Monday, March 27, 2023

China: Guangdong CDC Reporting 1 H3N8 Infection (Zhongshan City)

First two H3N8 cases in Humans April-May 2022,
Henan Province roughly 400 miles apart


We've a curious report this morning from the Guangdong Provincial CDC announcing a single avian H3N8 infection has been detected in Zhongshan City (pop 4.4 million), which sits across the Pearl River Delta about 60 miles from Hong Kong. 

Assuming this case is confirmed, it would become China's 3rd reported case in less than a year (see the 1st and 2nd case reports). 

Notably in the first (severe) case, the family dog and cat both tested positive for H3N8, and a full-length HA sequencing revealed the HA to be identical to the boy's. 

Last summer we followed a number of reports on these two cases in China, and somewhat ominously, the detection of H3N8 in Hong Kong's poultry roughly 1000 km away from the first human case. 

The following brief announcement (below) provides remarkably little information, other than the age, gender, and location of the case.  No onset date is provided, although it is worded as if the investigation is ongoing, and the woman's condition is not disclosed. 

I'll have a bit more after the break. 


One H3N8 case reported in Zhongshan City

Source of information: This website Release date: 2023-03-26 

One case of H3N8 was reported in Zhongshan City. The case was a 56-year-old female with multiple myeloma and other basic medical history. She had a history of exposure to live poultry before the onset of the disease, and a history of wild bird activities around her home. The Chinese Center for Disease Control and Prevention checked and tested the case specimens, and the result was positive for H3N8 avian influenza virus nucleic acid.

Our center has guided Zhongshan City to carry out epidemiological investigations, close contact tracking management, investigation of epidemic-related places, on-site elimination and other epidemic disposal work in accordance with relevant plans. No abnormalities have been found in close contacts so far. Experts believe that this case is a sporadic case, and the risk of virus transmission is low at this stage.
Experts suggest that the public should try to avoid direct contact with live poultry and dead poultry in daily life; take personal protection, pay attention to food hygiene, separate raw and cooked meat, and cook meat thoroughly before eating; once you find fever, cough, throat People with respiratory symptoms such as pain should wear a mask and seek medical treatment as soon as possible. If they have been in contact with birds before the illness, they should take the initiative to tell the doctor. Farmer's markets at all levels and types should abide by the "Guangdong Provincial Poultry Management Measures" and implement measures such as market poultry management and sanitation.

Since H3N8 doesn't tend to seriously impact poultry, and until 10 months ago was not considered much of a zoonotic threat, it has received relatively little attention. However:
  • 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).
  • about 60 years ago H3N8 jumped unexpectedly to horses, supplanting the old equine H7N7 and is now the only equine-specific influenza circulating the globe
  • 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).
  • 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.
  • And lastly, in 2015's 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.
So far China's state media has remained unusually silent on this case, and Hong Kong's CHP has yet to make an announcement.   

Hopefully we'll have more details soon.