Cause
There are three types of influenza virus: Type A is usually responsible for large epidemics and is constantly changing with new strains appearing. Type B causes smaller, more localized outbreaks. Type C is less common and usually causes mild illness. Flu epidemics usually occur between November and March.
Symptoms
Flu symptoms may be similar to those of the common cold, but they tend to develop quickly and are more severe. They can include fever (often sudden and high), chills, headache, muscle aches, dizziness, loss of appetite, cough, sore throat, runny nose, nausea, and weakness.
How It Spreads
Flu spreads by virusinfected droplets coughed or sneezed into the air.
Incubation Period
Symptoms usually appear one to four days after exposure to the virus.
How Long Symptoms Last
Fever and most other symptoms subside within 5 days, but cough and weakness may persist. All symptoms are usually gone within 7 to 14 days.
When to Call Your Child’s Doctor
Children with mild cases usually don’t need to see their doctor. Do call your child’s doctor if your child has a fever of 103 degrees Fahrenheit or higher, if your child—especially your infant younger than three months—has a cough that does not get better over a three- to four-day period, or if your child is having difficulty breathing. A persistent cough, fever, increased breathing rate, or respiratory difficulty may indicate that your child has developed pneumonia as a complication of the flu.
How the Diagnosis Is Made
The doctor will examine your child and listen to the lungs to determine whether any complications have developed, such as pneumonia. If pneumonia is suspected, a chest X-ray may be ordered.
Treatment
Because the flu is caused by a virus, it is not treated with antibiotics unless there is a secondary bacterial infection. Some children with chronic medical conditions may require hospitalization. For a very ill child or one with other conditions that may predispose him to complications, a doctor may prescribe an antiviral medication to relieve symptoms; the medicine must be given within 48 hours of the onset of symptoms.
Home Treatment
Children should rest in bed or play quietly. Give a nonaspirin medication such as acetaminophen (Tylenol) to relieve fever and aches. Do not give aspirin because it is associated with Reye syndrome, a rare but potentially fatal disease, especially if given to a child with influenza or chicken pox.
Prevention
Try to keep your child away from crowds during an epidemic. Make sure that your child washes his hands thoroughly and doesn’t pick up used tissues. The flu vaccine is not routinely recommended for children, except those with chronic heart or lung diseases (including asthma), sickle-cell anemia, diabetes, HIV, or other chronic conditions.
Contagious Periods
The contagious period lasts from the day before to seven days after symptoms appear.
Complications
Pneumonia (infection and inflammation of the lung), caused by the virus and/or a secondary bacterial infection, and otitis media (middle ear infection) are the most common complications. Myocarditis (an infection of the heart) and Reye syndrome are rare complications.