and identify Taenia species affecting local pigs. We carried out a cross-sectional survey in 6 abattoirs across Rwanda (n = 744 pigs), with whole carcass dissection of a subset of 67 pigs. Cysts were detected in 20/67 (30%) of carcasses, with >1000 cysts in 9/20 (45%) of infected pigs. All cysts were identified as Taenia solium by PCR-RFLP, with no cysts of Taenia hydatigena found. The antigen-ELISA showed a sensitivity of 90% (95% CI: 68–99) and specificity of 85% (95% CI: 72–94), when compared to dissection. Using these estimates, the true prevalence was calculated as 25–43% in two abattoirs in south-west Rwanda, and 2–3% in the rest of the country. Fewer than half of infected pigs were detected by tongue palpation and post-mortem veterinary inspection. Our data indicate a high prevalence of PC in Rwandan abattoirs. Tongue palpation and veterinary inspections, as currently carried out, have little impact in removing cyst-infested pigs from the food chain. Additional interventions are needed, such as proper pig husbandry, treatment and vaccination against cysticercosis, health education, improved sanitation and hygiene, and improved processing and cooking of meat. Author summary: Porcine cysticercosis is a tapeworm infection with a complex life cycle involving pigs and humans. This parasite is the cause of over a third of cases of acquired epilepsy in regions of the world where sanitation is poor and free-range pigs are reared, and is a public health and economic challenge to consumers and farmers. Our study aimed to estimate the prevalence of tapeworm infection in slaughtered pigs in Rwanda, in order to support disease control. We found that porcine cysticercosis is widespread across the country with a high prevalence in the south and south-west. Pigs with very high numbers of tapeworm cysts were identified and constitute a public health concern to consumers. We showed that the locally available tests for infection such as tongue palpation and veterinary meat inspection are not efficient at preventing infected pigs from reaching consumers. Control of cysticercosis in Rwanda will require further interventions that support hygienic pig production practices and improved pork processing and cooking, ensure appropriate on-farm treatment to stop transmission of porcine cysticercosis and human taeniasis and increase community awareness and behaviour change. [ABSTRACT FROM AUTHOR]