Seasonal influenza (flu) is a common infection of the airways and lungs that can spread easily among humans. In Canada, flu season usually runs from November to April.
Most people recover from the flu in about a week. However, influenza may be associated with serious complications such as pneumonia, especially in infants, the elderly and those with underlying medical conditions like diabetes, anemia, cancer, immune suppression, HIV and kidney disease. On average, the flu and its complications send about 20,000 Canadians to hospital every year, and between 2,000 and 8,000 Canadians die.
The influenza virus spreads by respiratory droplets spread by infected persons through coughing, sneezing or talking. It is also spread through direct contact with objects contaminated by the influenza virus, such as toys, eating utensils, and unwashed hands.
Influenza usually starts with the sudden onset of a headache, sore throat and muscle aches. The onset is often abrupt enough that people can remember precisely when it started. Most people recover from the flu in about a week.
The flu is not a cold. A cold is a mild infection of the upper respiratory passages caused by a variety of viruses. It may last for a week and symptoms include a runny nose, stuffy nose, cough and sore throat. A cold is caused by a rhinovirus, which is much different from an influenza virus. Symptoms such as headache, fever, muscle aches, and nausea do not usually accompany a cold.