how many types of bird flu are there

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.

Avian Influenza A(H5) Viruses

A(H5) viruses are classified into nine subtypes: A(H5N1), A(H5N2), A(H5N3), A(H5N4), A(H5N5), A(H5N6), A(H5N7), A(H5N8), and A(H5N9) viruses.

Most A(H5) viruses identified worldwide in wild birds and poultry are LPAI, but occasionally HPAI A(H5) viruses have been detected. Sporadic A(H5) virus infections of humans have occurred, such as with HPAI A(H5N1) viruses associated with poultry outbreaks in many countries. Human infections with HPAI A(H5N1) virus have been reported in 23 countries since 1997, resulting in severe pneumonia and death in about 50% of cases. Human infections with HPAI A(H5N6) virus have been reported since 2014 from two countries with death occurring in more than 40% of cases, and human infections with HPAI A(H5N8) virus were reported from one country in 2021.

Transmission edit Birds that have been put down because of avian influenza. The virus is spread by contact between healthy and unhealthy birds.

Although it can also spread indirectly through contaminated equipment, contact between sick and healthy birds is the primary way that avian influenza is spread. [34] Infected birds’ droppings and secretions from their mouths, noses, and eyes contain the virus. People frequently contract HPAI infection by coming into close contact with infected poultry, such as when plucking or slaughtering them. [34] The illness is not an airborne disease, even though the virus can spread through airborne secretions. Less dangerous strains may have an impact on egg production but are far less deadly; highly pathogenic strains can wipe out a flock in as little as 28 hours. [citation needed].

The avian influenza virus can infect humans, but it is much more difficult for it to spread from person to person if there is no sustained contact. According to public health officials, strains of avian flu could mutate to make it easier for people to contract from one another. [10] While many shorebirds and waterbirds have certain avian influenza strains in their digestive tracts, human infection by these strains is uncommon. [35].

The current avian influenza virus ecology is a result of five man-made ecosystems: backyard and hobby flocks, range-raised commercial poultry, live poultry markets, integrated indoor commercial poultry, and bird collection and trading systems, including cockfighting. The greatest influence on the spread of HPAI has been seen in indoor commercial poultry; since the 1990s, increased commercial production has largely been responsible for the rise in HPAI outbreaks. [13].

Early on in the HPAI H5N1 pandemic, village poultry and their owners were often linked to the spread of the illness. [13] Village poultry, sometimes referred to as backyard and hobby flocks, are tiny flocks that are raised in harsh circumstances and frequently given the freedom to roam between several homes. Subsequent investigation revealed that these flocks are not as dangerous as commercial poultry raised intensively with uniform genetic stock and inadequate biosecurity. [13] In addition, backyard and village poultry do not spread HPAI as much as poultry raised intensively because they do not travel as far. [36].


How many strains of bird flu are there?

Five subtypes of avian influenza A viruses are known to have caused human infections (H5, H6, H7, H9, and H10 viruses). The most frequently identified subtypes of avian influenza A viruses that have caused human infections are H5, H7 and H9 viruses.

What is the most common type of bird flu?

Bird flu, or avian influenza, is a viral infection spread from bird to bird. The most common kind of bird flu is the H5N1 strain. It’s mostly a threat to birds and doesn’t spread easily among people, but there was a major outbreak of bird flu in people in 2014.

What is the deadliest form of avian flu?

H5N1, classified as a highly pathogenic avian influenza (HPAI) virus because of its high death toll in poultry, was first detected in birds in China in 1996.

What is the difference between bird flu and avian flu?

Bird flu, also known as avian influenza, is a type A influenza virus. It is lethal to poultry and is potentially fatal in humans. Bird flu spreads between both wild and domesticated birds.