Flu

Definition

The flu is a respiratory infection caused by the influenza virus.

The Upper Respiratory Tract

© 2008 Nucleus Medical Art, Inc.

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:

  • Living or working in crowded group conditions, such as:
    • Nursing home
    • School
    • Military forces
    • Daycare center

All the remaining factors don’t increase the risk of getting flu, but they do increase the risk of developing complications from flu:

  • Age: newborn babies and the elderly
  • Women in the third trimester of pregnancy
  • Diabetes
  • Weakened immune systems, such as in:
  • Chronic lung, heart, kidney, or blood conditions

Symptoms

Influenza symptoms usually start abruptly. They may include:

  • Fever and chills
  • Severe muscle aches
  • Severe fatigue
  • Headache
  • Decreased appetite, other gastrointestinal symptoms like nausea and vomiting
  • Runny nose, nasal congestion
  • Sneezing
  • Watery eyes, conjunctivitis
  • Sore throat
  • Cough
  • 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 (Relenza) and oseltamivir (Tamiflu). Children may be at an increased risk of self-injury and confusion shortly after taking oseltamivir, and should be closely monitored for signs of unusual behavior.

The FDA repeated its warning of possible adverse effects in patients, especially children, taking oseltamivir. In some cases, these effects (eg, hallucinations, delirium, abnormal behavior) resulted in injury and death. * 5

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.

Bed Rest

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.

Saline Nasal Sprays

In a study, researchers concluded that the nasal wash may reduce symptoms, medication use (eg, antipyretics, nasal decongestants, antibiotics), and school absence. * 4

Cough Medicines

These include:

  • Over-the-counter (OTC) cough and cold medicines, including decongestants, expectorants, antihistamines, antitussives (cough suppressants)
    • The Food and Drug Administration (FDA) recommends that OTC cough and cold products should not be used to treat infants or children less than two years old. Rare but serious side effects have been reported, including death, convulsions, rapid heart rates, and decreased levels of consciousness. The FDA is still reviewing data about the safety of these products in children aged 2-11 years, since serious side effects have also been reported in this age group. * 3
  • Prescription cough medicines
  • Cough drops

Prevention

Good preventive measures include:

  • Wash hands thoroughly, including use of alcohol-based gels.
  • Avoid touching eyes or nose prior to washing hands.
  • Avoid biting fingernails.
  • Avoid sharing personal items during the flu season.
  • Consider the flu vaccine .
    • Indications for a yearly flu vaccine, which should be discussed with your doctor:
      • Persons older than 50 years of age
      • Residents and employees of nursing homes and long-term care facilities
      • People with chronic heart and lung conditions
      • People with chronic metabolic disease, kidney problems, hemoglobin abnormalities, or immune system problems
      • Children and teenagers routinely taking aspirin
      • Pregnant women
      • Healthcare providers
      • Household members of high-risk individuals
      • Children age six months to five years
      • Anyone wishing to reduce their risk of getting the flu should consider the vaccine.

The vaccine has been associated with fewer hospitalizations and deaths from influenza or pneumonia among the elderly living in the community. * 2

Two forms of flu vaccine are available—injectable and nasal spray (FluMist). In a study comparing the effectiveness of the two forms in children, researchers found that the nasal spray led to fewer cases of influenza through a single flu season. Talk to your doctor about which vaccine is the most appropriate for you or your child. * 1

RESOURCES:

American Lung Association
http://www.lungusa.org

Centers for Disease Control and Prevention
http://www.cdc.gov/flu

CANADIAN RESOURCES:

Canadian Health Network
http://www.canadian-health-network.ca/

Capital Health
http://www.cdha.nshealth.ca/

References:

American Lung Association website. Available at: http://www.lungusa.org .

CDC MMWR 2006;55(RR10):1-42.

Derlet R, Lawrence R. Influenza. Emedicine website. Available at: http://www.emedecine.com/med/topic1170.htm .

Griffith's 5-Minute Clinical Consult . Lippincott Williams & Wilkins; 1999.

Influenza vaccines. WHO position paper. Wkly Epidemiol Rec . 2002;77:229-240. World Health Organization website. Available at: http://www.who.int/docstore/wer/pdf/2002/wer7728.pdf . Accessed August 30, 2005.

Leblebicioglu H, Brook I. Influenza. Emedicine website. Available at: http://www.emedecine.com .

MMWR Weekly: Recommended immunization schedules for 0-18 years-United States, 2008. Center for Disease Control website. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5701a8.htm . Updated January 11, 2008. Accessed January 24, 2008.

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.

* 1 3/2/2007 DynaMed Systematic Literature Surveillance 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;356:685-696.

* 2 10/15/2007 DynaMed Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance : Nichol KL, Nordin JD, Nelson DB, Mullooly JP, Hak E. Effectiveness of influenza vaccine in the community-dwelling elderly. N Engl J Med. 2007;357:1373-1381.

* 3 1/30/2008 DynaMed Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance : Public health advisory: Nonprescription cough and cold medicine use in children—FDA recommends that over-the-counter (OTC) cough and cold products not be used for infants and children under 2 years of age. US Food and Drug Administration website. Available at: http://www.fda.gov/cder/drug/advisory/cough_cold_2008.htm . Accessed January 30, 3008.

* 4 2/28/2008 DynaMed Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance : Slapak I, Skoupá J, Strnad P, Horník P. Efficacy of isotonic nasal wash (seawater) in the treatment and prevention of rhinitis in children. Arch Otolaryngol Head Neck Surg. 2008;134:67-74.

* 5 3/12/2008 DynaMed Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance : 2008 safety alerts for drugs, biologics, medical devices, and dietary supplements: tamiflu (oseltamivir phosphate). US Food and Drug Administration website. Available at: http://www.fda.gov/medwatch/safety/2008/safety08.htm#Tamiflu . Accessed March 12, 2008.



Last reviewed February 2008 by Jill Landis, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.


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