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Swine flu (H1N1 flu)
By Mayo Clinic staffOriginal Article: http://www.mayoclinic.com/health/swine-flu/DS01144
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Definition
The respiratory infection popularly known as swine flu is caused by an influenza virus first recognized in spring 2009, near the end of the usual Northern Hemisphere flu season.
The new virus, 2009 H1N1, spreads quickly and easily. A few months after the first cases were reported, rates of confirmed H1N1-related illness were increasing in almost all parts of the world. As a result, the World Health Organization declared the infection a global pandemic. That official designation remained in place for more than a year.
Technically, the term "swine flu" refers to influenza in pigs. Occasionally, pigs transmit influenza viruses to people, mainly hog farm workers and veterinarians. Less often, someone infected occupationally passes the infection to others. You can't catch swine flu from eating pork.
Symptoms
Swine flu symptoms in humans are similar to those of infection with other flu strains:
- Fever
- Cough
- Sore throat
- Body aches
- Headache
- Chills
- Fatigue
- Diarrhea
- Vomiting
Swine flu symptoms develop three to five days after you're exposed to the virus and continue for about eight days, starting one day before you get sick and continuing until you've recovered.
When to see a doctor
It's not necessary to see a doctor if you're generally healthy and you develop swine flu symptoms, such as fever, cough and body aches. Do call your doctor, however, if you have flu symptoms and you're pregnant or you have a chronic disease, such as emphysema or a heart condition.
Causes
Influenza viruses infect the cells lining your nose, throat and lungs. The virus enters your body when you inhale contaminated droplets or transfer live virus from a contaminated surface to your eyes, nose or mouth on your hand.
Risk factors
If you've traveled to an area where lots of people are affected by swine flu H1N1, you may have been exposed to the virus, particularly if you spent time in large crowds.
Swine farmers and veterinarians have the highest risk of true swine flu because of their exposure to pigs.
Complications
Influenza complications include:
- Worsening of chronic conditions, such as heart disease, diabetes and asthma
- Pneumonia
- Respiratory failure
Treatments and drugs
Most cases of flu, including H1N1 flu, need no treatment other than symptom relief. If you have a chronic respiratory disease, your doctor may prescribe additional medication to decrease inflammation, open your airways and help clear lung secretions.
The antiviral drugs oseltamivir (Tamiflu) and zanamivir (Relenza) can reduce the severity of symptoms, but flu viruses can develop resistance to them. To make development of resistance less likely and maintain supplies of these drugs for those who need them most, antivirals are reserved for people at high risk of complications.
High-risk groups are those who:
- Are hospitalized
- Have shortness of breath along with other flu symptoms
- Are younger than 5 years of age
- Are 65 years and older
- Are pregnant
- Are younger than 19 years of age and are receiving long-term aspirin therapy, because of an increased risk for Reye's syndrome
- Have certain chronic medical conditions, including asthma, emphysema, heart disease, diabetes, neuromuscular disease, and kidney, liver or blood disease
- Are immunosuppressed due to medications or HIV
Lifestyle and home remedies
If you come down with any type of flu, these measures may help ease your symptoms:
- Drink plenty of liquids. Choose water, juice and warm soups to prevent dehydration. Drink enough so that your urine is clear or pale yellow.
- Rest. Get more sleep to help your immune system fight infection.
- Consider pain relievers. Use an over-the-counter pain reliever such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin, others) cautiously, as needed. Don't give aspirin to children or teens because of the risk of Reye's syndrome, a rare but potentially fatal disease.
Remember, pain relievers may make you more comfortable, but they won't make your symptoms go away any faster and may have side effects. Ibuprofen may cause stomach pain, bleeding and ulcers. If taken for a long period or in higher than recommended doses, acetaminophen can be toxic to your liver.
Prevention
The Centers for Disease Control and Prevention now recommend flu vaccination for all Americans older than 6 months of age. The vaccine developed to prevent infection with the 2009 H1N1 virus is one component of the seasonal flu shot for 2010-2011. The flu shot also protects against two other influenza viruses that are expected to be the most common during the 2010-2011 flu season.
The vaccine will be available as an injection or a nasal spray.
These measures also help prevent flu and limit its spread:
- Stay home if you're sick. If you do have swine flu, you can give it to others starting about 24 hours before you develop symptoms and ending about seven days later.
- Wash your hands thoroughly and frequently. Use soap and water, or if they're unavailable, use an alcohol-based hand sanitizer. Flu viruses can survive for two hours or longer on surfaces, such as doorknobs and countertops.
- Contain your coughs and sneezes. Cover your mouth and nose when you sneeze or cough. To avoid contaminating your hands, cough or sneeze into a tissue or into the inner crook of your elbow.
- Avoid contact. Stay away from crowds if possible.
- Reduce exposure within your household. If a member of your household has swine flu, designate one other household member to be responsible for the ill person's close personal care.
- Centers for Disease Control and Prevention. Swine influenza A (H1N1) infection in two children — Southern California, March-April 2009. Morbidity and Mortality Weekly Report. 2009;58:400. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5815a5.htm. Accessed Aug. 18, 2010.
- World Health Organization. World now at the start of 2009 influenza pandemic. Statement to the press by WHO Director-General Margaret Chan. http://www.who.int/mediacentre/news/statements/2009/h1n1_pandemic_phase6_20090611/en/index.html. Accessed Aug. 18, 2010.
- World Health Organization. H1N1 in post-pandemic period. Director-General's opening statement at virtual press conference. http://www.who.int/mediacentre/news/statements/2010/h1n1_vpc_20100810/en/index.html. Accessed Aug. 19, 2010.
- Watts G. A/H1N1 influenza virus: The basics. British Medical Journal. 2009;339:b3046. http://www.bmj.com/cgi/content/full/339/jul24_2/b3046. Accessed Aug. 18, 2010.
- Centers for Disease Control and Prevention. Background information on influenza in pigs. http://www.cdc.gov/flu/swineflu/. Accessed Aug. 19, 2010.
- Centers for Disease Control and Prevention. Key facts about influenza (flu) and flu vaccine. http://www.cdc.gov/flu/keyfacts.htm. Accessed Aug. 18, 2010.
- Weber TP, et al. Inactivation of influenza A viruses in the environment and modes of transmission: A critical review. Journal of Infection. 2008;51:361.http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WJT-4TMRJXX-2&_user=130561&_coverDate=11%2F30%2F2008&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000010878&_version=1&_urlVersion=0&_userid=130561&md5=0b189b39929f3ee6cdc2ca1371fd1e0c. Accessed Aug. 19, 2010.
- Bean B, et al. Survival of influenza viruses on environmental surfaces. Journal of Infectious Diseases. 1982;146:47.
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