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Influenza (Flu)

Basic Information

Influenza or flu is an acute respiratory tract infection that is caused by a virus and is highly contagious. It has caused worldwide epidemics during the last 400 years, one of the most severe being the flu epidemic of 1918-1919 that caused 21 million deaths worldwide. Fortunately there is now a vaccine for flu that certainly lessens mortality in groups that are considered high risk. Every winter in temperate climates outbreaks of flu occur, varying in severity. Influenza A is the virus most frequently seen though there is a virus B and C as well and they can mutate into different forms.

Flu is spread by contact with individuals who are infected with the virus -- in other words it is spread person-to-person -- either airborne (small-particle aerosols deposited on the respiratory tract) passed by a sneeze or cough or it may contaminate articles with the virus so that flu is spread indirectly, say, via a drinking glass. During sporadic outbreaks each winter people in closed environments or in crowded places are at risk for coming into contact with the virus. And if you are rundown from stress or fatigue you are at greater risk for picking it up. Acute outbreaks are thought to occur every three years.

In most cases spontaneous recovery occurs within 1 to 2 weeks, usually without complications. But in some patients complications may occur and recovery may take up to 6 weeks. Complications most commonly seen are bronchial infections and pneumonia and in most healthy individuals treatment with antibiotics will restore the patient's health. But in certain high risk groups, complications may prove severe and even deadly. That is why a yearly flu shot is recommended for high risk groups.

Who comprises these high risk groups or who is the flu vaccine especially recommended for?

  • persons with HIV or who are otherwise immunocompromised
  • persons over 65
  • patients with pulmonary or cardiac disease
  • residents of nursing homes
  • patients with chronic illness
  • health care providers
  • children on chronic aspirin therapy
  • pregnant women whose 3rd trimester occurs during winter

Anyone who would like a flu shot may have one (unless it is contraindicated by your health care provider) but it is especially recommended annually for the above-listed group (again, unless contraindicated by your health care provider). The flu vaccine is an inactivated virus vaccine and should be given around October for maximum effectiveness during the flu season which lasts from November through March. The vaccine protects against several specific strains of influenza A.

The antiviral drug amantadine can be used as a prophylaxis against influenza for those who failed to be vaccinated or for those household members of a patient with the flu. It helps reduce fever as well as respiratory symptoms if given early enough.

The flu has a 48 hour incubation period.

Symptoms

Usually the onset is sudden.

Chills and fever up to 102 degrees or 103 degrees usually develops within 24 hours. Headache is an early symptom along with mild respiratory ailments such as a scratchy throat. Later, the respiratory ailments increase with a cough and become severe.

Other symptoms can include:

  • muscle aches
  • fatigue
  • runny nose
  • vomiting and nausea (most usually in children)

Diagnosis/Treatment

Flu is diagnosed in a clinical setting by your health care provider who will evaluate your symptoms with knowledge of whether local epidemics are in the area. A diagnostic test, if there is any question, can isolate the virus by nasal or throat swab.

In uncomplicated cases the flu resolves within 1 or 2 weeks but if complications arise you should contact your health care provider promptly in case antibiotics or other treatment is needed.

Signs to watch out for that may mean your condition is worsening include:

  • increased fever
  • chest pain
  • shortness of breath
  • neck stiffness
  • blood in the sputum
  • worsening cough
  • earache

You must rest when you have the flu as well as several days following cessation of your symptoms, especially fever. Drink plenty of liquids such as fruit juices, tea and drinks that are not carbonated. This is especially important if you have a high fever. Watch for signs of dehydration. Ask your health care provider if you should take aspirin -- it is contraindicated for certain persons, especially children, because of a link with Rey's syndrome (encephalitis).

You may:

  • use cough syrups
  • use nasal decongestants
  • use acetaminophen
  • gargle with warm or cold water or salt water
  • use a humidifier to keep air moist

Be thoughtful by trying not to spread germs to others. Wash your hands before handling food and after blowing your nose. Keep away from anyone whom you know is HIV positive. Conversely if you are HIV positive stay away from any patient with the flu.

Call your health care provider if symptoms worsen as described above.