Q&A: Swine flu

HEALTH watchdogs are watching developments in Mexico and the US carefully after human cases of swine flu were reported. How worried should we be about the illness?

Q: What is swine flu?

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 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. These illnesses all cause the same respiratory symptoms in sufferers and can be passed between one another.

Q: How dangerous is it?

A: More than 80 people have died and thousands made ill, in Mexico in particular, although cases have also been reported in the US and New Zealand.

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

Q: Why should we be worried about it?

A: The World Health Organisation warned the outbreak had “pandemic potential” and countries were 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.

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: Will it spread to the UK?

A: It is too early to say whether the cases reported so far will lead to a larger outbreak, says the HPA. No cases have been reported in the UK, although experts are monitoring the situation closely.

Anyone who has recently returned from affected countries should consult a doctor if they notice flu-like symptoms.

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

A: The HPA says it is working with the UK government to review the current incident and any threat it poses to UK public health. It advises people to follow general infection control practices and good hygiene to reduce transmission of all viruses. This includes covering your 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.

Q: Is it safe to eat pork meat and pork products?

A: Yes. Swine influenza has not been shown to be transmissible to people through eating properly handled and prepared pork or other products derived from pigs. The swine influenza virus is killed by cooking temperatures of 160F/70C, corresponding to the general guidance for the preparation of pork and other meat.