Wednesday, June 19, 2024

WHO WPRO Reports 2nd H5N6 Case In Fujian, China In 2024


In a small notice in their most recent Avian Influenza Weekly Update Number 951, the Western Pacific office of the WHO announced the 2nd H5N6 case in China for 2024, which - like the one announced last month - was in Fujian Province. 

In both cases, no town was mentioned, only that both patients hailed from Fujian province (Pop. 38.5 million 46,873 mi²).   The first case was described as a `. . . woman in her 50s who had exposure to backyard poultry before the onset of symptoms on 13 April 2024.' She died on April 30th

We learn even less about today's case, only that it was a 41 year-old male with onset on May 8th.  No likely exposure is mentioned, only that the patient suffered severe pneumonia and has passed away. 

Human infection with avian influenza A(H5N6) virus 

Between 7 June to 13 June 2024, one new case of human infection with avian influenza A(H5N6) virus was reported to WHO in the Western Pacific Region. The case is a 41-year-old male from Fujian Province, with an onset of illness on 8 May 2024. The patient was hospitalized with severe pneumonia and the case was confirmed positive for A(H5N6) on 14 May. He subsequently passed away. To date, a total of 92 laboratory confirmed cases of human infection with influenza A(H5N6) virus, including 37 deaths (CFR 40%), have been reported to WHO in the Western Pacific Region since 2014. The last case was reported from China, with a symptom onset date of 13 April 2024.

Getting reliable, and timely, information out of China on avian flu has always been difficult, but it has arguably become even more challenging since the emergence of COVID.  Reports to the WHO are often delayed, and contain few details. 

Today's case was reported to the WHO relatively quickly, since the patient was confirmed positive on May 14th, and a notification was made `between June 7 & June 13th'.  Call it 3 or 4 weeks delay.   Not ideal, but far quicker than many other cases we've seen.

While China's H5+H7 poultry vaccination program which was launched in 2017 quickly eradicated the H7N9 virus, it appears to have been less successful in controlling H5N6.  Nearly all human cases report recent contact with live poultry, yet we almost never hear of a symptomatic outbreak in domesticated birds. 

Recent studies (see mSphere: An HPAI H5N6 Virus With Remarkable Tropism for Extra-respiratory Organs in the Ferret Model) suggest the H5N6 virus continues to adapt to mammalian hosts, while 2 years ago the Lancet published Resurgence of H5N6 Avian Influenza Virus in 2021 Poses New Threat to Public Health.

H5N6 - along with Cambodia's clade H5N1 virus - remind us that HPAI H5 continues to explore multiple evolutionary paths, and that we may see others emerge over time.