Influenza A virus subtype H7N2 | |
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Virus classification | |
(unranked): | Virus |
Realm: | Riboviria |
Kingdom: | Orthornavirae |
Phylum: | Negarnaviricota |
Class: | Insthoviricetes |
Order: | Articulavirales |
Family: | Orthomyxoviridae |
Genus: | Alphainfluenzavirus |
Species: | |
Serotype: | Influenza A virus subtype H7N2 |
Influenza (flu) |
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Influenza A virus subtype H7N2 (A/H7N2) is a subtype of the species Influenza A virus. This subtype is one of several sometimes called bird flu virus. H7N2 is considered a low pathogenicity avian influenza (LPAI) virus. [1] With this in mind, H5 & H7 influenza viruses can re-assort into the Highly Pathogenic variant if conditions are favorable.
A CDC study following outbreaks of H7N2 in commercial poultry farms in western Virginia in 2002 concluded:
One person in Virginia, United States in 2002, one person in New York, United States, in 2003, and one person in New York, United States, in 2016 [3] were found to have serologic evidence of infection from H7N2; all fully recovered.
An analysis of the New York 2003 case concluded that the H7N2 virus responsible could be evolving toward the same strong sugar-binding properties of the three worldwide viral pandemics in 1918, 1957 and 1968. (Human flus and bird flus differ in the molecules they are good at binding with because mammals and birds differ in the molecules on the cell surface to be bound with. Humans have very few cells with the bird sugar on its cell surface.) A study with ferrets showed that this H7N2 strain could be passed from mammal to mammal. [4] [5]
In February 2004, an outbreak of low pathogenic avian influenza (LPAI) A (H7N2) was reported on 2 chicken farms in Delaware and in four live bird markets in New Jersey supplied by the same farms. In March 2004, surveillance samples from a flock of chickens in Maryland tested positive for LPAI H7N2. It is likely that this was the same strain. [6]
On 24 May 2007, an outbreak of H7N2 was confirmed at a poultry farm near Corwen, in Wales from tests on chickens that died from H7N2. The owners of the Conwy farm bought 15 Rhode Island Red chickens two weeks prior but all died from H7N2. The 32 other poultry at the site were slaughtered. A one kilometer exclusion zone was put in force around the property in which birds and bird products cannot be moved and bird gathering can only take place under licence. Nine people who were associated with the infected or dead poultry and reported flu-like symptoms were tested. Four tested positive for evidence of infection from H7N2 and were successfully treated for mild flu. [7] In early June it was discovered that the virus had spread to a poultry farm 70 miles (113 km) away near St. Helens in north-west England. All the poultry at the farm were slaughtered and a 1 km exclusion zone imposed. [8]
In December 2016, an outbreak of low pathogenic avian influenza H7N2 occurred in a feline population in the New York City Animal Care Center (ACC) shelters after testing by the University of Wisconsin-Madison School of Veterinary Medicine and confirmed by USDA's National Veterinary Diagnostic Services Laboratory. [9] Over 100 cats were found to be infected and subsequently quarantined, but only one human, a veterinarian involved in obtaining respiratory specimens, was found to be infected. The veterinarian had a brief illness with mild symptoms and recovered completely. All other humans exposed to the infected cats tested negative. [3]
Influenza A virus (IAV) causes influenza in birds and some mammals, and is the only species of the genus Alphainfluenzavirus of the virus family Orthomyxoviridae. Strains of all subtypes of influenza A virus have been isolated from wild birds, although disease is uncommon. Some isolates of influenza A virus cause severe disease both in domestic poultry and, rarely, in humans. Occasionally, viruses are transmitted from wild aquatic birds to domestic poultry, and this may cause an outbreak or give rise to human influenza pandemics.
Avian influenza, known informally as avian flu or bird flu, is a variety of influenza caused by viruses adapted to birds. The type with the greatest risk is highly pathogenic avian influenza (HPAI). Bird flu is similar to swine flu, dog flu, horse flu and human flu as an illness caused by strains of influenza viruses that have adapted to a specific host. Out of the three types of influenza viruses, influenza A virus is a zoonotic infection with a natural reservoir almost entirely in birds. Avian influenza, for most purposes, refers to the influenza A virus.
Influenza A virus subtype H5N1 (A/H5N1) is a subtype of the influenza A virus which can cause illness in humans and many other animal species. A bird-adapted strain of H5N1, called HPAI A(H5N1) for highly pathogenic avian influenza virus of type A of subtype H5N1, is the highly pathogenic causative agent of H5N1 flu, commonly known as avian influenza. It is enzootic in many bird populations, especially in Southeast Asia. One strain of HPAI A(H5N1) is spreading globally after first appearing in Asia. It is epizootic and panzootic, killing tens of millions of birds and spurring the culling of hundreds of millions of others to stem its spread. Many references to "bird flu" and H5N1 in the popular media refer to this strain.
