It’s that dreaded time of year. One minute, you’re fine; the next, you’re struck down with a high fever, achy joints, headache and a vicious cough. Fuelling anxiety this year is talk of a pandemic, as outbreaks of avian flu in parts of Asia have led to the deaths of approximately 70 people.

Yet, this flu season, an estimated three million to eight million Canadians will become infected with the influenza virus, leading to respiratory illnesses that typically last for a week to 10 days.

The flu virus spreads through droplets that have been coughed or sneezed into the air by someone who is infected. Once the virus enters the body — via the eyes, nose or mouth — it attaches itself to the lining of the airways and quickly replicates. The flu symptoms are the body’s way of trying to ward off the foreign virus.

What makes the flu virus unique is its ability to change year-over-year. This phenomenon is what experts call the “drift and shift” process. The flu virus’s genetic machinery is constantly mutating or “drifting,” resulting in small changes in its genetic composition. Sometimes the virus swaps major genetic elements with other viruses, resulting in a major “shift” in its makeup. The result is a strain of the flu virus that researchers have never seen before.

In an effort to keep up with the flu’s constant evolution, the World Health Organization gathers data from laboratories around the world to determine which flu strains are circulating. With this information, it develops a vaccine that best matches the viruses it believes will be around in the upcoming flu season. In Canada, the flu vaccine consists of three strains of killed viruses — this year, they are H1N1, H3N2 and B Shanghai — that cause the body to generate antibodies to fight off infection.

Although the flu virus has been around as long as people, misconceptions still abound. Herewith is a debunking of the myths:

myth: You can catch the flu from the flu shot.

fact: The flu vaccine consists of killed viruses and, therefore, cannot cause the flu.

So why do people often feel rundown after the shot? “Unfortunately, at the same time that people are getting the flu vaccine, there are other viruses floating around with which they may become infected,” says Dr. Theresa Tam, associate director of immunization and respiratory infections at the Public Health Agency of Canada in Ottawa.

As well, it takes two weeks for the vaccination to take full effect, which means you can still become infected within a couple days of receiving the shot.

myth: The flu causes nausea, vomiting and diarrhea.

fact: There is no such thing as the “stomach flu.”

“One of the common misconceptions among people suffering from stomach pain is that they are suffering from ‘stomach flu’ — which has nothing to do with the influenza virus,” Tam says. People who have symptoms of nausea and diarrhea are probably infected with one of several viruses such as the norovirus, which attacks the gastrointestinal system and results in a condition called gastroenteritis. The influenza virus attacks only the respiratory system.

Children sick with the flu for the first time may experience nausea, vomiting and diarrhea, she adds, but these symptoms are extremely rare in adults. “It’s probably a result of being exposed to the virus for the first time,” Tam says.

myth: The flu is simply a more serious form of the common cold.

fact: The flu and the common cold are caused by completely different viruses.

Although both flu and common cold viruses attack the respiratory tract, a cold is the result of one of several different viruses, and typically results in a shorter, less severe illness. The flu, by contrast, is caused only by the influenza virus and can develop into more serious illnesses, such as pneumonia and respiratory failure.

“While the cold and the flu have similar symptoms, the flu typically lasts much longer [a week to 10 days, compared with two to three days for a cold] and is accompanied by a fever, severe headache and extreme fatigue,” says Dr. Judy MacDonald, deputy officer of health for the Calgary Health Region. Another difference is the way in which the viruses attack the body, she says.

@page_break@Cold sufferers typically feel the onset of symptoms a day or so before the cold reaches its peak, whereas the flu strikes much more quickly. “You feel instant fatigue with the flu,” she says.

myth: The avian flu, or “bird flu,” is a serious threat to Canadians.

fact: The avian flu virus (H5N1) hasn’t yet been detected in Canada, and there is no evidence to suggest that it can be transmitted from person to person.

Still, researchers warn, a radical change or “shift” in the current H5N1 virus could mean that it will become a pandemic in the future. “With all of the infection in birds still spreading [in parts of Asia], the chances of transmission to humans increase, and the chances of getting rid of it become more remote,” MacDonald says.

And the constant mutating of the virus only complicates matters. “We really can’t prepare a vaccine ahead of time because there is no way of knowing what that virus is going to look like,” MacDonald says. What is more, it takes months to develop an effective vaccination.

Although there is no way to tell if or when the avian flu will become a pandemic, people can prepare themselves by developing good habits, she says: “Washing their hands and using tissues when they cough and sneeze are simple things people can do to make themselves better prepared should the avian flu reach Canada.” IE