Consultation on potential risks of pandemic (H1N1) 2009 influenza virus at the human-animal interface
As a result of the current outbreak of pandemic (H1N1) 2009, many questions have been raised about the risks to people from exposure to pigs and pork products. Likewise, the need to estimate the risk to pigs from contact with infected people has been highlighted. To assess these risks based on available scientific data, the World Health Organization (WHO), the Food and Agriculture Organization (FAO) and the World Organisation for Animal Health (OIE) hosted a scientific consultation via teleconference on 3 June 2009. Since the emergence of the current pandemic strain, knowledge and available scientific information about the pandemic virus is constantly being expanded. Available information to date suggests that the current pandemic strain in pigs is similar to other known influenza viruses that affect swine, in terms of clinical manifestations, epidemiology and biochemical properties. For this consultation, however, some of the recommendations had to be extrapolated from what we already know about other influenza viruses that infect swine and other hosts.
The expert WHO/OIE/FAO consultation made the following consensus statements.
- Humans can become infected through close contact with ill pigs infected with influenza virus and showing influenza-like signs. This is presumed to be true for pandemic (H1N1) 2009 virus as well. Such occurrences are rarely documented through current surveillance systems.
- The risk of humans becoming infected from contamination reaching the environment (e.g. through manure) is minimal as influenza viruses are not usually shed in the faeces of the pig.
- The risk of being infected with swine influenza viruses through the consumption of pork or pork products is considered negligible. Influenza viruses are generally restricted to the respiratory tract of pigs and are not detected in the muscle (meat) of pigs, even during acute illness. Heat treatments commonly used in cooking meat (e.g. 70°C/160°F core temperature) will readily inactivate viruses and other pathogens potentially present in raw pork products.
- People ill with influenza have reportedly infected pigs with influenza viruses. While this is possible, these events are not well documented. Those working with pigs should follow the same advice as provided to the general public and stay home if they exhibit flu-like symptoms.