The global spread of H5N1 influenza in birds is considered a significant pandemic threat. While other H5N1 influenza strains are known, they are significantly different on a genetic level from a recent, highly pathogenic, emergent strain of H5N1, which was able to achieve hitherto unprecedented global spread in 2008. The H5N1 strain is a fast-mutating, highly pathogenic avian influenza virus (HPAI) found in multiple bird species. It is both epizootic and panzootic. Unless otherwise indicated, "H5N1" in this timeline refers to the recent highly pathogenic strain of H5N1.
Transmission and infection of H5N1 from infected avian sources to humans has been a concern since the first documented case of human infection in 1997, due to the global spread of H5N1 that constitutes a pandemic threat.
H5 N2 is a subtype of the species Influenzavirus A. The subtype infects a wide variety of birds, including chickens, ducks, turkeys, falcons, and ostriches. Affected birds usually do not appear ill, and the disease is often mild as avian influenza viral subtypes go. Some variants of the subtype are much more pathogenic than others, and outbreaks of "high-path" H5N2 result in the culling of thousands of birds in poultry farms from time to time. It appears that people who work with birds can be infected by the virus, but suffer hardly any noticeable health effects. Even people exposed to the highly pathogenic H5N2 variety that killed ostrich chicks in South Africa only seem to have developed conjunctivitis, or a perhaps a mild respiratory illness. There is no evidence of human-to-human spread of H5N2. On November 12, 2005 it was reported that a falcon was found to have H5N2.
Influenza A virus subtype H7N7 (A/H7N7) is a subtype of Influenza A virus, a genus of Orthomyxovirus, the viruses responsible for influenza. Highly pathogenic strains (HPAI) and low pathogenic strains (LPAI) exist. H7N7 can infect humans, birds, pigs, seals, and horses in the wild; and has infected mice in laboratory studies. This unusual zoonotic potential represents a pandemic threat.
Influenza A virus subtype H7N3 (A/H7N3) is a subtype of the species Influenza A virus.
H5N8 is a subtype of the influenza A virus and is highly lethal to wild birds and poultry. H5N8 is typically not associated with humans. However, seven people in Russia were found to be infected in 2021, becoming the first documented human cases.
H5N1 genetic structure is the molecular structure of the H5N1 virus's RNA.
The global spread of H5N1 in birds is considered a significant pandemic threat.
The global spread of H5N1 in birds is considered a significant pandemic threat.
The global spread of H5N1 in birds is considered a significant pandemic threat.
Fujian flu refers to flu caused by either a Fujian human flu strain of the H3N2 subtype of the Influenza A virus or a Fujian bird flu strain of the H5N1 subtype of the Influenza A virus. These strains are named after Fujian, a coastal province in Southeast China.
The global spread of H5N1 in birds is considered a significant pandemic threat.
Influenza, commonly known as "the flu", is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue. These symptoms begin from one to four days after exposure to the virus and last for about 2–8 days. Diarrhea and vomiting can occur, particularly in children. Influenza may progress to pneumonia, which can be caused by the virus or by a subsequent bacterial infection. Other complications of infection include acute respiratory distress syndrome, meningitis, encephalitis, and worsening of pre-existing health problems such as asthma and cardiovascular disease.
H5N6 is a subtype of the species Influenza A virus. Infected birds shed the virus in their saliva, mucous, and feces. The virus was first detected in poultry in 2013, since then spreading among wild bird populations and poultry around the world. Humans can be infected through unprotected contact with infected birds or contaminated surfaces. The virus transmits by getting into a person's eyes, nose, mouth, and through inhalation. Human infections are rare. Since 2014, at least 65 cases have occurred in humans. 29 people have died. A spike in human cases was reported in 2021. There have been no confirmed cases of human-to-human transmission. Some infections have been identified where no direct contact with infected birds or contaminated surfaces has been known to had occurred. Only one infected woman has said that she never came into any contact with poultry.
In 2015, an outbreak of avian influenza subtype H5N2 was identified in a series of chicken and turkey farming operations in the Midwestern United States. By May 30, more than 43 million birds in 15 states had been destroyed as a result of the outbreak, including nearly 30 million in Iowa alone, the nation's largest egg producer. In the Midwestern U.S., the average price of eggs had increased 120% between April 22 and May 30. The effects however were seen nationwide, with prices in California up 71% in the same timeframe.
In the early 2020s, an ongoing outbreak of avian influenza subtype H5N8 has been occurring at poultry farms and among wild bird populations in several countries and continents, leading to the subsequent cullings of millions of birds to prevent a pandemic similar to that of the H5N1 outbreak in 2008. The first case of human transmission was reported by Russian authorities in February 2021, as several poultry farm workers tested positive for the virus.
Influenza A virus subtype H10N3 is a subtype of viruses that causes influenza (flu). It is mostly present in wild avian species. The first human case was reported in 2021.