Swine influenza

Swine influenza is a respiratory illness caused by the type A influenza virus. It regularly causes outbreaks in pig herds. The main virus subtypes circulating in pigs in Québec are H1N1, H3N2 and H1N2.

Though rarely, the swine flu virus can be transmitted between pigs and humans or other animals. Preventing this transmission, particularly between species, continues to be important for protecting animal health and public health. It limits the risk of the virus evolving in a way that could impact pig populations or cause a pandemic.

Animal owners and keepers, veterinarians, and heads of laboratories are required to report this disease. Refer to the Reportable animal diseases page to find out who to contact.

Swine flu primarily affects domestic pigs raised on farms or kept as pets. It can also be transmitted to wild boars. In rare cases, it is also possible for the virus to spread to other animal species, like birds.

Some animals infected with swine flu may not show any symptoms, while others may show signs of acute illness, like:

• Fever
• Weakness
• Loss of appetite
• Weight loss
• Difficulty breathing
• Coughing
• Sneezing
• Nasal discharge
• Reduced fertility
• Abortion
• Eye redness or inflammation

Although the disease can affect entire pig herds, it has low mortality rates.

Pig herds can be contaminated by other infected pig herds. Swine flu can be introduced into a herd through the arrival of an infected animal, or through contact between the herd or their environment and a sick human or contaminated hands, boots or equipment.

After one to three days, clinical signs appear and last less than a week, unless the pig contracts another infection or develops complications. Pigs become contagious 24 hours after infection and remain contagious for 7 to 10 days.

Viral shedding occurs through respiratory droplets, which are spread by coughing, sneezing and nasal discharge. The virus can be found on surfaces and in the air as aerosols at the time of shedding.

Pig herds can also be contaminated by a human- or bird-borne virus, though it is less common. For example, during the H1N1 influenza pandemic in humans in 2009, the virus spread between humans and pigs. The H5N1 virus responsible for avian influenza has also been detected in pigs without symptoms that had been exposed to infected poultry.

There is no specific treatment for swine influenza.

Supportive treatment can be administered to treat the symptoms of the disease. For example, an anti-inflammatory can be administered to fight off fever. Antibiotics can also be used as needed to control secondary bacterial infections, like pneumonia.

Several measures can help prevent swine flu in animals.

• Wear herd-specific clothing and boots.
• Wash your hands regularly.
• Develop and implement a herd-specific biosecurity program with the help of your vet.
• Restrict access to essential visitors only, and keep a visitors’ log. Make sure that all visitors are aware of the hygiene, personal protection and biosecurity practices used with the herd.
• Vaccinate pigs for swine flu.
• Monitor for signs of influenza in pigs.

To prevent the introduction of avian viruses, pig herds should be kept from contact with poultry, wild birds and contaminated material, like equipment or surface water.

Avoid contact between people with flu-like symptoms and pigs to reduce the risk of human-to-pig transmission. If it is not possible to prevent contact, individuals interacting with herds should be required to wear a procedural mask. Vaccinating workers against the seasonal human flu can limit the risk of spreading the virus to animals.

Swine industry workers must be especially well informed about what measures to take. That’s why it’s recommended to put up this poster about influenza (PDF 667 Kb) (in French only) in the workplace.

Swine influenza symptoms are similar to seasonal flu symptoms.

Cases of swine flu in humans are rare, most often occurring in workers who come in close contact with pigs or their immediate surroundings.

There is no evidence that the virus can be transmitted to humans through properly prepared and cooked pork or pork products. Continue to follow standard guidelines to prevent food poisoning (in French only).

Prevent pig-to-human transmission

To prevent transmission, it is important to wash your hands with soap and hot water after any contact with a pig. If you are unable to, clean your hands with an alcohol-based hand rub.

On farms, measures taken by workers to protect pigs from swine flu also help to reduce the risk of pig-to-human transmission.

Proper personal protection measures include wearing clean outer clothing, gloves and boots on the farm, as well as changing them and then washing your hands after leaving a building.

Wear gloves, eye protection (goggles or face shield) and an N95 mask if any of your pigs show signs of swine flu.

The Réseau porcin (French only) conducts swine influenza surveillance in Québec. Identifying which strains of a virus are circulating among pig populations also helps more effective vaccines to be produced. Veterinarians are invited to submit samples from any pigs showing signs of the disease for analysis, subsidized by a government program.