Influenza, better known as flu, is an infectious disease of the lungs and upper airways caused by viruses that can affect both birds and mammals. There are three types of influenza--A, B and C. Though each variant may differ in its symptoms and possible outcomes, they all share common means of spreading.
How the Flu Virus Is Spread
The flu virus is primarily transmitted through bodily fluids such as saliva, feces, blood and mucous. Any contact with these substances could possibly transmit the infection. Therefore, drinking after someone who has the flu, kissing, eating from the same plate or even shaking hands could spread the disease.
But the most common method of flu transmission is through inhalation. When an infected mammal coughs or sneezes, a vapor containing tiny droplets of saliva and mucous encapsulate the virus and disburse it into the surrounding air. This "aerosol effect" allows the virus to be easily inhaled by the new host or hosts, making influenza difficult to contain during an outbreak--especially in large metropolitan areas where people use mass transport systems such as buses and subways.
In the case of avian flu, bird droppings are the transmission point between infected birds and the spread of the virus to mammals. Recent cases of H5N1, which hit international headlines, were primarily traced back to direct contact with infected birds and people who lived and worked in close proximity to them. Though this particular strain of influenza has not become "airborne" (transmitted from infected animals to hosts through the air via coughing or sneezing), earlier pandemics have shown that this mutation of the virus is possible. The pandemic virus of 1918 claimed nearly 100 million lives around the world. It began as an avian flu that crossed the species barrier and then became airborne.
Protect Yourself
Influenza can also be highly persistent. Contaminated surfaces such as countertops, doorknobs and anything else an infected person may touch can transmit the virus. The flu virus can live for up to 1 week at human body temperature but can live for more than 1 month at cooler temperatures (nearer freezing).
However, most forms of flu are easily killed with antiseptic or antibacterial cleaning products. And good hygiene remains the best protection against the spread of influenza. Frequent washing of hands, and wiping counters, doors, telephones and any other surface with which an infected person may come in contact, will significantly reduce the chances of infection.
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