Disease emergence and spread do not respect geographical boundaries. This is why it is important to have the necessary tools available to combat and control disease. Efficient early warning and forecasting of disease trends through surveillance systems is key to effective containment and control. Early intervention such as the use of vaccines during a disease epidemic often leads to better outcomes with reduced disease burden and associated economic impact.
H1N1 Outbreak in 2009
The outbreak of the human disease, first reported in Mexico in April 2009, was caused by a novel, reassorted influenza A virus, type H1N1, now known as the Influenza A (H1N1) virus. This virus is different from swine influenza viruses found in pigs, and it also contains genes from avian and human influenza viruses (http://www.cdc.gov/h1n1flu/qa.htm).
The strain of this Influenza A (H1N1) virus is transmitted from person to person.
There are no food-safety issues related to this Influenza A (H1N1) virus. It cannot be passed to humans through food, by eating properly cooked meat or meat products. In general, the influenza virus A is killed by temperatures of 160°F/70°C, by proper hygiene measures and by common disinfectants.
The virus was not apparent in pigs in Mexico during the initial outbreak in humans (see WHO). Scientific information available to the OIE (OIE press release on 30 April) and partner organisations indicates that the influenza A (H1N1) virus is being transmitted amongst humans primarily.
However the influenza A (H1N1) virus has meanwhile been found in pigs and turkeys. It is highly probable that the animals were exposed to the virus through farmers or farm workers. The safety of food, as explained above, is not affected and it continues to be safe to eat meat or meat products.
Q1. What is swine flu?
A1. Swine influenza is a respiratory disease in pigs caused by one of several type A influenza viruses. Mortality rates amongst pigs tends to be low (1-4%). Most commonly swine influenza viruses are of the H1N1 or H3N2 subtypes, but there are other subtypes circulating too. Pigs can also be infected with avian influenza viruses and with human seasonal influenza viruses, and can sometimes be infected with more than one virus at the same time, which allow genes from different viruses to mix, called a ‘reassortant virus’.
Although swine influenza viruses are normally species-specific and only infect pigs, they may on rare occasions cause disease in humans, but it is not common.
Q2. How does the H1N1 disease in humans first reported in Mexico relate to swine flu?
A2. The current outbreak of human disease, first reported in Mexico is caused by a reassorted influenza A virus, type H1N1 that contains genetic information from 2 different swine flu viruses, one avian flu virus and one human flu virus. (http://www.cdc.gov/h1n1flu/qa.htm). Scientific information available to the OIE and partner organizations indicates that the influenza A (H1N1) virus is being transmitted amongst humans primarily. However the influenza A (H1N1) virus has been found in pigs and turkeys. It is highly probable that the animals were exposed to the virus through farmers or farm workers. The safety of food, however, is not affected and it continues to be safe to eat meat and meat products.
Q3. What are the symptoms of swine influenza in pigs?
A3. Symptoms may include coughing (or “barking”), discharge from the nose, fever, sneezing, breathing difficulties, off their food.
Q4. How does swine influenza spread among pigs?
A4. It is mostly spread through airborne droplets (e.g. sneezing, coughing), direct and indirect contact among pigs, or with contaminated objects moving between infected and uninfected pigs. Outbreaks in pigs occur all year round, with an increase in occurrence in autumn/winter. Many countries routinely vaccinate swine populations against swine influenza.
Q5. How is the disease prevented/managed in pigs?
A5. There is no one tool that will combat the disease, but a combination of good management practices, good hygiene and vaccinations can help combat swine flu among pigs.
Q6. Can humans catch swine flu from eating pork or eating any pig-by products?
A6. There is no evidence that swine influenza can be passed to humans through food, by eating pork or pork products. The swine influenza virus is killed by cooking at temperatures of 160°F/70°C, corresponding to the general guidance for the preparation of pork and other meat.
Q7. Which countries have been affected by outbreaks in pigs?
A7. The international distribution is not clearly known, but outbreaks have been known to occur in the past across the globe.
US Centers for Disease Control and Prevention: http://www.cdc.gov/h1n1flu/
European Centre for Disease Control: http://ecdc.europa.eu/en/healthtopics/pandemic_preparedness/Pages/index.aspx
World Health Organisation: http://www.who.int/csr/disease/swineflu/en/index.html
World Organisation for Animal Health (OIE): http://www.oie.int/for-the-media/press-packs/pandemic-h1n1-2009/