HKCHP Reports 1 New H10N3 Case On Chinese Mainland (Guangxi)

 

#18,458

Although there is no mention of it in China's latest Weekly Influenza Report, today Hong Kong's Weekly Avian Influenza Report VOLUME 21, NUMBER 2, carries the cryptic graphic above showing 2 recent H9N2 cases and 1 H10N3 case.

As is so often the case, we get little or no details. Only that they exist. Hopefully we'll get more details from the next WHO report.

Over the past 6 months China has reported 11 other H9N2 cases (see Hong Kong CHP: 7 Recent H9N2 Cases Reported From the Mainland), a decided uptick in detection. 

While LPAI H9N2 is admittedly not at the very top of our list of pandemic concerns, the CDC has 2 different lineages (A(H9N2) G1 and A(H9N2) Y280) on their short list of influenza viruses with zoonotic potential (see CDC IRAT SCORE), and several candidate vaccines have been developed.

Only about 140 cases have been officially reported over the past 20 years (see FluTrackers list), and most (but not all) of them have reported mild or moderate illness. Seroprevalence studies, however, suggest the infection is far more common than we believe. 

Of considerably more interest is the announcement of a 4th H10N3 case in China since 2021. 

• In June of 2021 China's NHC Reported the 1st Human H10N3 Avian Flu Infection - Jiangsu Province)
• Followed in 2022 by A Cryptic Report of A 2nd H10N3 Case from Hong Kong's CHP.
• In April of 2023 a 3rd case was reported from Yunnan Province (see Nature Portfolio preprint).

Last July, in Frontiers: Phylogenetic and Mutational Analysis of H10N3 Avian Influenza A virus in China: Potential Threats to Human Health, we looked at a report that described 4 mutations of concern in the 2023 case (HA Q226L, PB2 D701N, PA S409N, and M2 S31N), along with the patient's treatment and course of illness.

Less than a month ago, in Vet. Microbiology: The novel H10N3 Avian Influenza Virus Acquired Airborne Transmission Among Chickens: An Increasing Threat to Public Health, which reported the virus has become better adapted to poultry, is highly pathogenic in mice, can be transmitted via respiratory droplets between guinea pigs, and can also be transmitted via the airborne route by chickens.

They also reported on a serology study of poultry workers, which found a small but significant (1.5%) positivity rate. 

The overarching message from these reports is that avian influenza viruses continue to expand - both in range and variety - across China and the rest of the globe, and that some of these viruses pose legitimate public health risks.

Although China remains tight-lipped about their avian flu problem, last week we did see a decree from Shanghai Banning Live Poultry Sales. Why now, and why in Shanghai, wasn't divulged. 

While HPAI H5 may have most of our attention, the reality is there are many more zoonotic threat out there in the wild, most of which are only poorly monitored.  All of which makes it very easy for us to get blindsided by something out of the blue.