#19,370
Last April 2nd, in
Taiwan CDC: Human Infection with a Novel H7 Avian Virus, we looked at a lengthy report on Taiwan's first detection of a locally acquired human H7 LPAI infection in a poultry farmer.
The patient (a man reportedly in his 70s) was hospitalized with fever on March 22nd and subsequently developed pneumonia. He remained hospitalized and in isolation in early April, although his condition was said to be improving.
The CDC also reported:
Currently, 33 close contacts are under health monitoring and management, and 3 have been given preventative medication based on risk assessment. Tests were conducted on 6 family members, all of whom tested negative.
The following day, we saw another
Taiwan CDC Update: Novel H7 Infection Identified as H7N7. We also saw
a letter to physicians posted on April 8th. At that time only the HA (H7) has been identified, with additional tests still pending.
We looked at a follow-up statement in early May (see
Taiwan CDC: Statement/Update On Locally Acquired H7N7 Infection) after additional testing revealed the virus's PB2 gene carried the E627K mutation (
PB2 E627K).
PB2-627K -
which can often develop after a human/mammal is infected - is associated with enhanced replication and pathogenicity in mammals (see
A rapid review of the avian influenza PB2 E627K mutation in human infection studies).
Yesterday an unusually terse (
the abstract run just 50 words) preprint was posted on the
medRxiv server which fills in some of the gaps on this event.
We learn that virus (
A/Taiwan/1/2026) was a low-pathogenic H7N7 bird flu virus from the wild-bird gene pool of Eurasia. The authors wrote:
Although the HA and M genes clustered with an A/environment/Kagoshima/KU-24-D10/2024(H7N7)-like virus isolated in Japan, the other gene segments were most closely related to different source viruses. Across the genome, 138A/Taiwan/1/2026 is distantly related to previously detected viruses from Taiwan and to reported human H7 viruses from China, Europe, and North America.
The authors stated this suggests a recent spillover from a
wild bird gene pool, as the virus is distinct from earlier H7N7 poultry viruses which have spilled over into humans.
While it carried the PB2 E627K mammalian-adaptation marker, the authors cannot say whether that mutation was present in the bird host or arose post-infection in the patient (although the latter is suspected).
Although no avian influenza virus was reported to have been detected in the duck farms visited by the patient, the authors suggest:
Based on the patient's occupation background, domestic ducks at the workplace may have served as an intermediate source of infection after introduction of the virus into Taiwan by migratory birds. However, direct exposure to migratory birds or their feces could not be excluded.
None of the contacts tested showed serological evidence of infection.
Follow the link to read the preprint in its entirety. I'll return after the break with a postscript.
Human Infection with Avian Influenza A(H7N7) Virus, Taiwan, 2026
Yao-Tsun Li, Yun-Tong Lin, Bao-Shan Chen, Chuan-Yi Kuo, Hsiang-Yi Huang, Hui-Ying Ko, Pei-Yu Huang, Gavin JD Smith, Yi-Ling Lin, Ming-Tsan Liu
doi:
https://doi.org/10.64898/2026.10.09.26365013
This article is a preprint and has not been certified by peer review [what does this mean?].
Preview PDF
Abstract
Low pathogenic avian influenza A(H7N7) virus detected in a poultry worker in Taiwan, 2026 was related to viruses circulating in Asian wild birds and possessed
PB2 E627K, a mammalian adaptation marker. Enhanced surveillance for H7 viruses in poultry and rapid characterization of human cases are essential to assess pandemic potential.
(Continue . . . )
While H5Nx gets most of our attention these days, H7 viruses have a fairly impressive track record of their own.
- In 2003, the Netherlands saw an outbreak of H7N7 that resulted in the loss of 30 million birds across 1,000 farms, and saw scores of mild human infections and the death of a veterinarian (see Eurosurveillance Human-to-human transmission of avian influenza A/H7N7, The Netherlands, 2003).
- Another analysis, performed by the RIVM (Ministry of Health) found the spread of the virus to be much greater than originally reported, citing as many as 1,000 human infections (see Executive summary Avian Flu Epidemic 2003: Public health consequences).
- Smaller H7 outbreaks, including the 2004 H7N3 outbreak in British Columbia, a small number of human infections in Wales in 2007, and 3 mild cases in Italy in 2013 (see ECDC : Human Infection By Avian H7N7 In Italy) were also reported.
- But the 5-year epidemic of H7N9 in China (2013-2018) - which hospitalized more than 1,500 people, killing roughly 40% of them - demonstrate just how formidable an H7 virus can be.
NYC's 2016 dramatic H7N2 outbreak in hundreds of cats, and spillover into animal shelter workers (see
J Infect Dis: Serological Evidence Of H7N2 Infection Among Animal Shelter Workers, NYC 2016) - and a
2018 report of a severe H7N4 infection out of China - further illustrate the risks.
Of the 27 novel influenza viruses ranked by the CDC using their IRAT tool, H7 viruses make up 2 of the top 5 (in terms of emergence), and rank higher (in terms of impact) than any of the H5Nx viruses listed.
Which is why we continue to follow these cases with considerable interest.
https://afludiary.blogspot.com/2026/10/preprint-human-infection-with-avian.html
