Carcass Inspection for Zoonotic Diseases

Thorough PMI of carcasses/meats (head, pluck, organs and muscles) was conducted as described by Biffa et al. [37 (link)] and Woldemariyam et al [38 (link)] to determine the presence of lesions of common zoonotic or economically important livestock diseases such as bovine tuberculosis, contagious bovine pleuro-pneumonia, porcine cysticercosis, contagious caprine pleuro-pneumonia and fascioliasis. A minimum sample size of 385 for each of the animal/carcass types was computed for the purposes of PMI study, using the Raosoft^® sample size calculator freely available online at http://www.raosoft.com/samplesize.htm. The sample size computation assumed 50% prevalence (since there is no report on the prevalence of the lesions in the Southeast Nigeria, to the best of our knowledge), 5% error margin and 95% confidence level. Carcasses inspected were randomly selected. Systematic sampling was used to select one in every five carcass (for each species: cattle, pigs or goats). However, the first carcass for each FPA type to be inspected was selected by simple random sampling (toss of coin, the display of head meant yes–to be sampled). Each selected carcass was then subjected to PMI. The PMI protocol involved visual inspection, palpation and incision of organs/tissues (massetter muscle, tongue, lungs, tracheal, liver, heart, intercostal muscle, spleen and the kidneys). Also, the retropharyngeal, tracheobronchial, mediastinal, mandibular, parotid and prescapular lymph nodes were palpated, longitudinally incised and inspected. Diseased carcasses/organs/meats were weighed and wholly or partially condemned, depending on the severity of the lesion. Whole carcass condemnation involves total condemnation while partial condemnation means passing the carcass as fit for human consumption only after the observed lesions were trimmed-off, or the carcasses were subjected to further treatment. Economic losses associated with the condemned meats were estimated based on the weight of the condemned meant and the prevailing average market prices of beef, pork, and chevon (2500 Naira/ 6 USD) in the study area. The monetary values were calculated in Nigerian Naira and converted to US dollar based on the official exchange rate of 416 Naira per US dollar.