Information about Influenza

What is influenza?

Influenza is a viral infection that affects mainly the nose, throat, bronchi and, occasionally, lungs. Infection usually lasts for about a week, and is characterized by sudden onset of high fever, aching muscles, headache and severe malaise, non-productive cough, sore throat and rhinitis.

The virus is transmitted easily from person to person via droplets and small particles produced when infected people cough or sneeze. Influenza tends to spread rapidly in seasonal epidemics.

Most infected people recover within one to two weeks without requiring medical treatment. However, in the very young, the elderly, and those with other serious medical conditions, infection can lead to severe complications of the underlying condition, pneumonia and death.

Seasonal influenza occurs every year and the viruses change each year - but many people have some immunity to the circulating virus which helps limit infections. Some countries also use seasonal influenza vaccines to reduce illness and deaths.

Pandemic Influenza A (H1N1) 2009 is a new influenza virus that has never circulated among humans before. After outbreaks in North America early in 2009, the virus spread rapidly around the world. Pandemic influenza is transmitted like seasonal influenza but people have virtually no immunity to it. Mitigating its effects is a public health priority.

What is Pandemic Influenza A (H1N1) 2009?

This is a new influenza A (H1N1) virus that has never before circulated among humans. This virus is not related to previous or current human seasonal influenza viruses. Most people have no or little immunity and, therefore, this virus could cause more infections than are seen with seasonal flu. The World Health Organization (WHO) is working closely with manufacturers to expedite the development of a safe and effective vaccine but it will be some months before it is available.

The new influenza A (H1N1) appears to be as contagious as seasonal influenza, and is spreading fast particularly among young people (from ages 10 to 45). The severity of the disease ranges from very mild symptoms to severe illnesses that can result in death. The majority of people who contract the virus experience the milder disease and recover without antiviral treatment or medical care. Of the more serious cases, more than half of hospitalized people had underlying health conditions or weak immune systems.

What is H5N1 (Avian) Influenza?

Avian influenza ("bird flu") is an infectious disease of birds caused by type A strains of the influenza virus. The infection can cause a wide spectrum of symptoms in birds, ranging from mild illness, which may pass unnoticed, to a rapidly fatal disease that can cause severe epidemics.

Avian influenza viruses do not normally infect humans. However, there have been instances of certain highly pathogenic strains causing severe respiratory disease in humans. In most cases, the people infected had been in close contact with infected poultry or with objects contaminated by their faeces. Nevertheless, there is concern that the virus could mutate to become more easily transmissible between humans, raising the possibility of an influenza pandemic.

How do people become infected with Influenza?

Influenza viruses are found in the nose and throat. Because children touch their noses, eyes and mouths often, put things in their mouths, and touch each other often during play, flu germs spread easily. There is also a lot of contact between parents or caregivers and children: holding hands, picking up, feeding, changing diapers and so on.

The virus is spread from person-to-person. It is transmitted as easily as the normal seasonal flu and can be passed to other people by exposure to infected droplets expelled by coughing or sneezing that can be inhaled, or that can contaminate hands or surfaces.

To prevent spread, people who are ill should cover their mouth and nose when coughing or sneezing, stay home when they are unwell, clean their hands regularly, and keep some distance from healthy people, as much as possible.

There are no known instances of people getting infected by exposure to pigs or other animals. The place of origin of the virus is unknown.

What are the signs and symptoms of infection?

Influenza usually begins with sudden fever, chills and shakes, headache, muscle aches, extreme tiredness, dry cough and sore throat. Loss of appetite is common. People with the flu generally feel very sick and want to stay in bed.

Signs of influenza A (H1N1) are flu-like, including fever, cough, headache, muscle and joint pain, sore throat and runny nose, and sometimes vomiting and diarrhoea.

