Infectious Diseases
Influenza (Flu)
Influenza (or flu) is a highly contagious viral infection and is one of the most severe illnesses of the winter season. An estimated 5 to 20 percent of the population in the US contract influenza each year.
Influenza is a viral infection of the upper respiratory system, which includes the nose, bronchial tubes, and lungs. Influenza is characterized by the following:
- fever
- muscle aches
- sore throat
- headache
- nonproductive cough
Influenza can make people of any age ill. Although most people and children are ill with influenza for 4-10 days, some have a much more serious illness and may need to be hospitalized. Influenza may also lead to pneumonia and rarely to death. Severe illness and death is most often seen in the elderly or in patients with underlying chronic medical conditions.
Influenza viruses are divided into three types designated as A, B and C.
- Influenza types A and B are responsible for epidemics of respiratory illness that occur almost every winter and are often associated with increased rates of hospitalization and death. Efforts to control the impact of influenza are focused on types A and B. One of the reasons the flu remains a problem is because the viruses actually alter their genes, exposing adults and children to slightly different viruses each year.
- Influenza type C usually causes either a very mild respiratory illness or no symptoms at all. It does not cause epidemics and does not have the severe public health impact that influenza types A and B do.
Influenza viruses continually mutate or change, which enables the virus to evade the immune system of a child. People are susceptible to influenza infection throughout their lives. The process works as follows:
- A person infected with influenza virus develops antibody against that virus.
- The virus mutates or changes.
- The "older" antibody no longer recognizes the "newer" virus.
- Reinfection occurs.
The older antibody can, however, provide partial protection against reinfection; it can also make disease caused by the new virus less severe. Currently, three different influenza viruses circulate worldwide: two type A viruses and one type B virus. Immunizations given each year to protect against the flu contain the influenza virus strain from each type that is expected to cause the flu within that year.
An influenza virus is generally passed from person to person by airborne transmission. This means your child can contract the flu by coming in contact with airborne viruses from an affected person by way of sneezing or coughing. The virus can also live for a short time on objects such as doorknobs, pens/pencils, keyboards, telephone receivers, and eating or drinking utensils, for example. Therefore, it may also be spread when your child touches something that has been handled by someone infected with the virus and then your child touches his/her own mouth, nose, or eyes.
People are generally the most contagious with the flu 24 hours before they start having symptoms and during the time they have the most symptoms. Children may continue to spread the virus for days after they are feeling better. That is why it is hard to prevent the spread of the flu, especially among children, because they do not always know they are sick while they are still spreading the disease. The risk of infecting others usually stops around the seventh day of the infection.
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 or clear nasal discharge
- worsening cough
- 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.
A cold and the flu (influenza) are two different illnesses. A cold is relatively harmless and usually clears up by itself after a period of time, although sometimes it may lead to a secondary infection, such as an ear infection. However, the flu can lead to complications, such as pneumonia and even death. What may seem like a cold, could, in fact, be the flu. Be aware of these differences:
A new influenza vaccine is introduced each September. It is usually recommended for specific groups of people (see below), as well as for persons who want to avoid having the flu. In addition, two antiviral medications (Zanamivir and Oseltamivir) are approved for use in preventing the flu in children. All of these medications are available by prescription, and a physician should be consulted before any medication is used for preventing the flu.
A nasal-spray flu vaccine, called FluMist, is currently approved to prevent flu due to influenza A and B viruses in healthy children and adolescents (ages two to 17), and healthy adults (ages 18 to 49). As with other live virus vaccines, FluMist should not be given for any reason to pregnant women and people with immune suppression, including those with immune deficiency diseases, such as AIDS or cancer, and people who are being treated with medications that cause immunosuppression.
Vaccine effectiveness varies from year to year, depending upon the degree of similarity between the influenza virus strains included in the vaccine and the strain or strains that circulate during the influenza season begins. Vaccine strains must be chosen nine to ten months before the influenza season. Sometimes, changes occur in the circulating strains of viruses between the time the vaccine actually reaches the community. These changes may reduce the ability of the vaccine-induced-antibody to inhibit the newly mutated virus, thereby decreasing the chance that the vaccine will work.
