Avian Influenza A(H3) Viruses
In Asia, viruses known as LPAI A(H3N8) have been found in wild birds and poultry. A(H3N8) virus infections have been reported in China in a limited number of cases; two of these cases have resulted in severe pneumonia and one death, and one case has only mild illness.
Avian Influenza A(H7) Viruses
The A(H7) virus has nine subtypes that are currently recognized: A(H7N1), A(H7N2), A(H7N3), A(H7N4), A(H7N5), A(H7N6), A(H7N7), A(H7N8), and A(H7N9). The majority of A(H7) viruses found in wild birds and poultry across the globe are LPAI viruses. Avian influenza A(H7) virus infection of humans have occurred sporadically. Bird flu A(H7N9) viruses, which were discovered in China in 2013, are the most commonly found A(H7) viruses linked to human infections. Despite being uncommon, human infections with A(H7N9) viruses have caused severe respiratory illnesses and fatalities in about 2040% of cases that have been reported. In addition to A(H7N9) viruses, human infections with A(H7N2), A(H7N3), A(H7N4), and A(H7N7) viruses have also been documented. These infections have mainly resulted in mild to moderate illness, with symptoms such as upper respiratory tract symptoms and/or conjunctivitis.
Subtypes of Influenza A Viruses
Hemagglutinin (HA) and neuraminidase (NA), two proteins on the virus’s surface, are used to categorize influenza A viruses into subtypes. Eleven known NA subtypes and eighteen known HA subtypes exist. There are 16 HA and 9 NA subtypes known in birds. (Two more subtypes in bats, H17N10 and H18N11, have been discovered.) It is possible to combine HA and NA proteins in a wide variety of ways. For instance, an influenza A virus subtype with the HA 7 and NA 2 proteins is referred to as an “A(H7N2) virus.” Similar to this, the “A(H5N1)” virus possesses the HA 5 and NA 1 proteins.
Birds can contract influenza A viruses from any known subtype, with the exception of subtypes A(H17N10) and A(H18N11), which are exclusively detected in bats. There are currently only two influenza A virus subtypes that are circulating in humans: A(H1N1)pdm09 and A(H3N2). Seven distinct animal species or groupings, including humans, domestic poultry, swine, horses, dogs, and bats, have been found to harbor influenza A viruses. Avian influenza A viruses have been known to occasionally infect many other animal species, but they do not frequently spread among them (e g. , cats and seals). Canine influenza A(H3N2) virus regularly circulates and can infect dogs, and equine influenza A(H3N8) virus regularly circulates and can infect horses.
FAQ
Is bird flu the same as flu type A?
What is the flu type A?
What is the name of the bird flu?
Is flu A or B worse?