Monday, May 30, 2022

Hong Kong CHP Finally Notified Of 2nd H3N8 Case On the Mainland

Two cases in Henan Province roughly 400 miles apart


Although regular readers of this blog have been aware of it since last Thursday (see Another Curious Avian H3N8 Report From China), Hong Kong's Centre for Health Protection has announced that they have been notified (on May 30th) of Mainland China's 2nd avian H3N8 human infection in just over a month.

While any spillover of a novel flu virus to humans is noteworthy, those belonging to the H1, H2, and H3 HA subtypes are of particular concern because all known human influenza pandemics going back 130 years came from one of these 3 subtypes (see Are Influenza Pandemic Viruses Members Of An Exclusive Club?).

H3N8 is also of concern because it remains a plausible cause of a flu pandemic that spread out of Russia in the late 1800s, and because we've seen it jump successfully from birds to other species (equines, canines, and aquatic mammals) in recent decades (see overview in FAO/OIE/WHO Joint Rapid Risk Assessment Human infection with Influenza A(H3N8)).

Belated announcements of spillover events out of China are nothing new, as China tends to dispense `bad news' strategically, sometimes waiting weeks or even months (see here, here, and here).  Add in sporadic testing and surveillance, and our understanding of the situation on the ground grows even murkier. 

Today's announcement by HK's CHP follows, after which I'll have a postscript.
CHP notified of human case of avian influenza A(H3N8) in Mainland

The Centre for Health Protection (CHP) of the Department of Health today (May 30) received notification from the National Health Commission on a human case of avian influenza A(H3N8) in Hunan Province, and again urged the public to maintain strict personal, food and environmental hygiene both locally and during travel.

The case involves a 5-year-old boy living in Changsha, Hunan Province, who had visited a live poultry market before onset. He developed symptoms on May 9 and had recovered.

So far, two human cases of avian influenza A(H3N8) have been reported by Mainland health authorities.

"All novel influenza A infections, including H3N8, are notifiable infectious diseases in Hong Kong," a spokesman for the CHP said.

Travellers to the Mainland or other affected areas must avoid visiting wet markets, live poultry markets or farms. They should be alert to the presence of backyard poultry when visiting relatives and friends. They should also avoid purchasing live or freshly slaughtered poultry, and avoid touching poultry/birds or their droppings. They should strictly observe personal and hand hygiene when visiting any place with live poultry.

Travellers returning from affected areas should consult a doctor promptly if symptoms develop, and inform the doctor of their travel history for prompt diagnosis and treatment of potential diseases. It is essential to tell the doctor if they have seen any live poultry during travel, which may imply possible exposure to contaminated environments. This will enable the doctor to assess the possibility of avian influenza and arrange necessary investigations and appropriate treatment in a timely manner.

While local surveillance, prevention and control measures are in place, the CHP will remain vigilant and work closely with the World Health Organization and relevant health authorities to monitor the latest developments.

The public should maintain strict personal, hand, food and environmental hygiene and take heed of the advice below when handling poultry:
  • Avoid touching poultry, birds, animals or their droppings;
  • When buying live chickens, do not touch them and their droppings. Do not blow at their bottoms. Wash eggs with detergent if soiled with faecal matter and cook and consume the eggs immediately. Always wash hands thoroughly with soap and water after handling chickens and eggs;
  • Eggs should be cooked well until the white and yolk become firm. Do not eat raw eggs or dip cooked food into any sauce with raw eggs. Poultry should be cooked thoroughly. If there is pinkish juice running from the cooked poultry or the middle part of its bone is still red, the poultry should be cooked again until fully done;
  • Wash hands frequently, especially before touching the mouth, nose or eyes, before handling food or eating, and after going to the toilet, touching public installations or equipment such as escalator handrails, elevator control panels or door knobs, or when hands are dirtied by respiratory secretions after coughing or sneezing; and
  • Wear a mask if fever or respiratory symptoms develop, when going to a hospital or clinic, or while taking care of patients with fever or respiratory symptoms.
The public may visit the CHP's pages for more information: the avian influenza page, the weekly Avian Influenza Report, global statistics and affected areas of avian influenza, the Facebook Page and the YouTube Channel.

Ends/Monday, May 30, 2022
Issued at HKT 18:28

Seven months ago, in CCDC Weekly: Epidemiological and Genetic Characteristics of the H3 Subtype Avian Influenza Viruses in China, we looked at a rare, detailed, and highly informative overview of avian H3 viruses detected in wild birds and poultry across China. One which highlighted both H3N2 and H3N8 as growing threats.

Nine days ago, in Adaptation of Two Wild Bird-Origin H3N8 Avian Influenza Viruses to Mammalian Hosts, we looked at a study investigating the transmissibility and pathogenicity of two H3N8 LPAI viruses (GZA1 & XJ47) isolated from wild birds in China.

Although both wild strains could infect mice and guinea pigs, they produced few symptoms and very limited transmissibility. But - after conducting a serial passage study - both strains developed much higher virulence, and had picked up known mammalian adaptations (PA T97I and D701N in PB2).

While we continue to struggle with our persistant COVID pandemic, and are now faced with new challenges from Monkeypox and an as-yet-unexplained acute hepatitis syndrome in children, avian influenza continues its remarkable resurgence around the globe.
HK CHP Monitoring New H5N6 Infection In Guangxi Province
CDC Adds Zoonotic Avian A/H5N1 Clade To IRAT List

Two States (Michigan & Minnesota) Report HPAI Infection In Wild Foxes

CDC HAN Advisory On Human H5 Infection In The United States

Mexico: HPAI H7N3 Detected In Two Facilities In Southern Coahuila State
While it is possible that none of these avian viruses will ever acquire sustained and efficient human-to-human transmission, all it takes is for one of them to get lucky, and develop the right set of mutations. 

Since that has happened before, we can assume - that given enough time - it will happen again.