'Cysticercosis storm' in feedlot cattle in north-west New South Wales

Abstract

Objective: To investigate the cause of an outbreak of bovine cysticercosis (Taenia saginata) infection on a cattle property in north-western New South Wales (NSW). Methods: Cystic lesions were detected in the muscles of cattle during routine meat inspection at slaughter. These lesions were confirmed to be cysticerci of T. saginata through histology and polymerase chain reaction (PCR). Data on cattle maintenance were obtained through interviews with feedlot owners and staff. A suspect feed supplement was investigated. Results: Between 5 July to 13 December 2010, 390 feedlot cattle from north-western NSW were slaughtered in abattoirs in NSW and Queensland. Of these, 138 animals had been maintained exclusively in feedlot enclosures from 80 to 300 days. Bovine cysticercosis was discovered in 80 cattle (58%, 26 carcasses were condemned). Another 18 cattle spent 24h in the feedlot before being moved onto pasture and 1 of them was found to be infected. During the 5 months following the initial outbreak, a further 275 cattle were slaughtered; 2 of 51 heifers retained in the feedlot for a further 100 days were infected. None of the 234 animals grazed exclusively on pasture on the property were infected. Bovine cysticercosis was confirmed through examination of histological sections of muscle lesions and PCR using DNA extracted from cysticerci. No eggs of T. saginata were recovered from the feed supplement using a standard flotation method. Conclusions: The source of infection arose from rations contaminated with human faeces. All possibilities for local contamination were eliminated during the investigation. The suspected source of infection was imported copra meal, which was used as a feed supplement.