Distribution of Taenia saginata metacestodes: a comparison of routine meat inspection and carcase dissection results in experimentally infected calves

Abstract

A comparison of techniques for detecting the presence of Cysticercus bovis in bovine carcasses was made by using carcass dissection and routine beef inspection guidelines. In the study, 28 calves were used after they were tested and found to be negative for the presence of anti-C. bovis serum antibodies and were inoculated orally with aliquots containing 6 x 10(4) Taenia saginata eggs. One hundred and twenty days after inoculation, the animals were slaughtered and a post mortem evaluation was done following Brazilian Federal Beef Inspection guidelines. This routine meat inspection was able to identify 71.42% of the assessed infected carcasses as being parasitized. This result implies that 28.58% of the infected carcasses would have been released as fit for human consumption since they would have been considered as free of C. bovis infection when using this method for carcass assessment. Only 3.07% of the total 2311 metacestodes present in the carcasses were identified by the conventional procedures of sanitary inspection. The assessment of different parts of the carcasses showed high infestation rates in shoulder clod (14.37%), head (11.21%), neck+chuck roll (8.05%), heart (7.75%) and top (inside) round (7.18%) which, together, were responsible for housing 48.51% of all the cysts found in the 24 beef cuts assessed. These numbers contrasted to the low incidence of cysts found in organs such as tongue (3.12%), diaphragm (1.69%) and esophagus (1.60%) which are usually described as predilection sites for the parasite.