Influenza (Flu) - Influenza Vaccine

Also called the grippe or the flu, influenza is an acute, highly contagious infection of the respiratory tract.

Although it affects all age-groups, the highest incidence occurs in school-age children. The greatest severity is in young children, elderly people, and those with chronic diseases. In these groups, influenza may even lead to death.

Influenza occurs sporadically or in epidemics (usually during the colder months). Epidemics usually peak within 2 to 3 weeks after initial cases and last 2 to 3 months.

If you're at high risk of getting the flu, your first line of defense is an annual flu vaccine. And if you get the flu, self-care measures can make you more comfortable.

Causes

Influenza results from three types of virus. Type A, the most prevalent, strikes every year, with new serotypes causing epidemics every 3 years. Type B also strikes annually but only causes epidemics every 4 to 6 years. Type C is endemic and causes only sporadic cases.

The infection is transmitted by inhaling a respiratory droplet from an infected person or by indirect contact, such as drinking from a contaminated glass. The virus then invades the epithelium of the respiratory tract, causing inflammation and desquamation.

One remarkable feature of the influenza virus is its capacity for antigenic variation - that is, its ability to mutate into different strains so that no immunologic resistance is present in those at risk. Antigenic variation is characterized as antigenic drift (minor changes that occur yearly or every few years) and antigenic shift (major changes that lead to pandemics).

Signs and symptoms

The following are the most common symptoms of the flu. However, each child may experience symptoms differently.

Influenza is called a respiratory disease, but the whole body seems to suffer when a child has it. Children usually become suddenly ill with any, or all, of the following symptoms:

• fever, which may be as high as 103° F to 105° F
• aches and pains
• not feeling well "all over"
• headache
• cough that is nonproductive
• sore throat
• stuffy nose
• nausea
• vomiting
• diarrhea
• fatigue

Most people recover from influenza within a week, but may be left feeling exhausted for as long as three to four weeks.

The symptoms of influenza may resemble other conditions or medical problems. Always consult your child's physician for a diagnosis.

Diagnostic tests 

At the beginning of an influenza epidemic, many patients are misdiagnosed with other respiratory disorders. Because signs and symptoms of influenza aren't pathognomonic, isolation of the influenza virus through inoculation of chicken embryos (with nasal secretions from infected patients) is essential at the first sign of an epidemic. In addition, nose and throat cultures and increased serum antibody titers help confirm the diagnosis.

Treatment

The patient with uncomplicated influenza needs bed rest, adequate fluid intake, acetaminophen or aspirin to relieve fever and muscle pain (children should only receive acetaminophen), and guaifenesin or another expectorant to relieve nonproductive coughing. Prophylactic antibiotics aren't recommended; they have no effect on the influenza virus.

The antiviral agent amantadine has effectively reduced the duration of influenza A infection. In influenza complicated by pneumonia, the patient needs supportive care (fluid and electrolyte replacements, oxygen, and assisted ventilation) and treatment of bacterial super infection with appropriate antibiotics. No specific therapy exists for cardiac, central nervous system, or other complications.

Prevention

Although there's no guaranteed way - including the vaccine - to prevent anyone from getting the flu, the most simple step you can take is to avoid large crowds. Since it's often nearly impossible to keep kids cooped up, here are some other things you and your family can do to help prevent the spread of infections like the flu:

• Wash your hands thoroughly and frequently.
• Never pick up used tissues.
• Never share cups and eating utensils until you're better.
• Stay home from work or school when you're sick with the flu.
• Cover your mouth and nose with a tissue when you cough or sneeze.