Statement on Food safety considerations of novel H1N1 influenza virus infections in humans
Olivier Andreoletti, Herbert Budka, Sava Buncic, John D Collins, John Griffin, Tine Hald, Arie Hendric Havelaar, James Hope, Günter Klein, James McLauchlin, Winy Messens, Christine Müller-Graf, Christophe, Nguyen-The, Birgit Noerrung, Luisa Peixe, Miguel Prieto Maradona, Antonia Ricci, John Sofos, John Threlfall, Ivar Vågsholm, Emmanuel Vanopdenbosch.
Acknowledgment
EFSA wishes to thank the members of the Working Group on Food safety considerations of novel H1N1influenza virus for the preparation of this opinion: J. Dan Collins, John Sofos, Ivar Vagsholm and EFSA’s staff member Ernesto Liebana for the support provided to this EFSA scientific output.
Contact
biohaz@efsa.europa.eu
A new Influenza A virus in humans was notified to World Health Organisation by Mexico in April 2009. The pandemic virus contained a novel combination of genes from pig, avian and human influenza viruses. In view of public concern with respect to the safety of animal origin foods, the BIOHAZ Panel have addressed the questions: (1) state-of-knowledge on the tissue distribution and shedding of the novel H1N1 (nH1N1) influenza virus in pigs, and its possible foodborne transfer to humans; (2) aspects of the nH1N1 virus survival characteristics in foods, as well as hurdles which it must overcome in order to infect humans, in particular the alimentary tract barriers that may inactivate the virus after consumption of possibly contaminated products; and (3) identification of gaps in scientific knowledge. Pigs are fully susceptible to the nH1N1 virus. No contact infections have been reported from swine to humans. The infection in swine is respiratory with no virus dissemination to muscles or edible organs. Low-level virus contamination of meat by respiratory secretions from infected pigs may be possible at slaughter or processing. If ingested with food, the virus has to overcome several hurdles such as acidic pH in the stomach and bile salts in the duodenum, which reduce the infectivity. As oropharyngeal tissues are known ports of entry for mammalian influenza viruses, food that passes such tissues, if contaminated with nH1N1 virus, could hypothetically transmit a respiratory infection to humans. Presently, there is no epidemiological evidence that this theoretical possibility has contributed to the spread of this infection. Normal cooking procedures inactivate the virus in food. Commercially available disinfectants used for cleaning of equipment after contact with meat products rapidly destroy influenza viruses. The panel concluded that food contaminated with nH1N1 influenza viruses does not appear to be a vehicle for infection in humans.
© European Food Safety Authority, 2010
The European Food Safety Authority (EFSA) asked the Panel on Biological Hazards to conduct a review of the available information on the potential of transmission of the new (2009) nH1N1 human influenza pandemic virus to humans via food. Specifically, the BIOHAZ Panel was asked to examine the state-of-knowledge concerning the distribution and shedding of the nH1N1 influenza viruses in pigs, and possibly other food-producing animals, and the possible transfer of the virus to humans via food; evaluate aspects of the nH1N1 virus survival characteristics in food and animal by-products, as well as hurdles which the virus must overcome in order to infect humans; and identify gaps in current scientific knowledge.
As a consequence, a working group (WG) was established to draft this Statement for consideration by the Biological Hazards Panel. The WG based its Statement on a Scientific Report of the available scientific literature in the different areas specified in the terms of reference. The full report is published on EFSA’s website , and is also included as Appendix A to the Statement.
The new virus consists of a genetic reassortment of viruses, which have been circulating in pigs in Europe, Asia and North America, and it contains genes from swine, avian and human influenza viruses in a, not previously identified, combination. However, there is no evidence suggesting that the nH1N1 virus behaves in pigs in a different way than other classical influenza viruses of pigs, all of which cause only a mild respiratory disease. The nH1N1 virus spreads readily and globally among humans, requiring no contact with swine, and, therefore, it is regarded as a human influenza virus. Though proof is lacking, genetic data indicate that the nH1N1 virus most likely has the potential to spread from pigs to humans. However, several factors may contribute to the lack of swine-to-human transmission in the field or the lack of reported cases.
Based on the findings of the report: (i) Swine are fully susceptible to the nH1N1 virus and may become infected after contact with infected humans, but no contact infections have been reported from swine to humans; (ii) The infection in swine is purely respiratory with no viraemia or virus dissemination to muscles or edible organs; (iii) Low virus quantity contamination of food, including pork or pork products could be introduced by respiratory secretions containing nH1N1 virus during slaughter or handling; (iv) If ingested with food, the number of viable influenza virus particles will be reduced by acidic pH in the stomach and bile salts in the duodenum; (v) There is no evidence that the human gastro-intestinal tract tissues can serve as a portal of entry or as a target organ for mammalian type A influenza viruses, including nH1N1; (vi) As oropharyngeal tissues are known ports of entry for mammalian influenza viruses, food that passes such tissues, if contaminated with nH1N1 virus, could hypothetically transmit an infection to humans; normal cooking procedures inactivate the virus in food; (vi) Commercially available disinfectants used for sanitation of food processing equipment rapidly destroy influenza viruses; (vi) Overall, food contaminated with nH1N1 influenza viruses does not appear to be a vehicle for infection in humans.
Further research/investigation is to be encouraged in the areas identified as gaps in current scientific knowledge, which include: (i) limited information available about the global distribution for nH1N1 virus in swine; (ii) missing data on exposure to the nH1N1 virus of people in contact with pigs that appear to have influenza-like illness; (iii) knowledge on the ability of influenza viruses to replicate in cells of the intestinal tract of humans, including factors that may prevent influenza virus replication in such cells; (iv) while the oropharyngeal tissues have been shown as a port of entry for influenza viruses, there is lack of knowledge about whether passage of contaminated food would constitute a possibility for transmission; (v) information on the potential infectivity and virulence of nH1N1 and its variants from food-producing animals other than swine. In addition, all possible transmission pathways including food-borne pathways should be considered whenever new outbreaks of pandemic influenza occur.
food, influenza, H1N1, swine, pork, turkey, animal by-products, transmission risk
