Influenza Causes and Risks

What Causes the Flu?

The flu is caused by varying strains of the flu virus. The flu is divided into 3 major types (A, B, and C) with each of these types being further divided into differing strains. Influenza A infects mostly humans and birds, though it also affects pigs. Prolonged and close interaction between humans and birds, such as chickens, allow for the virus to mutate and jump from species to species. This is why the bulk of influenza A virus begin in Southeast Asia. Commonly-known strains of influenza A are the Spanish Flu, the Bird Flu, and the Swine Flu. Because influenza A mutates quickly, a seasonal flu shot is recommended every year. It also explains why vaccines do not offer protection from year to year.

Influenza B infects mainly humans. This type is less common that influenza A. Because it does not mutate as quickly as influenza A, it is typically not to blame for the yearly need for a flu vaccine. Influenza C is even more rare and typically results in only a mild case of the flu.

The flu is very contagious and easily spread because it inhabits droplets of mucus in the lungs. Whenever an infected person coughs or sneezes, these infected droplets are spread throughout the air and contaminate whatever surface they land on. Other bodily fluids carry the virus as well, such as saliva. Be especially aware of sensitive parts of the body: the eyes, the nose, and the mouth. These are the most common sites where flu infection occurs. Breathing contaminated air or touching a contaminated surface and then touching one of these parts of the body is usually how persons are infected with the flu virus. Being mindful of touching your eyes, nose, and mouth and repeated washing of hands are some of the best prevention methods of avoiding contamination.

The flu vaccination is also especially helpful in preventing infection. A new flu vaccine is released to doctor's offices and pharmacies every fall, the traditional beginning of the flu season. Unlike other vaccines, resistance is not maintained year to year. A new round of vaccinations is necessary due to mutations in the flu strains. Children and the elderly are especially vulnerable to the flu and are among the sections of the population most encouraged to be vaccinated.

Last Updated: October 17, 2016