Definition

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

The Upper Respiratory Tract

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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:
    • Cancer patients
    • AIDS patients
    • People taking immunosuppressive drugs
    • People who have had their spleen removed
  • 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 and oseltamivir. 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.

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.

Cough Medicines

These include:

  • Over-the-counter cough medicines (including suppressants and expectorants)
  • 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 6-59 months of age
      • Anyone wishing to reduce their risk of getting the flu should consider the vaccine.

Influenza vaccine has been associated with fewer hospitalizations and deaths from influenza or pneumonia among the elderly living in the community. Researchers who followed a large group of adults older than 65 during the ten flu seasons from 1990-2000 found that those who received the influenza vaccine were less likely to be hospitalized and had a lower mortality rate than those who did not receive the vaccine.*

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. *