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Two weeks ago the CDC authorities in Guangdong Province, China reported that country's 3rd H3N8 human infection in a year; in a 56 year-old female with existing medical conditions, who reportedly died on March 16th.
Earlier today we saw a brief update from the WHO WPRO on this case, and hopefully we'll get more details in the days to come.
Today the CDC has posted the following statement on this 3rd case, which may have been written before the the WHO statement we saw earlier today, as it does not mention the patient's recently revealed fatal outcome.
Human Infection with Avian Influenza A(H3N8) Virus Reported by China
Background:
Updated April 10, 2023
April 10, 2023—The Guandong Provincial Center for Disease Control and Prevention reported a human infection with avian influenza A(H3N8) virus in China, or “H3N8 bird flu” on March 26, 2023. This is the third human infection with H3N8 bird flu viruses ever reported. The previous two H3N8 virus infections were also reported in China, during 2022. H3N8 viruses are a different influenza A virus subtype and unrelated to H5N1 viruses currently spreading among wild birds and poultry in the United States and globally. This human case of H3N8 virus infection is not thought to pose a risk to U.S. public health at this time.
Background:
Sporadic human infections with bird flu viruses occur, including with different bird flu virus subtypes. Over the past two decades, H7N9 viruses have caused the highest number of human infections, followed by H5N1 viruses, which have caused the second highest number of human infections. Most human infections with avian influenza A viruses have resulted from direct contact with, or close exposure to, infected birds/poultry.
- H3N8 viruses were first detected in wild birds in the 1960s and have been detected in other animals.
- Avian influenza H3N8 viruses have been sporadically detected in poultry in China and some have been found to be genetically closely related to the human cases reported in 2022 [1].
Information on H3N8 Human Infections:
According to a statement from the Guandong Provincial Center for Disease Control and Prevention, the third human infection with H3N8 virus occurred in an adult in China who reportedly had a history of exposure to live poultry and wild birds (which had been observed around the home). An investigation did not find any additional human infections, and officials believe the risk of the virus spreading further at this point is low.
Both of the human infections with H3N8 viruses in 2022 were in children. The first infection was in a child who had exposure to backyard chickens and wild ducks in April 2022 [3]. The patient became critically ill and was hospitalized for their illness [2, 3]. The second infection occurred in May 2022 in a child who visited a wet market where live poultry were present [4]. That child had mild symptoms [4]. All close contacts of the first two reported cases tested negative for influenza A viruses, and both children recovered [2, 3, 4].
United States Situation:
H3N8 bird flu has never been detected in the United States in people; however, H3N8 viruses of a different genetic lineage have been detected in U.S. wild birds and some mammals in the past. In 2011, there was an outbreak of H3N8 viruses among harbor seals in New England that caused deaths in 162 seals [5].
In the United States, current bird flu preparedness and surveillance activities are largely focused on H5N1 bird flu, which is widespread in U.S. wild birds and has caused extensive outbreaks in U.S. poultry, with sporadic spillover to some mammals. The current risk to the U.S. general public from H5N1 bird flu viruses remains low at this time; however, it is important to remember that risk depends on exposure, and people with more exposure might have a greater risk of infection. CDC has guidance for specific groups of people with exposure to poultry, including poultry workers and people responding to poultry outbreaks. Additional information on protective actions around birds, including what to do if you find a dead bird, is available as well.
Currently, CDC does not recommend against travel to any countries due to bird flu viruses. CDC recommends that travelers to countries and states with bird flu outbreaks in poultry or people:
CDC is following global developments related to avian influenza closely and will continue to provide further updates to the situation and update guidance as needed.
- Do not visit poultry farms, bird markets, or other places where live poultry are raised, kept, or sold, if possible.
- Do not eat raw or undercooked poultry products and wash your hands after touching uncooked poultry.
- Practice good hygiene and cleanliness.
- Visit a doctor if you become sick during or after travel.
