Swine Influenza - CDC Guidance
Swine influenza (swine flu) is a respiratory disease of pigs caused by type A influenza virus that regularly causes outbreaks of influenza in pigs. Swine flu viruses do not usually infect humans, but rare human infections have occurred. Swine flu viruses can cause high levels of illness in pig herds, but cause few deaths in pigs. Swine influenza viruses can circulate among swine throughout the year, but most outbreaks occur during the late fall and winter months similar to outbreaks in humans.
Transmission of swine influenza viruses from pigs to people is thought to be spread primarily via large infectious droplets expelled by a sick infected pig during coughing or sneezing to a person in close contact with infected pigs. There also is indirect evidence to suggest that swine influenza viruses can be transmitted to people through contact with infected pigs or with surfaces recently contaminated with swine influenza viruses (e.g. touching pigs or handling material contaminated with pig secretions or feces, and then touching one’s mucous membranes). A third possible mode of transmission is via inhalation of small particulates containing swine influenza virus. The relative contributions of these three modes of transmission to the spread of swine influenza viruses to humans are not fully understood.
Basic Infection Control to prevent transmission of influenza viruses from pigs to people and from people to pigs:
- Workers should adhere to recommendations for use of personal protective equipment (PPE).
- Hand hygiene should be performed after contact with animals or their environment, equipment and surfaces that are possibly contaminated with swine influenza viruses, and after removing personal protective equipment (PPE) and/or possibly contaminated clothing. Good hand hygiene should consist of washing with soap and water for 20 seconds or the use of other standard hand-disinfection procedures as specified by state government, or industry to limit the possibility of transmission of influenza viruses and other pathogens. Workers should avoid touching or rubbing their eyes, nose, and mouth when working around pigs.
- Vaccination of pigs with swine influenza vaccine that is effective against circulating strains in pigs might reduce the risk of influenza in pigs and possibly reduce the risk of people getting infected with swine influenza viruses. However, because multiple strains of swine influenza viruses might be co-circulating among the U.S. pig population and because swine influenza vaccines in pigs are not 100% effective, vaccination of pigs will not eliminate the risk of human infection from swine influenza viruses.
- Seasonal influenza vaccination of swine workers – regardless of whether or not they have a high risk condition – is important to reduce the risk of transmitting seasonal influenza viruses from ill people to pigs. It may also reduce the risk of transmitting seasonal influenza viruses from ill people to pigs.
- Antiviral chemoprophylaxis can be considered for workers in direct contact with pigs confirmed to have influenza. Chemoprophylaxis consists of taking an antiviral drug daily for the duration of time the worker is exposed to sick pigs, and for 5 to 7 days after the last known exposure.
- Workers should be educated on the need to prevent the spread of influenza viruses from ill persons to pigs. Workers also should be trained to recognize influenza-like illness signs and symptoms in humans. These include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills, fatigue, and possibly vomiting or diarrhea. A worker who has been diagnosed with influenza, or has similar influenza-like illness symptoms, or reports contact with others who have similar illness (listed above) should avoid contact with pigs.
CDC Interim Guidance for Workers who are Employed at Commercial Swine Farms: Preventing the Spread of Influenza A Viruses