Swine Flu in Pigs

Pig rearing is one of the main routes out of poverty for many people in Nigeria. This means that an outbreak of any sort of diseases threatens the livelihoods of thousands of families.

Swine flu is a respiratory disease caused by influenza viruses that infect the respiratory tract of pigs. Swine influenza is caused by a number of closely related influenza A viruses that are noted for their ability to change their antigenic structure and create new strains.

As a result, barking cough, decreased appetite, nasal secretions, and listless behavior are noted. The virus can be transmitted to humans. Researchers believe that influenza in other species originated from the viruses in the waterfowl reservoir.

Swine flu made headlines in 2009 when it was first discovered in humans and became a pandemic. Pandemics are contagious diseases affecting people throughout the world or on multiple continents at the same time. On October 28, 2009, the Federal Ministry of Health of Nigeria announced that the first case of swine flu had been reported in a 9-year-old American girl residing in Lagos, one of the major cities in Nigeria

Outbreaks of swine flu are most common in fall or winter, often at the onset of particularly cold weather. In warmer areas of the world,like Nigeria, infection may occur at any time. Usually, an outbreak is preceded by one or two individual cases and then spreads rapidly within a herd, mainly by aerosolization and pig-to-pig contact.

Because of its dramatic appearance, acute outbreaks of swine influenza can be fairly reliably diagnosed and treated on clinical signs.

Causes of Swine Flu

Swine influenza is caused by influenza A virus. The virus is very variable and is constantly changing its surface proteins. It can be grown in embryonated eggs or on a number of porcine cell lines.

Influenza viruses are sensitive to heat, drying, detergents and disinfectants. A number of different strains exist and are described by their H and N antigen combinations.

The virus enters the respiratory tract and multiplies rapidly within cells of the bronchial lining. Until at 24 hours post-infection most cells are infected and mucoid pus is present in the bronchioles.

Infection has largely disappeared by day 9. Infection strips the bronchial lining to stop secretions being cleared, giving rise to pneumonia and allows other respiratory pathogens to invade.

Transmission

Swine flu viruses are thought to be spread among pigs mostly through close contact and possibly from contaminated objects moving between infected and uninfected pigs. Infected swine herds, including those vaccinated against swine flu, may have sporadic disease, or may show only mild or no symptoms of infection.

Signs and Symptoms of Swine Flu in Pigs

In pigs, a swine influenza infection produces;

• fever
• lethargy
• sneezing
• coughing
• difficulty breathing
• decreased appetite.

In some cases the infection can cause miscarriage. Although mortality is usually low (around 1–4%), the virus can produce weight loss and poor growth. Infected pigs can lose up to 12 pounds of body weight over a three- to four-week period

Treatment of Swine Flu in Pigs

There is no treatment for swine influenza. Secondary infection with bacteria can be treated by injection with an antimicrobial as food and water intake is erratic during acute disease. Affected animals should have access to water and piglets with affected mothers should be provided with supplementary feeding.

Prevention

It is important to prevent any secondary bacterial infections.

• Keep sows within an environmental temperature of 20-23ºC (70-75ºF)
• Reduce all possible stress, such as draughts.
• Maintain dry bedding and floor surfaces.
• Monitor boars carefully for evidence of illness
• Identify boars that have been ill and cross-serve with another boar for the next four weeks.
• Medicate feed and water with soluble vitamins for seven days.
• Vaccinations