What is Influenza?

• Basic Information
• What is a Pandemic?
• Non-Pharmaceutical Interventions
• Flu Transmission Maps
• References
• Testimonials

Influenza

Influenza is a highly contagious viral infection that primarily attacks the respiratory tract, including the nose, throat, and bronchi and on rare occasions, the lungs. It usually lasts for about a week and is characterized by the sudden onset of high fever, myalgia (muscle pain), headaches, severe malaise, non-productive cough, sore throat, and rhinitis. (2) In addition to the direct effects of an influenza infection, there can be many complications. Influenza can worsen chronic heart disease, lung disease and diabetes, and can lead to bacterial or viral pneumonia. For many people, these complications create a lethal combination. (4)

Flu viruses spread mainly from person to person by droplet transmission when viruses are emitted through droplets from talking, coughing and sneezing. People can also become infected if their hand becomes contaminated and comes in contact with their eyes, nose or mouth. (3)

Flu outbreaks seasonally occur with onset in the late fall or winter. The disease is easily spread from person to person and can travel quickly through communities to create an epidemic. Between 1976 and 2006, influenza activity in the United States has peaked most often during the month of February. (7)

Avian Influenza and Animal Reservoirs of Disease

Over the past ten years, more than two-thirds of emerging diseases have been traced back to either wild or domestic animal origins. (1) The circulating flu virus was originally introduced to humans from birds, influenza's natural reservoir. At several points in the past, a new strain of the flu virus acquired the ability to infect humans, resulting in the three flu pandemics of the 20th century, which occurred in 1918, 1957, and 1968. Click here to learn more about how the 1918 flu pandemic affected Ann Arbor and what UM students did to help.

H5N1 (avian influenza A) is the particular subtype of influenza virus that is causing the current epidemic in birds. The virus is found in the saliva, nasal secretions, and feces of infected birds. Close contact with infected birds or contaminated surfaces can lead to infections in humans. (5) Symptoms of human cases of avian influenza have ranged from typical influenza-like symptoms to eye infections, pneumonia, acute respiratory distress, viral pneumonia, and other severe and life-threatening complications.

Follow this link for a World Health Organization update on avian influenza:

• http://www.who.int/csr/disease/avian_influenza/en/