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Although the highly pathogenic H5 and H7 influenza viruses tend to capture most of our attention when it comes to avian flu, we've seen instances of other avian subtypes occasionally jump to humans.
H9N2 is the most commonly reported, but we've also seen H10 viruses (see here, here, and here) jump to humans, and H6N1 infect humans (and dogs) in Taiwan. In 2006 serological evidence of H11 infection was detected in a hunter and 2 wildlife professionals with extensive histories of wild waterfowl and game bird exposure
Spillovers of other avian flu subtypes are assumed to happen occasionally, and so we keep an eye on any avian virus that show signs of jumping - or adapting to - non-avian hosts. Over the years, one subtype that we've paid a good deal of attention to is H3N8.
- First, because H3N8 remains a plausible cause of a global influenza pandemic that spread out of Russia in 1889-1900 (some researchers now suspect a coronavirus instead).
- Second, H3N2 remains endemic in wild birds around the world.
- Third, about 60 years ago H3N8 jumped unexpectedly to horses, and since the 1970s appears to have supplanted the old equine H7N7 and is now the only equine-specific influenza circulating the globe.
- Fourth, in 2004 the equine H3N8 virus mutated enough to jump to canines, and began to spread among greyhounds in Florida (see EID Journal article Influenza A Virus (H3N8) in Dogs with Respiratory Disease, Florida).
- Fifth, in 2011 avian H3N8 was found in marine mammals (harbor seals), and 2012’s mBio: A Mammalian Adapted H3N8 In Seals, provided evidence that this virus had recently adapted to bind to alpha 2,6 receptor cells, the type found in the human upper respiratory tract.
- Sixth, in 2015 in J.Virol.: Experimental Infectivity Of H3N8 In Swine we saw a study that found that avian (but not canine or equine) H3N8 could easily infect pigs.
- Seventh, in 2016, in PLoS One: Evidence of Subtype H3N8 Influenza Virus Infection among Pet Dogs in China, we looked at the species jump and adaptation of (EIV or CIV or AIV) H3N2 to a canine host.
- And lastly, just 6 months ago, in CCDC Weekly: Epidemiological and Genetic Characteristics of the H3 Subtype Avian Influenza Viruses in China, we looked at an overview of H3 viruses in wild birds and poultry across China that warned: Frequent mutations and reassortments increased the genetic diversity associated with altered virus virulence, transmission, and mammalian adaptation of H3 AIVs, posing a potential threat to animal and human health.
So, today's announcement from China's National Health Commission on the first known detection of avian H3N8 in a human shouldn't come as a complete surprise.
The case - involving a 4 year-old boy living in Henan Province - is currently thought to be a sporadic, one-off case.
But H3N8 has been knocking at the door for decades. So we need to keep an eye out for additional cases.
A case of human infection with H3N8 avian influenza found in Henan Province
Release time: 2022-04-26 Source: Office of Health Emergencies
The National Health Commission announced on April 26 that a case of human infection with H3N8 avian influenza was found in Henan Province .
The patient , male, 4 years old, now lives in Zhumadian City, Henan Province. Before the onset of the disease, the patient had raised chickens and black-bone chickens at home, and there were wild ducks around the home . He developed fever and other symptoms on April 5 , and was admitted to a local medical institution for treatment on the 10th due to aggravation of his condition . On the 24th , the Chinese Center for Disease Control and Prevention conducted a test on the patient specimen sent from Henan Province , and the result was positive for the H3N8 avian influenza virus. Henan Province carried out medical observation and sampling tests on the close contacts of the child, and no abnormality was found .
The National Health Commission has instructed Henan Province to carry out prevention and control in accordance with relevant plans, and organized experts to carry out risk assessments. Experts' preliminary assessment believes that the H3N8 avian influenza virus is of avian origin and has not yet had the ability to effectively infect humans.
H3N8 virus has been detected in horses, dogs, birds and seals worldwide , but no human cases of H3N8 have been reported . This outbreak is an occasional bird-to-human cross-species transmission, and the risk of a large-scale epidemic is low. Experts suggest that the public should avoid contact with sick and dead poultry in their daily lives, and try to avoid direct contact with live poultry; pay attention to dietary hygiene, and separate raw and cooked food during food processing; raise awareness of self-protection, and those with fever and respiratory symptoms should be Wear a mask and seek medical attention as soon as possible.
