Tragically, many serious cases of flu and even deaths could be prevented through annual immunizations. While the flu itself is not usually fatal, some people, particularly the elderly and those who have a chronic illness, can develop life-threatening complications. Influenza, commonly called the flu, is caused by viruses that infect the respiratory tract.
Flu viruses can enter the body through the mucous membranes of the eyes, nose or mouth.
After a person has been infected with the virus, symptoms usually appear within two to four days. The infection is considered contagious for another three to four days after symptoms appear. Once a person has the flu, treatment usually consists of resting in bed, drinking plenty of fluids and taking medication to relieve fever and discomfort. Flu complications generally result from bacterial infections in the lower respiratory tract. Symptoms usually appear after the patient starts feeling better.