Interview with Prof Peter Davies: Pork safety is a crucial issue in food production and marketing worldwide. The effective management of foodborne hazards is therefore crucial. Peter Davies from the University of Minnesota, USA, is an expert in this field and will update the IPVS audience with the current achievements and future challenges regarding this important topic.
Many zoonoses – animal diseases that can be transmitted to humans – have been associated with the pig and pork industry. “To ensure the safety of pigs and pork and to improve public health it is essential to understand the level of knowledge of those affiliated with the swine industry,” explains Peter Davies, lead speaker at the IPVS. As a veterinary epidemiologist, Davies has been involved in pork safety research over 15 years, with a particular focus on the risks and management issues at farm level.
At the IPVS, Davies will ask the question: Who is responsible for what to prevent foodborne outbreaks? “It depends on the type of hazard,” explains Davies. Different responsibilities lie with different hazards and there is a different responsibility party when dealing with physical hazards such as needles leftovers or chemicals compared to enteric pathogens such as Salmonella.” But which ones are the ones to target concerning pork safety? “Parasitic hazards such as Taenia solium, Trichinella and Toxoplasma continue to be important in many developing countries,” clarifies Davies. “Humans may contract all of these agents by eating undercooked pork, but they have been either eliminated or greatly reduced in modern pork production in developed countries. Progress has been made in reducing trichinosis in pigs and human cases have greatly declined since 1950 in the USA.” Toxoplasma also remains a threat that needs to be watched, according to Davies. “Infection with the protozoa Toxoplasma gondii occurs in about 20-30% % of the human population without doing any harm, expect for pregnant women and people with an immuno-suppressed condition.”
We are not there yet
Although the prevalence of Toxoplasma in slaughter pigs in the US has gone down considerably – from over 20% (25 years ago) to about 1-2% today, Davies stresses that problems associated with Trichinella, Toxoplasma and Taenia solium remain important food safety concerns in some developing countries. The prevalence, particularly for T. solium, is even increasing in some areas as they become more urbanised and more people practice backyard production in periurban setting. People in these regions should be educated as well to be aware of the risks and how they can be managed. With respect to consumer responsibility in general Davies has a clear opinion: “Food can never be totally risk free and foodborne pathogens are killed by proper cooking. It is
important that people know that foodborne micro-organisms are all destroyed by proper handling and thorough cooking to an internal temperature of 160° F (71° Celsius).”
Communicating the risks remains a great challenge. Methicillin-resistant Staphylococcus aureus (MRSA) is one of the issues where there is great potential for public misinformation and confusion. Different strains of this notorious ‘superbug’ have been found on farms in Europe, North America and Asia. However, not all MRSA are equal and the ‘livestock associated’ strains first identified in Europe appear to mostly not contain the toxin genes responsible for staphylococcal food poisoning. Also, as this type of food poisoning is due to toxins and not an active infection, antibiotics are not used to treat it.
Gut bacteria control
The greatest future challenges lie in the getting the bacteria in the pig intestine under control. “Here we can think of the most common agents as Campylobacter, Salmonella and Listeria and Yersinia,” explains Davies. Campylobacter is normal inhabitant of the healthy gut so we can expect it will be very difficult to reduce in the animal populations, so it is important to prevent contamination of the end product. The other organisms are less prevalent but less susceptible to simple changes in farm management. Lastly, Davies advocates improved communication around foodborne outbreaks. “There is often a lot of hysteria around it. Our challenge is to effectively estimate the actual risks and ensure that the consuming public is appropriately informed and not misled by sensationalist reporting,” Davies concludes.