Swine flu - Q&A

A: It is a contagious respiratory disease of pigs caused by type A influenza viruses. Pigs are hit by regular outbreaks.

There are many different types of swine flu and the current cases involve the H1N1 strain of type A influenza virus.

Q: How do humans catch it?

A: While people do not normally catch it, humans can contract the virus, usually if they have been in close contact with pigs.

It is also possible for the constantly changing infection to spread from person to person, which has happened in the latest outbreak. Experts believe it spreads in the same way as seasonal flu - through coughing and sneezing.

Q: What are the symptoms?

A: The symptoms of swine influenza in people are similar to the symptoms of regular human seasonal influenza infection and include fever, fatigue, lack of appetite, coughing and sore throat.

Some people with swine flu have also reported vomiting and diarrhoea.

Q: What is the difference between swine flu, avian flu and the flu commonly seen in the UK during the winter?

A: Influenza viruses are commonly circulating in the human and animal environment, with different strains causing illness in humans, bird and pigs.

Seasonal influenza is caused by viruses that are adapted to spread in humans.

Humans have some natural immunity to the strains that are in common circulation, and this immunity can be boosted by immunisation with a vaccine.

Avian influenza is caused by influenza viruses adapted for infection in birds. Similarly, swine influenza is caused by influenza viruses adapted for infection in pigs.

However swine flu can pass between human to human, while this is rare with avian flu viruses.

Q: How dangerous is it?

A: Thousands of people have been made ill by swine flu - with some cases proving fatal.

The World Health Organisation has warned the outbreak has "pandemic potential" and countries have been advised to step up surveillance and preparation in case the infection spreads rapidly.

Flu viruses have the ability to change and mutate, making it difficult for drugs manufacturers to ensure effective vaccines are available.

The new version of the H1N1 virus is a mix of different animal and human versions of the disease. Mixing can lead to the development of changed viruses to which humans have little immunity.

However, testing has shown that the antiviral drugs oseltamavir (Tamiflu) and zanamivir (Relenza) appear to be effective against the human swine influenza H1N1 strain.

Q: What is a pandemic?

A: If the flu spreads over a wide geographic area and affects a large proportion of the population it goes beyond an epidemic and becomes a pandemic.

According to the Health Protection Agency, an influenza pandemic is defined as a new or novel influenza virus that spreads easily between humans.

When new influenza viruses are introduced into the environment, humans do not have any natural immunity to protect against them.

Therefore, there is a risk that new influenza viruses could develop into a pandemic if the virus passes easily from human-to-human.

Q: What is being done in the UK to prevent the spread of the infection?

A: Seven people who were in contact with the two infected individuals in Scotland are being "appropriately cared for" after showing "mild" symptoms which have not been confirmed as swine flu. They are receiving drugs at home, not in hospital.

The HPA has advised people to follow general infection control practices and good hygiene to reduce transmission of all viruses.

This includes covering their nose and mouth when coughing or sneezing, disposing of dirty tissues promptly and carefully, washing hands frequently with soap and water and cleaning surfaces which are regularly touched.

The Foreign Office is also advising Britons to avoid all but essential travel to Mexico.