H1N1 influenza, or "swine flu" FAQ
What is swine flu?
Generally, swine flu is a respiratory disease of pigs caused by type A influenza virus that regularly causes outbreaks of influenza in pigs.
As of April 2009, “swine flu” has come to refer to a new influenza virus causing illness in people. This new virus was first detected in people in April 2009 in the United States. Other countries, including Mexico and Canada, have reported people sick with this new virus. This virus is spreading from person to person, probably in much the same way that regular seasonal influenza viruses spread.
What makes the transmission of swine flu more rapid than seasonal flu?
All forms of influenza that are transmitted person to person are highly contagious. Every year in the United States, on average 5 percent to 20 percent of the population gets the flu. However, in the United States many people get vaccinated against seasonal flu, which results in a slower rate of transmission around the nation. It is not clear yet how rapidly H1N1 is transmitted.
Is swine flu more dangerous than seasonal flu?
Like seasonal flu, swine flu in humans can vary in severity from mild to severe. Although the vast majority of people who get seasonal flu do recover fully, each year in the United States more than 200,000 people are hospitalized from flu complications and about 36,000 people die from flu-related causes.
Deaths from seasonal influenza are usually among those at age extremes — the elderly and the very young. This is often because of weakened immune systems and other conditions. Many people who die from the flu actually die from secondary pneumonia or another condition. However, with the current H1N1 influenza strain, it is too early to know who is most at risk and if this new strain is more dangerous.
Is it possible this flu will return in flu season?
Yes, this is certainly possible. During the flu pandemic of 1918, cases began in the spring and then faded away during the summer, only to come back with a vengeance in the fall and winter. Therefore we should be prepared for a potential return of H1N1 this fall and winter either as a manifestation of the annual seasonal flu we always get, or in addition to it.
Why does this strain have the ability to spread beyond the typical months (October to April) of the flu season?
In the Northern Hemisphere, winter is the time for flu. In the United States, flu season can range from November to as late as May, encompassing parts of fall, winter and spring. But during summer, if you think you have the flu it is most likely another type of respiratory illness. However, it's not impossible to catch flu in the summer, though, and travel is often the culprit. While the flu season is associated with the winter months, remember that in the Southern Hemisphere, winter is from April through September — and so is flu season. And in the tropics, you could be at risk of flu year round because there is no defined flu season.
Is swine flu more deadly than other flu if not treated?
Thus far, in the United States the current influenza outbreak has not been deadly. The vast majority of the people infected with H1N1 have only been moderately ill.
What is the role of pig farms in this outbreak?
At this point, it is still unknown exactly how, when or where the disease originated. Many possibilities exist for how the virus jumped to humans.
The Centers for Disease Control and Prevention has not found any evidence to indicate that any of the illnesses resulted from contact with pigs.
The disease is not spread by eating pork.
What is the difference between “H1N1 influenza” and “swine flu?”
There are many different types of swine flu. Some of which are H1N2, H3N2 and H3N1. The term H1N1 identifies the makeup of this particular virus, and the use of this term in comparison to “swine flu” ensures accuracy as each particular virus is different. [LINK to http://www.cdc.gov/h1n1flu/key_facts.htm] Additionally, it has not been found in the United States that anyone infected with the virus contracted it directly from swine. Use of the term “swine flu” can mislead people to think that humans can contract swine flu from eating pork, which they can’t.
What are the symptoms of swine flu?
According to the CDC, symptoms are similar to the symptoms of regular human flu and include fever, cough, sore throat, body aches, headache, chills and fatigue. A significant number of people who have been infected with this virus also have reported diarrhea and vomiting. [LINK to http://www.cdc.gov/h1n1flu/qa.htm]
What should I do if I have symptoms?
If you live in areas where cases have been identified and develop flu-like symptoms (fever, aches, runny nose, sore throat, nausea, vomiting or diarrhea) you may want to contact your health care provider. Your health care provider will determine whether influenza testing or treatment is needed. If you are sick, you should stay home and avoid contact with other people as much as possible to keep from spreading your illness to others.
Can eating pork cause swine flu?
Swine flu cannot be transmitted by eating pork or pork products. According to CDC, cooking pork at 160ºF kills viruses, including swine flu. [LINK to http://www.cdc.gov/h1n1flu/key_facts.htm]
What is the comparison to avian flu, in terms of its severity and also in terms of how easily each spreads?
The risk from avian influenza is generally low for most people, because the viruses do not usually infect humans. However, confirmed cases of human infection from several subtypes of avian influenza infection have been reported since 1997. Most cases of avian influenza infection in humans have resulted from contact with infected poultry such as domesticated chicken, ducks and turkeys or surfaces contaminated with secretion/excretions from infected birds. The spread of avian influenza viruses from one ill person to another has been reported very rarely, and has been limited, inefficient and unsustained. This differs greatly from the current H1N1 influenza strain that is being spread from person to person. [LINK to http://www.cdc.gov/flu/avian/]
If something like 36,000 people die from the flu in a normal year, why is this virus such a big deal?
A flu pandemic occurs when a new flu virus emerges for which humans have little or no immunity and then spreads easily from person to person around the world. This is what is happening now. In the 20th century we had two mild flu pandemics, in 1968 and 1957, and the severe "Spanish flu" pandemic of 1918, which killed an estimated 40 million to 50 million people worldwide.
This virus is a concern because it is a new strain of influenza for which people have not been vaccinated nor have an immunity. It contains genes from swine flu, avian flu and human flu, and much is still unknown about it. Because of how rapidly the virus has spread around the world, health officials are taking precautions to keep people safe while they continue to learn more.
What is the possibility it will mutate and become another pandemic next year?
The influenza virus is notoriously unstable and changes rapidly. Since this is a new virus it is too early to tell. However, it does have the potential to mutate and become either more deadly or more benign.
Are certain populations — the elderly or infants — more vulnerable to the swine flu than other populations?
For more information, visit CDC’s H1N1 flu page.
updated 05/06/09
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