Vaccine effectiveness also varies from one person to another, depending on factors such as age and overall health.
The most serious side effect that can occur after influenza vaccination is an allergic reaction in people who have a severe allergy to eggs. For this reason, children who have an allergy to eggs should not receive the influenza vaccine. According to the National Center for Infectious Diseases of the Centers for Disease Control and Prevention (CDC), influenza vaccine causes no side effects in most children who are not allergic to eggs.
Less than one-third of people who receive the vaccine experience some soreness at the vaccination site, and about 5 to 10 percent experience mild side effects, such as a headache or a low-grade fever for about a day after vaccination. Because these mild side effects mimic some influenza symptoms, some people believe influenza vaccine causes them to get influenza. However, the injectable vaccine is a dead virus that does not and cannot cause the flu. The nasal spray vaccine (LAIV) causes some people to have a mild runny nose or sore throat for a couple of days, but otherwise has no side effects. As eggs are used in the manufacture of this vaccine as well, those with egg allergy are at the same risk from the nasal spray vaccine as they are from the injectable vaccine. The nasal spray vaccine also should not be given to patients who have moderate to severe asthma or those on chronic aspirin therapy.
Pediatric experts strongly recommend an annual flu vaccination for children.
The Centers for Disease Control (CDC) recommends that healthy children aged 6 months up to their 19th birthday, their close contacts (people who live with them, and out-of-the home caregivers such as nannies, daycare providers, etc.) should get a flu vaccine.
Vaccination is especially important for any child aged 6 months and older with chronic health problems including:
- asthma or other lung problems
- immune suppression
- chronic kidney disease
- heart disease
- HIV/AIDS
- diabetes
- sickle cell anemia
- long-term aspirin therapy
- any condition that can compromise respiratory function
Children under 6 months old are the pediatric group at highest risk of influenza complications, but they are too young to get a flu vaccine. The best way to protect young children is to make sure members of their household and caregivers get vaccinated.
Contrary to popular believe, vaccine effectiveness does not change over a course of months; therefore, it is ok to get flu vaccine as soon as it is available, even in late August or early September.
In the United States; two vaccines are available:
- The “flu shot” – an inactivated vaccine (containing killed virus) that is given with a needle, usually in the arm. The flu shot is approved for use in people older than 6 months, including healthy people and people with chronic medical conditions.
- The nasal-spray flu vaccine – a vaccine made with live, weakened flu viruses that do not cause the flu (sometimes called LAIV for “live attenuated influenza vaccine”). LAIV is approved for use in healthy people 2 to 49 years of age who are not pregnant.
Please call your child's pediatrician early about scheduling your child's flu shot.
Specific treatment for influenza will be determined by your child's physician based on:
- your child's age, overall health, and medical history
- extent of the condition
- your child's tolerance for specific medications, procedures, or therapies
- expectations for the course of the condition
- your opinion or preference
The goal of treatment for influenza is to help prevent or decrease the severity of symptoms. There is no cure for influenza; it runs its course and resolves. Treatment may include:
- medications to relieve aches and fever (Aspirin should not be given to children with a fever without first consulting your child's physician.). The drug of choice for children would be acetaminophen (Tylenol).
- medications used for congestion and nasal discharge
- bed rest
- increased fluid intake
- medication for your child's cough may be prescribed by your child's physician after a thorough evaluation
- antiviral medications - the medications may help to shorten the duration of the illness and to decrease the severity of the flu, but do not cure the flu. They must be started very shortly after symptoms begin. Two types of these medications are Zanamivir and Oseltamivir. The length of therapy will be determined by your child's physician.
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Disclaimer:
This information is not intended to substitute or replace the professional medical advice you receive from your child's physician. The content provided on this page is for informational purposes only, and was not designed to diagnose or treat a health problem or disease. Please consult your child's physician with any questions or concerns you may have regarding a medical condition.
Last reviewed on 9/12/2008