Although children with the flu may have many of the same symptoms as adults, there are some differences:
» Newborns and infants may have a high fever that can't be explained, and no other signs.
» Young children usually have temperatures over 39.5°C and may have febrile seizures (convulsions).
» Stomach upsets, vomiting, diarrhea and abdominal (stomach) pain are more common in younger children.
» Earaches and red eyes are also more common.
» In some cases, muscle swelling can lead to severe leg or back pain.

Flu is an important cause of the following conditions in young children:
» croup (an infection of the throat and vocal cords),
» pneumonia (lung infection),
» bronchiolitis (infection of the tiny airways that lead to the lungs).

Influenza is more severe in children under 2 years of age and in children with certain chronic conditions.

In rare cases, influenza may affect the brain, causing prolonged seizures, confusion or unresponsiveness. In rare cases, it may affect the heart. Influenza may also weaken the immune system and lead to bacterial infections of the ear, lung or sinuses.

Most healthy people recover from the flu without any serious problems. Fever and muscle aches usually last only 2 to 4 days, but cough and tiredness may go on for 1 to 2 weeks or more.

When should someone seek medical care?

A person should seek medical care if they experience shortness of breath or difficulty breathing, or if a fever continues more than three days. For parents with a young child who is ill, seek medical care if a child has fast or labored breathing, continuing fever or convulsions (seizures).

Contact your doctor or take your child to an emergency department if your child:
» has signs of influenza and has lung or heart disease, has an illness or is taking treatment that affects the immune system, takes acetylsalicylic acid (ASA or Aspirin) regularly for a medical condition or has any other chronic illness requiring regular medical care;
» is less than 3 months old and has a rectal temperature over 38.5°C;
» has trouble breathing when resting, is wheezing, has chest pain when breathing or is coughing up bloody sputum (phlegm or saliva);
» drinks very little fluid and has not urinated at least every 6 hours when awake;
» has vomiting for more than 4 hours, or has severe diarrhea;
» is constantly irritable and will not calm down;
» is listless, not interested in playing with toys or unusually sleepy; or
» still has a fever and is not feeling better after 5 days or was feeling better and suddenly develops a new fever.

Take your child immediately to a hospital emergency department or call 911 if your child:
» has severe trouble breathing or blue lips;
» is limp or unable to move;
» is hard to wake up or does not respond;
» has a stiff neck;
» seems confused; or
» has a seizure (convulsion/fit).

Treating influenza: What parents can do

» Keep your child as comfortable as possible and encourage rest. If he has fever, dress him in lightweight clothing and keep the room temperature around 20°C.

» Offer cool fluids often. Extra fluids are needed to replace those lost in sweat. If your child's urine is darker than usual, she needs to drink more.

» Your child may not want to eat. Offer small, nutritious meals.

» Monitor your child's temperature. For pain relief, muscle aches or fever with temperature higher than 38.5°C, use acetaminophen (eg, Tylenol, Tempra and Panadol). Ibuprofen (eg, Advil and Motrin) may be used for children over 6 months old. Use the dose and schedule recommended on the package or by your doctor or pharmacist. Do not give acetylsalicylic acid (ASA [eg, Aspirin]) or any cold medicine with it, to children or teenagers with influenza because it can lead to brain and liver damage (Reye syndrome).

» Over-the-counter cough and cold medicines (which don't need a doctor's prescription) should not be given to children younger than 6 years of age unless prescribed by your doctor. Ask your doctor or pharmacist before giving over-the-counter medicines to a child under 12 years of age or anyone who is taking other medicines or has a chronic illness. Read label instructions carefully and do not take more than recommended.

» Coughing helps to clear mucus from the chest. For an older child with a frequent, dry cough that prevents sleeping, a product with dextromethorphan may help, but studies have shown that these products don't have much benefit. Decongestants and antihistamines won't stop coughing.

» If an infant is having trouble feeding because of a stuffed nose, use a rubber suction bulb to clear the mucus. Use saline nose drops or saline nose spray if the mucus is very thick. The spray goes well into the nasal passages and may be more effective than the drops.

