The most important pork-borne zoonotic diseases in humans such as salmonelloses and yersinioses cause only latent infections in pigs. Thus, the infection of pigs does not result in apparent or palpable alterations in the pig carcasses, according to Diana Meemken of the University of Veterinary Medicine Hannover Foundation and co-authors there and at other research institutes in Germany.

In a paper published in Preventative Veterinary Medicine, they say that this is the major reason, why the traditional meat inspection with adspection, palpation and incision is not able to control the food safety risks of today.

The objective of their paper was to evaluate a set of serological tests, which provides a classification of pig herds into 'zoonoses risk categories' as demanded by EU law and into 'herd health risk categories' by using meat juice as diagnostic specimen for ELISA tests.

Serological data that were obtained by testing meat juice samples from various pig herds were analysed as proof of the 'meat juice multi-serology' concept. For that, at least 60 meat juice samples from 49 pig herds each were taken between September 2010 and March 2011 and tested for antibodies against zoonotic pathogens (Salmonella spp., Trichinella spp., Yersinia enterocolitica and Toxoplasma gondii) and against pathogens causing production diseases (Mycoplasma hyopneumoniae, influenza A virus subtype H1N1, influenza A virus subtype H3N2 and Porcine Reproductive and Respiratory Syndrome virus, PRRSV).

Apparent and true animal prevalence, herd prevalence values and intra-herd seroprevalence values as well as the predictive values for the herd and the animal prevalence values were calculated for each pathogen and each of the 49 randomly selected herds.

The herd seroprevalence values (one seropositive sample per herd determined a 'positive herd') for Y. enterocolitica, Salmonella spp., T. gondii, M. hyopneumoniae and PRRSV were higher than 80 per cent, respectively, for the influenza A viruses between 60 per cent and 14 per cent and for Trichinella spp., zero per cent.

Although all herds were located in the same area in the northwest of Germany within a radius of 250km, the intra-herd seroprevalence values for all tested pathogens, except for Trichinella spp., varied remarkably from herd to herd.

In the case of Y. enterocolitica and T. gondii, the intra-herd seroprevalence values varied even from zero to 100 per cent. This shows that a serological risk categoristion of pig herds regarding zoonoses and production diseases is meaningful if used for risk-based decisions in the framework of the new meat inspection concept and as part of the herd health management system.

Thus, concluded Meemken and co-authors, the development of a cost-efficient, time- and labour-saving test system for simultaneously detecting various antibodies should be the next step for an extensive implementation of the meat juice multi-serology concept.

Reference

Meemken D., A.H. Tangemann, D. Meermeier, S. Gundlach, D. Mischok, M. Greiner, G. Klein and T. Blaha. 2013. Establishment of serological herd profiles for zoonoses and production diseases in pigs by 'meat juice multi-serology'. Preventive Veterinary Medicine. Available online 24 December 2013. dx.doi.org/10.1016/j.prevetmed.2013.12.006

January 2014