Influenssaviruksen

Influenssavirus is a genus of viruses in the family Orthomyxoviridae. It is responsible for causing influenza, commonly known as the flu, in humans and other mammals. There are four main types of influenza viruses: A, B, C, and D. Influenza A and B viruses cause seasonal epidemics in humans. Influenza C viruses typically cause mild respiratory illness, and influenza D viruses primarily affect cattle.

Influenza viruses are RNA viruses. They have a segmented genome, meaning their genetic material is divided into several pieces. This segmentation is a key factor in the virus's ability to evolve rapidly. Influenza A viruses are further classified into subtypes based on two surface proteins: hemagglutinin (HA) and neuraminidase (NA). For example, H1N1 and H3N2 are common subtypes that cause seasonal flu.

The virus spreads from person to person through respiratory droplets produced when an infected person coughs, sneezes, or talks. These droplets can land in the mouths or noses of people nearby or possibly be inhaled into the lungs. Less often, a person might get influenza by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes.

Symptoms of influenza typically include fever, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches, and fatigue. Some people may have vomiting and diarrhea, though this is more common in children. Most people recover in a few days to less than two weeks, but some people can develop complications, such as pneumonia, which can be life-threatening.

Vaccination is the most effective way to prevent influenza. Influenza vaccines protect against the influenza viruses that research indicates will be most common during the upcoming season. Antiviral drugs can also be used to treat influenza, helping to shorten the duration of illness and reduce the risk of complications.