influenzavírus

Influenza virus, commonly known as the flu virus, is a genus of viruses in the family Orthomyxoviridae. These viruses are responsible for causing influenza, a contagious respiratory illness that can affect people of all ages. There are four main types of influenza viruses: A, B, C, and D. Influenza A and B viruses cause seasonal epidemics in humans, while influenza C viruses usually cause mild respiratory illness and do not cause epidemics. Influenza D viruses primarily affect cattle and are not known to infect humans.

Influenza viruses are RNA viruses, meaning their genetic material is ribonucleic acid. They are characterized by their segmented genome, which allows for genetic reassortment. This reassortment, along with genetic drift, leads to the continuous emergence of new strains of influenza viruses, which is why seasonal flu vaccines are updated annually. The virus is transmitted through respiratory droplets produced when an infected person coughs, sneezes, or talks.

Symptoms of influenza typically include fever, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches, and fatigue. Some people may experience vomiting and diarrhea, though this is more common in children than adults. While most people recover from influenza within a few days to less than two weeks, some can develop complications such as pneumonia, bronchitis, sinus infections, and ear infections. Influenza can be serious, leading to hospitalization and even death, particularly in young children, older adults, pregnant women, and individuals with certain chronic health conditions.