Public Domain. For more information: www.cdc.gov. Additional source description and credit info from source:
Suggested credit: CDC/ Dr. F. A. Murphy [via pingnews].
Description: This negative-stained transmission electron micrograph
(TEM) depicts the ultrastructural details of a number of influenza
virus particles, or “virions”. A member of the taxonomic family
Orthomyxoviridae, the influenza virus is a single-stranded RNA
The flu is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, and at times can lead to death. The best way to prevent this illness is by getting a flu vaccination each fall.
Every year in the United States, on average:
- 5% to 20% of the population gets the flu
- more than 200,000 people are hospitalized from flu complications, and
- about 36,000 people die from flu. Some people, such as older people, young children, and people with certain health conditions, are at high risk for serious flu complications.
Influenza A and B are the two types of influenza viruses that cause
epidemic human disease. Influenza A viruses are further categorized
into subtypes on the basis of two surface antigens: hemagglutinin and
neuraminidase. Influenza B viruses are not categorized into subtypes.
Since 1977, influenza A (H1N1) viruses, influenza A (H3N2) viruses,
and influenza B viruses have been in global circulation. In 2001,
influenza A (H1N2) viruses that probably emerged after genetic
reassortment between human A (H3N2) and A (H1N1) viruses began
circulating widely. Both influenza A and B viruses are further
separated into groups on the basis of antigenic characteristics. New
influenza virus variants result from frequent antigenic change (i.e.,
antigenic drift) resulting from point mutations that occur during
viral replication. Influenza B viruses undergo antigenic drift less
rapidly than influenza A viruses.
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Content Providers(s): CDC/ Dr. F. A. Murphy
Creation Date: 1973