First report of naturally acquired clinical sarcocystosis in a pig breeding stock.

A two-year-old Large White boar from a pig breeding stock in an indoor farm in Switzerland presented anorexia, reduced general condition and fever. Despite antibiotic and anti-inflammatory treatment, the boar developed severe dyspnoea and cyanosis, and died after 4 days. At necropsy, no gross lesions were observed. Histopathologically, multifocal degeneration and necrosis of myocardial fibers with interstitial edema, severe multifocal non-suppurative myocarditis and hepatitis, and non-suppurative interstitial nephritis were observed. In heart samples, groups of organisms resembling apicomplexan tachyzoites were seen associated with the lesions. A PCR using the primers COC1-COC2 that target a conserved region of the small-subunit rRNA gene of Apicomplexa was performed with DNA from paraffin-embedded tissues. An amplification product of about 350 bp was obtained from heart samples. A sequence analysis showed 100% identities with GenBank sequences reported for Sarcocystis miescheriana. The histopathological observations and molecular findings in combination with the clinical signs, and absence of other pathologic agents highly suggested that an acute infection with S. miescheriana was the cause of death in this boar. To our knowledge, this the first report of fatal acute sarcocystosis after natural infection in a pig breeding herd.

Validation of a method for the detection of virulent Yersinia enterocolitica and their distribution in slaughter pigs from conventional and alternative housing systems.

Various methods have been described in the literature for the detection of virulent Yersinia enterocolitica in pigs. The risk factors for pig herd contamination have yet to be determined. The objective of this study was to validate a sensitive method for the detection of Y. enterocolitica and to describe the distribution of the bacteria in pigs at slaughter from conventional and alternative ("organic") housing systems. First, samples were collected from tonsils, caecum with caecal contents, and the caecal lymph nodes of 60 slaughter pigs. These samples were used to compare the sensitivity of six different laboratory culture methods either in common use or described in the literature with that of a polymerase chain reaction with two primer pairs (multiplex PCR). Then, only PCR was used to examine tonsils, caecum and caecal lymph nodes from two groups of slaughter pigs: 210 from six conventional fattening farms and 200 from three with alternative housing. The results of the multiplex PCR were positive in 28 cases. All culture methods proved inferior to PCR in sensitivity. In the second part of the study, PCR detected 36 (18%) positive pigs from alternative housing and 60 (29%) from conventional housing (p<0.05). The highest rate of Y. enterocolitica contamination was found in tonsils (11% alternative, 22% conventional; p<0.05), followed by caecum (5%, 11%) and lymph nodes (2%, 7%). The housing system appears to be one important factor in the prevalence of this common pathogen in pig herds, as we found important differences between the two systems studied here. In the conventional system, the main risk factors appeared to be sourcing pigs from different pig suppliers, use of commercial feed and transportation to slaughter.