Swine flu is spread to humans primarily through contact with infected pigs.
The disease is spread among pigs by direct and indirect contact, aerosols, and from pigs that are infected but do not have symptoms. In many parts of the world, pigs are vaccinated against swine flu.
Most commonly, swine flu is of the H1N1 influenza subtype. However, swine flu viruses can sometimes come from other subtypes, such as H1N2, H3N1, and H3N2.
The 2009 outbreak of swine flu that infected humans was of the H1N1 subtype. It is important to note that, although it developed in swine, the 2009 pandemic virus was not completely derived from swine. The virus contains a combination of flu genes from avian (bird), swine, and human flu types.
At the time, it was classed as a pandemic, but now it is simply considered a normal human flu virus.
Here are some key points about swine flu.
- Swine flu is normally of the H1N1 influenza subtype.
- The most common way for a human to catch swine flu is through contact with a pig.
- There is currently no human vaccine for swine flu.
- Symptoms of swine flu include coughs, chills, and aches, similar to seasonal flu.
How does a human catch swine flu?
There are only a few causes of swine flu in humans. They are:
Contact with infected pigs - this is the most common way of catching swine flu. Any contact with infected pigs makes transmission more likely.
Contact with infected humans - this is a much less common way of catching swine flu, but is a risk, especially for those in close contact with an infected person. In cases where humans have infected other humans, close contact was necessary with the infected person, and it nearly always occurred in closed groups of people.
Some people are more at risk of catching swine flu than others; including:
- people aged over 65
- young children (under 5)
- people with chronic diseases
- pregnant women
- teenagers receiving long-term aspirin therapy
- anyone with a compromised immune system
Treatments for swine flu
There are some drugs available that can effectively treat swine flu infection in humans as well as many other types of flu infections in humans.
There are two main treatments:
- Adamantanes (amantadine and remantadine).
- Inhibitors of the influenza neuraminidase protein (oseltamivir and zanamivir).
Most people with swine influenza recover completely without the need for medical attention.
Prevention of swine flu
As there is no known single cure, prevention of swine flu is an effective method of avoiding outbreaks. There are a number of steps that can be taken to help prevent the spread of swine flu:
- Washing hands regularly with soap.
- Getting plenty of sleep.
- Doing plenty of exercise.
- Managing stress.
- Drinking liquids.
- Eating a balanced diet.
- Refraining from touching surfaces that may have the virus.
- Do not get close to people who are sick.
- Stay away from crowds if there is a swine flu outbreak in your area.
If I am infected with swine flu, how can I stop others from becoming infected?
If a patient is infected, it is important they follow these rules to prevent any further spread:
- Limit contact with other people.
- Do not go to work or school.
- When coughing or sneezing cover the mouth with a tissue. If there is no tissue available, cover the mouth and nose.
- Put used tissues in a trash can.
- Wash the hands and face regularly.
- Keep all surfaces that are touched clean.
- Follow all doctors' instructions.
Symptoms of swine flu in humans
The symptoms of swine flu in humans are quite similar to those of regular flu, and include:
- body aches
- diarrhea (less common)
- sore throat
- temperature (fever)
- tiredness (fatigue)
- vomiting (less common)
Symptoms can be managed with similar treatments to regular flu. However, a doctor should examine the patient for confirmation of swine flu and advise individual symptom relief.
Swine flu facts
It is still perfectly safe to eat pork products, so long as they are cooked properly.
Viruses from pigs do occasionally cause outbreaks of human infection.
Symptoms are generally similar to seasonal human influenza - this can range from mild or no symptoms at all, to severe and possibly fatal pneumonia.
Because swine flu symptoms are similar to those of seasonal flu, swine flu in humans is often not detected. If it is found, it is normally during seasonal influenza surveillance.
If symptoms are mild, it is extremely unlikely that any connection to swine influenza is found - even if it is there.
Examples of swine flu infecting humans
Since the World Health Organization's (WHO's) implementation of IHR (2005) in 2007, they have been notified of swine influenza cases from the United States and Spain. In March to April 2009, human cases of influenza A swine fever (H1N1) were first reported in California and Texas.
Other states also reported cases later on. A significant number of human cases during the same period were also reported in Mexico - starting just in Mexico City, but then throughout various parts of the country. More cases are being reported in Canada, Europe, and New Zealand - mainly from people who have been in Mexico.
Can I eat pork meat and pork products?
If the pork meat and pork food products have been handled properly, transmission of swine influenza to humans is not possible. Cooking pork meats to a temperature of 160°F (70°C) kills the virus. So the answer is "yes," pork meat and pork food products are safe to eat.
Where have pigs been infected with swine flu?
As swine influenza infection among pigs is not an internationally notifiable disease we cannot be completely sure. Swine influenza infection among pigs is known to be endemic in the United States. Outbreaks have also occurred in other parts of North America, South American, Europe, Africa, China, Japan, and other parts of Asia.
Is there a pandemic risk?
People who are not in close contact with pigs generally have no immunity to the swine influenza viruses - they are less likely to be able to prevent a virus infection. If the virus infects enough people in a given area, the risk of an influenza pandemic is significantly greater.
Experts say it is very hard to predict what impact a flu pandemic caused by a swine influenza virus would have on the global human population. This would depend on how virulent the virus is, what existing immunity among humans there already is, and a number of other factors.
Do we have a specific swine flu vaccine?
No - not for humans.
Will current human flu vaccines help protect people from swine influenza infection?
We really don't know. Influenza viruses are adapting and changing all the time. If a vaccine was made, it would have to be specifically for a current strain that is circulating for it to be effective. The WHO says it needs access to as many viruses as possible so that it can isolate the most appropriate candidate vaccine.