Prevalence of Taenia saginata Larvae (Cysticercus bovis) in Feedlot Cattle Slaughtered in a Federal Inspection Type Abattoir in Northwest Mexico

The prevalence of bovine cysticercosis was established using routine postmortem inspection of 52,322 feedlot cattle slaughtered at 1 Federal Inspection Type abattoir (TIF 301) located in the Mexicali Valley in Baja California, Mexico. The study included 31,393 animals (60.0%) purchased and transported to Baja California from stocker operations located in 17 states of Mexico and 20,929 animals (40.0%) native to Baja California. A total of 208 carcasses showed lesions suggestive of cysticercosis, and 109 were confirmed as positive for the parasite with a prevalence of 0.21%, equivalent to 2.1 cases/1000 carcasses inspected, 2.8 cases/1000 carcasses for cattle purchased in other states, and 1.0 cases/1000 carcasses for cattle native from Baja California. The sensitivity of the postmortem inspection, when compared to a gold standard of stereoscopic microscopy, was 52.4%. The prevalence of cysticercosis was 2.8 times higher in cattle from other states compared with those native to Baja California. Cysticerci were most frequently found in the heart, followed by liver and masseter muscles. In cattle from other states, 96.6% of cysticerci were classified as calcified and <4% as viable; in cattle native to Baja California, 29% of cysticerci were classified as calcified and 71% as viable. The prevalence of bovine cysticercosis established at TIF 301 was found to be 28% lower than a previous report for Baja California. However, given the sensitivity of the postmortem inspection calculated between 10% and 50%, it is possible that an undetermined number of carcasses pass as being free of cysticerci and that the meat reached both domestic and international wholesale markets, increasing the possibility of human infection and causing substantial economic loss through condemnation of infected meat and trade restrictions for endemic regions.