Influenza, commonly known as ” the flu “, is an infectious disease caused by an influenza virus. Frequent hand washing reduces the risk of viral spread, as does wearing a surgical mask. Influenza spreads around the world in yearly outbreaks, resulting in about three to five million cases of severe illness and about , to , deaths. Symptoms of influenza can start quite suddenly one to two days after infection. It can be difficult to distinguish between the common cold and influenza in the early stages of these infections. Diarrhea is not usually a symptom of influenza in adults, [20] although it has been seen in some human cases of the H5N1 “bird flu” [32] and can be a symptom in children.
Research on influenza includes studies on molecular virology, how the virus produces disease pathogenesis, host immune responses, viral genomics, and how the virus spreads epidemiology. Note that clades and sub-clades that are genetically different from others are not necessarily antigenically different i. The most famous and lethal outbreak was the flu pandemic Spanish flu type A influenza, H1N1 subtype, which lasted into
This is called antigenic drift, which slowly creates an increasing variety of strains until one evolves that can infect people who are immune to the pre-existing strains. If you have a severe egg allergy, you should be vaccinated in a medical setting and be supervised by a doctor who is able to recognize and manage severe allergic conditions. Acta Paediatrica. See also: United States influenza statistics by flu season. Although some had concerns about the safety of the H1N1 vaccine, flu vaccines have a very good safety profile. One important basic research program is the Influenza Genome Sequencing Project, which was initiated in to create a library of influenza sequences and help clarify which factors make one strain more lethal than another, which genes most affect immunogenicity, and how the virus evolves over time.
The flu, also called influenza, is a respiratory infection caused by viruses. Each year, millions of Americans get sick with the flu. Sometimes it causes mild illness. But it can also be serious or even deadly, especially for people over 65, newborn babies, and people with certain chronic illnesses. The flu is caused by flu viruses that spread from person to person.