Influenza
Introduction
Influenza is a viral infection that attacks the respiratory system, including your nose, throat, bronchial tubes and lungs. Although it's commonly called the flu, influenza is not the same as the stomach virus that causes diarrhea and vomiting.
Millions of people, including 500,000 Americans, died in the 1918 influenza pandemic. Today, according to the Centers for Disease Control and Prevention, as many as 36,000 Americans die each year of complications of influenza and more than 200,000 are hospitalized.
Anyone can get the flu, but young children, older adults, people with weakened immune systems and those with chronic illnesses are especially vulnerable. If you're at high risk of flu, your first line of defense is an annual flu shot. Although the shot doesn't offer 100 percent protection, it can reduce your chance of infection and help prevent serious complications if you do get sick.
Signs and symptoms
Initially, the flu may seem like a common cold, with a runny nose, sneezing and sore throat. But colds usually develop slowly, whereas the flu tends to come on suddenly. And although a cold can be a nuisance, you usually feel much worse with the flu.
Common signs and symptoms of the flu include:
- Fever over 101 F. Children with the flu tend to have higher fevers than adults have — often as high as 103 to 105 F.
- Chills and sweats.
- Headache.
- Dry cough.
- Muscular aches and pains, especially in your back, arms and legs.
- Fatigue and weakness.
- Nasal congestion.
- Loss of appetite.
- Diarrhea and vomiting. Although children may have these signs, diarrhea and vomiting are rare in adults.
Causes
Flu viruses travel through the air in droplets when someone with the infection coughs, sneezes or talks. You can inhale the droplets directly, or you can pick up the germs from an object such as a telephone or computer keyboard and then transfer them to your eyes, nose or mouth.
The flu is caused by three types (strains) of viruses — influenza A, B and C. Type A is responsible for the deadly influenza pandemics (worldwide epidemics) that strike every 10 to 40 years. Type B can lead to smaller, more localized outbreaks that generally occur every three to 15 years. And either types A or B can cause the flu that circulates almost every winter. Type C is less common and causes only mild symptoms.
Type C is a fairly stable virus, but types A and B are constantly changing, with new strains appearing regularly. Once you've had the flu, you develop antibodies to the virus that caused it, but those antibodies won't protect you from new strains. That's why doctors recommend getting a flu shot every year.
Treatment
Most often, you'll need nothing more than bed rest and plenty of fluids to treat the flu. But in some cases, your doctor may prescribe an antiviral medication such as oseltamivir (Tamiflu) or zanamivir (Relenza).
These drugs, which treat both influenza A and B, work by deactivating an enzyme the virus needs to grow and spread. If taken soon after you notice symptoms, they may shorten your illness by a day or so. Oseltamivir is an oral medication, but zanamivir is inhaled through a device similar to an asthma inhaler and shouldn't be used by anyone with respiratory conditions such as asthma and lung disease.
Both medications can cause side effects, including lightheadedness, nausea, loss of appetite and trouble breathing. They can also lead to the development of antiviral-resistant viruses.
In November 2006, The Food and Drug Administration (FDA) required the maker of Tamiflu to include a warning that people with the flu, particularly children, may be at increased risk of self-injury and confusion after taking Tamiflu. The FDA recommends that individuals with the flu who take Tamiflu be closely monitored for signs of unusual behavior. Discuss possible side effects with your doctor before starting any antiviral medication.
Prevention
These steps can help you stay healthy, even at the height of flu season:
- Get an annual flu vaccination. The best time to be vaccinated is October or November. This allows your body time to develop antibodies to the flu virus before peak flu season, which in the Northern Hemisphere is usually December through March. Keep in mind that the flu vaccine doesn't offer complete protection, especially for older adults, but it can reduce the risk of illness. In any given year, the flu shot (Fluzone) may be 70 percent to 90 percent effective in young, otherwise healthy people but far less effective in older adults. Health experts still recommend vaccinations for people over 65 because the flu shot may reduce the risk of flu-related complications, hospitalizations and deaths.
Healthy people ages 5 to 49 alternatively may receive the flu vaccine through a nasal spray called FluMist. It protects against the same strains of influenza that the flu shot does. Like the flu shot, FluMist is given every year. Because FluMist contains live but weakened flu viruses, it shouldn't be used by pregnant women, people with weakened immune systems and those with chronic illnesses. A study published in 2006 found that FluMist was only between 30 percent and 57 percent effective in preventing the flu in adults. However, another study in 2006 found that giving nasal spray vaccine to school-age children helped to reduce the spread of flu in the community. And in 2007, researchers compared the effectiveness of FluMist against the flu shot in children ages 6 months to 5 years. The children treated with FluMist experienced about half as many cases of flu as did those treated with the shot. However, Flu Mist increases the risk of wheezing in this age group — especially in children who are 6 to 11 months old — and is not yet FDA approved for children younger than 5 years. Consult with your doctor about which form of vaccination may be best for you or your child.
You can get the flu vaccine from your doctor, at public health centers and many pharmacies. In some areas, flu vaccines are also available at senior or community centers and at supermarkets. - Wash your hands. Thorough and frequent handwashing is the best way to prevent many common infections. Scrub your hands vigorously for at least 15 seconds, rinse well and turn off the faucet with a paper towel. Or use an alcohol-based hand gel containing at least 60 percent alcohol. Hand gels are easy to use and may be even more effective at killing germs than soap and water are.
- Eat right, sleep tight. A poor diet and poor sleep both lower your immunity and make you more vulnerable to infections. A balanced diet that emphasizes fresh fruits and vegetables, whole grains, and small amounts of lean protein works best for most people. On the other hand, the amount of sleep needed for a healthy immune system varies from person to person. In general, adults seem to do best on seven to eight hours of sleep a night. Older children and teens need more rest — between nine and 10 hours every night.
- Exercise regularly. Regular cardiovascular exercise — walking, biking, aerobics — boosts your immune system. Exercise won't prevent every infection, but if you do come down with the flu, you may have less-severe symptoms and recover more quickly than do people who aren't as fit.
- Limit air travel. Researchers say that the pronounced drop in air travel that occurred in the fall of 2001 slowed the spread of the flu and delayed the start of flu season by several weeks. Ordinarily, new flu strains spread rapidly in November, during the height of the holiday travel season, so you may be able to reduce your risk by limiting your time in the air in the late fall.
- Avoid crowds during flu season. Flu spreads easily wherever people congregate — in child care centers, schools, large office buildings, auditoriums, even cruise ships. By avoiding crowds whenever possible during peak flu season, you reduce your chances of infection.
Informations obtained from National Institute of Health.