» A cool mist humidifier will make a child with a stuffed nose more comfortable. Clean and dry the humidifier thoroughly to prevent bacterial or mould contamination. Hot water vaporizers are not recommended because of the risk of burns.

» Medicated nose drops or sprays provide only brief relief and should not be used for more than 2 to 3 days because nasal congestion can actually get worse. These should not be used in children under 6 years of age. Decongestants taken by mouth are not very effective and can cause rapid heartbeat or insomnia in children. Antihistamines are not effective for influenza.

» Influenza cannot be treated with antibiotics. Antibiotics should be used only when children develop bacterial complications, such as ear infection or pneumonia.

» Gargling with warm water will ease a sore throat.

For children 3 years or older, sucking on sugarless hard candy or lozenges containing honey, herbs or pectin also helps. Throat lozenges containing medications that numb the throat (dyclonine, benzocaine, hexylresorcinol, menthol and phenol) should not be used by young children because these may affect their ability to swallow.

If your child has lung or heart disease, an illness that affects the immune system or some other chronic condition that requires regular medical attention and you think that the child may have influenza, call your doctor right away. Your doctor may prescribe an antiviral drug. Amantadine (Symmetrel), oseltamivir (Tamiflu) and zanamivir (Relenza) are antiviral medications that can fight influenza viruses. These drugs may also be prescribed for healthy persons with severe influenza. They must be taken within 48 h of the first symptoms to be effective.

Supportive care at home - resting, drinking plenty of fluids and using a pain reliever for aches - is adequate for recovery in most cases. (A non-aspirin pain reliever should be used by children and young adults because of the risk of Reye's syndrome.)

Preventing influenza through immunization

Influenza can be prevented through immunization. Most people who are vaccinated will not get influenza. People who do get it will have a less serious case. Because new influenza strains turn up yearly, you have to get the vaccine every year. The influenza vaccine only prevents influenza. It does not prevent infections with other respiratory viruses that people sometimes call the 'flu'. The flu shot cannot cause the flu.

The influenza vaccine ('flu shot') is available in the fall and provides protection for the influenza season (November to April). The vaccine takes about 2 weeks from the time it is given to provide full protection. Children younger than 9 years old need 2 shots (4 weeks apart) the first year they are immunized. The current influenza vaccine does not work in children younger than 6 months old.

The Canadian Paediatric Society recommends that all children 6 months to 23 months old, as well as older children with certain chronic conditions, get a flu shot each year. Parents, older siblings, others living in the home and caregivers of children younger than 2 years of age should also receive the vaccine to prevent them from getting the infection and passing it on to younger children. Note: babies under 6 months old cannot get the vaccine, as it does not work in this age group.

Make sure your child has also received all of the other recommended vaccines. These will help prevent some of the complications of the flu, such as bacterial infections of the ears or lungs.

Preventing influenza for Parents & Caregivers

» Handwashing is the most important way to reduce the spread of flu.
» Wash your hands after being in direct contact with someone who has a respiratory infection.
» Wash your own hands and your child's hands after wiping your child's nose.
» Wash your hands after coughing, sneezing or wiping your nose.
» When water and soap are not available, use premoistened hand wipes or alcohol-based hand rinses.
Keep hand rinses out of reach of children because they may be harmful if swallowed.
» Wash your hands after touching objects handled by someone who has influenza.
» Teach children to cover their noses and mouths with tissues when sneezing or coughing, to put used tissue in a wastebasket immediately, and to wash their hands after wiping their nose or handling tissues.
» If a family member has the flu, clean surfaces (such as toys, bathroom taps, doorknobs) after the ill person has touched them.
» If your child attends daycare, tell the caregiver if you think your child has influenza.
» Keep your child at home, away from daycare or school, until the fever is gone and she is feeling better.
» When both parents work outside the home, plan ahead by making arrangements for when your child becomes ill.