Occurrence of Taenia-saginata cysticercosis in slaughtered cattle in north of Italy. Results of a ten-year monitoring program

The aim of this study was to provide data to estimate the prevalence of cysticercosis in cattle presented for slaughtering in the region and the trend in the last ten years. Further, it is attempting to show the value of the data recorded in slaughterhouses for epidemiological studies of T. saginata-cysticercosis in order to break the life cycle of this parasite. The observations were made in two abattoirs of the Ravenna province in North of Italy in the period 1993-2003 (abattoir A) and 1998-2003 (abattoir B). A total of 251,658 carcasses were inspected according to procedure defined by Directive 64/433/EEC as last amended. Histological examination of lesions was used to support the diagnosis in some cases when degenerated cysts could not be easily discriminated by other nodular lesions in muscles. The traceability of animals presented for slaughter was assured by documents that accompany the animals and their passport number. Occurrence of opaque and pearl like lesions, often degenerated/calcified, but occasionally showing a typical cystic pattern consistent with Cysticercus bovis (presumably over 15 weeks of infection) was observed in 185 out of 182.877 carcasses in the abattoir A and in 42 out of 68781 carcasses in plant B. Mean prevalence ranged from 0.65 to 1.79 per thousand in plant A and from 0.39 to 0.97 per thousand in plant B. These figures are comparable with those reported in surveys carried out in other European country and are consistent with use of feed lots husbandry system, which is common in Italy (SCVMPH, 2000). Findings were more frequent in hearth (64.9%) and masseter muscles (31.3%) seldom in tongue (5.4%) and diaphragm (1.1%). Cattle were considered lightly infected, because lesions were never observed in two or more of the usual inspection sites, therefore veterinarians have judged carcasses had to be treated by freezing. The histological examination has confirmed in most cases the diagnosis. The origin of the infected animals slaughtered in 2000-2004 in slaughterhouse ‘A’ was investigated and it was observed that half of the infected animals were from six farms, that is to say less then ten percent of farms presenting cattle for slaughtering in that plant were involved in 45/90 cases of cysticercosis detected at post-mortem inspection. It was showed that a single farm was involved in 21/90 cases. These figures led to investigate the origin and the possible causes of the high prevalence in these farms. All of them use to acquire calves six-twelve months old and rear them for meat production. Lesions found at post-mortem inspection could be consistent with infection events occurring in the free husbandry period of veal and 39 of the 90 infected cattle were not borne in Italy. Although ear-tags and passports of animals showed that most of these cattle were borne in six provinces of France, the hypothesis that the place where veal were born and reared was the place where infection has most probably occurred could not be supported. Enquire in the farm showing the highest prevalence indicate that all calves were grouped in France in two weaning centres and that the infected animals were from one of these centres. It was also observed that during the last twelve months the infection is persisting in the farm showing the higher prevalence. Several studies have reported that cattle became infected by grazing pastures in close proximity to municipal sewage treatment plants or use of sewage sludge as a fertilizer, which is restricted by regulations. In these studies the incidental increase of cases of cysticercosis has initiated the investigations. In a similar way evidence of relatively high prevalence of cysticercosis in specific farms observed at post-mortem inspection should alert the veterinary public health authorities responsible for controlling the farms of origin of the infected animals and use of serological surveys is advised.