The flu is an upper respiratory infection caused by the influenza virus. Every year in the United States, on average:
- 5% to 20% of the population gets the flu
- more than 200,000 people are hospitalized from flu complications
- about 36,000 people die from flu
Causes
Each winter, influenza spreads around the world. The strains are usually different from one year to the next. That's one of the reasons that you need to be reimmunized for influenza every year.
The two main kinds of influenza viruses are called Type A and Type B.
You can get the flu if you breathe in infected droplets from someone who is carrying the virus. Or if you touch a contaminated surface, you may transfer the virus from your hand to your mouth or nose.
Risk Factors
A risk factor is something that increases your chance of getting a disease or condition.
Risk factors include:
All the remaining factors don’t increase the risk of getting flu, but they do increase the risk of developing complications from flu:
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Age: newborn babies and the elderly
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Women in the third trimester of pregnancy
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Diabetes
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Weakened immune systems, such as in:
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Chronic lung, heart, kidney, or blood conditions
Symptoms
Influenza symptoms usually start abruptly. They may include:
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Fever and chills
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Severe muscle aches
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Severe fatigue
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Headache
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Decreased appetite, other gastrointestinal symptoms like nausea and vomiting
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Runny nose, nasal congestion
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Sneezing
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Water eyes, conjunctivitis
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Sore throat
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Cough
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Swollen lymph nodes in the neck
Diagnosis
The doctor will ask about your symptoms and medical history, and perform a physical exam. Diagnosis of the flu is usually based on symptoms and by knowing that influenza is already striking other people in a given community. Samples of nasal secretions or a throat swab can be sent to a laboratory to confirm the diagnosis. Blood tests can be performed, but they take longer and are more expensive.
Treatment
Treatment may include:
Antiviral Medicines
Antiviral medicines include zanamivir and oseltamivir. While amantadine and rimantidine have been useful in the past for influenza type A, they have not been recommended for the 2005-2006 flu season because of resistance.
These medications do not cure the flu, but they may help relieve symptoms and decrease the duration of the illness. But, they must be taken within 48 hours of the first symptoms.
Bedrest
It is important to get plenty of rest when your body is fighting the flu.
Fluids
Drink a lot of liquids, such as water, juice, and noncaffeinated tea.
Over-the-Counter Pain Relievers
These medications are used to control fever and treat aches and pains. Adults can use acetaminophen, ibuprofen, or aspirin.
Note: Aspirin is not recommended for children or teens with a current or recent viral infection. Check with your doctor before giving a child or teen aspirin.
Decongestants
Decongestants are available as pills or nasal sprays. If you use a nasal spray, don't use it longer than 3-5 days, or you may experience an increase in congestion, called "rebound," when you stop using the spray.
Cough Medicines
These include:
Prevention
Good preventive measures include:
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Wash hands thoroughly, including use of alcohol-based gels.
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Avoid touching eyes or nose prior to washing hands.
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Avoid biting fingernails.
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Avoid sharing personal items during the flu season.
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Consider the flu vaccine.
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People with chronic metabolic disease, kidney problems, hemoglobin abnormalities, or immune system problems
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Two forms of flu vaccine are available, injectable and nasal spray (FluMist). In a recent study of 7,852 children (6-59 months old) comparing the effectiveness of these two vaccine formulations, researchers found that the nasal spray led to 55% fewer cases of influenza through a single flu season. Since slightly more young children (6-11 months old) receiving the nasal spray developed wheezing, the researchers concluded that the benefits of FluMist outweigh its risks, especially in children with a history of asthma or wheezing. Talk to your doctor about which vaccine is the most appropriate for you or your child.*
RESOURCES:
American Lung Association
http://www.lungusa.org
US Centers for Disease Control and Prevention
http://www.cdc.gov/flu/
References:
American Lung Association website. Available at: http://www.lungusa.org.
Derlet R, Lawrence R. Influenza. Emedicine website. Available at: www.emedecine.com/med/topic1170.htm. 2004.
Griffith's 5-Minute Clinical Consult. 1999 ed. Lippincott Williams & Wilkins; 1999.
Leblebicioglu H, Brook I. Influenza. Emedicine website.
National Institute of Allergy and Infectious Disease website. Available at: http://www3.niaid.nih.gov/.
Principles and Practice of Infectious Diseases. 5th ed. Churchill Livingstone, Inc.; 2000.
Updated Prevention section on 3/2/2007 according to the following study, as cited by DynaMed's Systematic Literature Surveillance: Belshe RB, Edwards KM, Vesikari T, et al. Live attenuated versus inactivated influenza vaccine in infants and young children. N Engl J Med. 2007 Feb 15;356(7):685-696.
CDC
