The flu is a highly contagious respiratory infection that spreads easily from person to person, mainly when an infected person coughs or sneezes. Approximately 10 percent to 20 percent of Americans come down with it between November and March (the season for this illness). Common symptoms include cough, fever, and extreme exhaustion.
What Is the Flu?
Each winter, millions of people suffer from the flu, which is a highly contagious infection. It spreads easily from person to person, mainly when an infected person coughs or sneezes. Viruses that infect the nose, throat, and lungs cause the flu, which is the short name for influenza. The illness is usually a mild disease in healthy children, young adults, and middle-aged people. However, it can be life threatening in older adults and in people of any age who have chronic illnesses such as diabetes or heart, lung, or kidney diseases.
The flu is a respiratory infection caused by a variety of flu viruses. It differs in several ways from the common cold, which is a respiratory infection that is also caused by viruses. For example, people with colds rarely get fevers, headaches, or suffer from the extreme exhaustion that the flu viruses can cause.
(Click Flu Symptoms for more information.)
Outbreaks of the Flu
Outbreaks usually begin suddenly and occur mainly in the late fall and winter. The flu spreads through communities, creating an epidemic. During the epidemic, the number of cases peaks in about 3 weeks and subsides after another 3 or 4 weeks. Half of the population of a community may be affected. Schools are an excellent place for flu viruses to attack and spread. Therefore, families with school-age children have more infections than other families, with an average of one-third of the family members becoming infected each year.
(Click Flu Outbreaks for more information.)