Influenza A viruses, commonly referred to as flu A viruses, are a type of respiratory illness-causing virus belonging to the Orthomyxoviridae family. They are characterized by their distinct genome structure and surface antigens, which include hemagglutinin (HA) and neuraminidase (NA).
These viruses primarily infect birds, but they are also known to infect a wide range of other animals, including humans, pigs, horses, and occasionally even dogs and cats. Influenza A viruses are further classified into various subtypes based on the differences in their HA and NA proteins. The most common subtypes are H1N1, H1N2, and H3N2, which have been responsible for several influenza outbreaks in humans over the years.
Influenza A viruses are highly contagious and can spread easily from person to person through respiratory droplets expelled during coughing, sneezing, or talking. The infection can cause a wide range of symptoms, including fever, cough, sore throat, body aches, fatigue, and sometimes even severe respiratory complications.
Due to the ability of influenza A viruses to undergo rapid genetic changes, they pose a significant public health threat. These mutations can occur both through gradual changes known as antigenic drift or through the abrupt emergence of entirely new subtypes known as antigenic shift. This is why seasonal flu vaccines need to be regularly updated to keep up with the changing strains of influenza A viruses.
Influenza A viruses are a major concern worldwide, often leading to significant morbidity and mortality during flu seasons. Antiviral medications and vaccination are the primary means of preventing and controlling the spread of these viruses among individuals and communities.
