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| Swine Flu |
The 2009 outbreak of influenza A (H1N1) virus is an epidemic of a new strain of influenza virus identified in April 2009, commonly referred to as "swine flu." Although the source of the outbreak in humans is still unknown, cases were first discovered in the U.S. and officials soon suspected a link between those incidents and an earlier outbreak of late-season flu cases in Mexico. Within days hundreds of suspected cases, many of them fatal, were discovered in Mexico, with yet more cases found in the U.S. and several other countries in the Northern Hemisphere. Soon thereafter, the U.N.'s World Health Organization (WHO), along with the U.S. Centers for Disease Control and Prevention (CDC), expressed concern that the A(H1N1) could become a worldwide flu pandemic, and WHO then raised its pandemic alert level to "Phase 5" out of the six maximum, as a "signal that a pandemic is imminent".
Although virologists have noted that the outbreak has proven relatively mild and less fatal than historic pandemics, other health officials, including CDC Director Richard Besser, worry about what might happen later in the year, stating that "we are not seeing any sign of this petering out. We are still on the upswing of the epidemic curve. The number of cases is expected to rise as the new flu spreads across the country."
The new strain is an apparent reassortment of four strains of influenza A virus subtype H1N1. Analysis by the CDC identified the four component strains as one endemic in humans, one endemic in birds, and two endemic in pigs (swine). However, other scientists have stated that analysis of the 2009 swine flu (A/H1N1) viral genome suggests that all RNA segments are of swine origin, and "this preliminary analysis suggests at least two swine ancestors to the current H1N1, one of them related to the triple reassortant viruses isolated in North America in 1998." One swine influenza ancestor strain was widespread in the United States, the other in Eurasia.
Swine Flu . . . . . .
Swine flu is a form of influenza that originated in pigs but can be caught by, and spread among, people.
Swine flu is a respiratory disease of pigs caused by type A influenza viruses. Outbreaks of swine flu happen regularly in pigs. People do not normally get swine influenza, though infections do sometimes happen. In the recent past, most human cases of swine influenza have been in people who were in close contact with pigs, such as farmers. In the current outbreak the virus has been spread by person-to-person contact.
In the current swine flu outbreak, human infection with swine influenza A (H1N1) viruses has also been confirmed in the US, Canada, the UK, and other countries.
This has given rise to concern that the outbreak could become a pandemic flu - a global outbreak of flu that spreads quickly because it is a new type of virus that few, if any, people have resistance to.
A flu pandemic is a natural event that occurs from time to time. Last century, there were flu pandemics in 1918, 1957 and 1968, when millions of people died across the world.
Experts warn that another flu pandemic could happen soon, but they do not know when.
How is swine flu different from seasonal flu or bird flu?
Seasonal flu, caused by an existing flu virus, is a common infection in the UK that usually occurs during a two-month period in winter. For most people, it is an unpleasant but not life-threatening infection. People who are more at risk from it, such as older people, can be given a vaccine each year (see Useful links, right).
Bird flu, also known as avian flu, is influenza that, as its name suggests, is usually confined to birds. However, like swine flu, it can also sometimes be caught by people and by pigs.
If swine flu or bird flu do spread in people, it can be very serious and can cause death.
A pandemic occurs when a new flu virus appears in the human population and spreads from person to person worldwide. It is likely that such a virus will be caused by a bird or animal virus mixing with the human virus (see Causes).
It is expected that an outbreak of pandemic flu will cause more illness and many more deaths than ordinary flu.
Is a flu pandemic imminent?
A pandemic could happen any time, but we cannot predict exactly when it would start. The swine flu virus could lead to a pandemic. The World Health Organization (WHO) is closely monitoring cases of this new flu virus.
The WHO has defined stages in the progression of a pandemic. We are currently at Phase Five of six phases (a pandemic is confirmed at Phase Six).
What can we do?
The single most effective way to stop or slow the spread of diseases such as swine flu is to prevent the spread of germs. Wash your hands regularly with soap and water and cover your mouth if you cough or sneeze (see Prevention for more detailed information).
You should also think about what you would do if you and your family all became ill. Who could you rely on for support, such as to collect medicines or shop for you?
What is an epidemic and a pandemic?
An epidemic is a sudden outbreak of disease that spreads through a single population or region in a short amount of time.
A pandemic occurs when there is a rapidly-spreading epidemic of a disease that affects most countries and regions of the world.
What is swine flu Exactly?
Go to NHS Choices for health advice on swine flu, including the latest advice on symptoms, prevention, treatment and causes
Swine flu - NHS Choices Opens new window Swine flu, or influenza A (H1N1), is a respiratory disease that infects pigs and is caused by a flu virus. There are regular outbreaks of swine flu in pigs, which become ill but rarely die from the virus. Swine flu does not normally infect humans although this does occasionally happen when people have had close contact with pigs.
There is evidence that swine flu is spreading from person to person, which could lead to what is called a 'pandemic flu outbreak'. Pandemic flu is different from ordinary flu because it is a new strain of the virus that appears in humans and spreads quickly from person to person worldwide.
The World Health Organisation (WHO) is closely monitoring cases of swine flu to see how it develops.
Who is at risk?
Swine flu is a new virus so no-one will have immunity to it and everyone could be at risk of catching it. This includes healthy adults as well as older people and children.
What is pandemic flu?
Pandemic flu occurs when an influenza virus emerges that is so different from previously circulating strains that few, if any, people have any immunity to it. This allows it to spread widely and rapidly, causing serious illness.
Ordinary flu and pandemic flu – the differences
The differences between ordinary flu and pandemic flu include:
Ordinary flu
occurs every year during the winter
affects 10 to 15 per cent of the UK popuation
most people recover within 1 or 2 weeks without medical treatment
can be identified in advance and a vaccine can be made (this immunisation is known as the flu jab and helps protect people from ordinary flu)
Pandemic flu
occurs during any season
affects more people than ordinary flu (up to half the population)
is a more serious infection
people of all ages may be at risk of infection
a vaccine cannot be made because the virus strain has not been identifed
antiviral medicine is stockpiled to treat people
Symptoms
Flu symptoms can include:
fever
cough
headache
weakness and fatigue
aching muscles and joints
sore throat
runny nose
In the case of pandemic flu, these symptoms are likely to be worse.
Swine Flu Advice |
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