Objective
To analyze clinical and epidemiological characteristics of the first human case of H5N6 avian influenza in Hefei City, and to provide a scientific basis for control and prevention of similar animal-origin influenza outbreaks in humans.
Methods
Field epidemiological investigation methods were used to collect and analyze basic information of the case, course of illness and medical consultation, history of poultry exposure, tracking and screening of close contacts, and testing results of relevant specimens.
Results
The case was an elderly female who presented with flu-like symptoms in the early stages of illness. The condition progressed rapidly, with time intervals from onset to first consultation, hospitalization, conversion to severe condition, use of anti-influenza drugs, laboratory confirmation, and death being 1 day, 2 days, 2 days, 4 days, 7 days, and 22 days, respectively. The patient had a clear history of exposure to live poultry (chickens), and the positive rate of H5N6 virus in the supply market environment was 20.00%. The results of gene sequencing showed that, the HA gene segment belongs to the same lineage as H5N6 strains isolated from chickens and crows in Japan in 2022 and 2023, and the H5N6 strain isolated from cats in South Korea in 2023; while the NA gene segment belongs to the same lineage as H5N6 strains isolated from mandarin ducks in South Korea in 2023 and from wild birds in Zhejiang, China in 2024. Expanded surveillance revealed that the positive rate of H5N6 in environmental samples from markets with live poultry sales was significantly higher than that in markets without live poultry sales (60.00% vs. 1.27%, χ2=88.364, P<0.001). No secondary cases were found among the 44 close contacts and co-exposed individuals.
Conclusion
This is the first human case of H5N6 avian influenza in Hefei City, with the source of infection being exposure to live poultry. The sale of live poultry is a risk factor for human infection with H5N6 avian influenza. It is recommended to prohibit the trade of live poultry in urban areas and even the entire city, promote centralized slaughter, cold chain transportation, and fresh poultry sales policies, strengthen public health education, encourage citizens to purchase and consume "qualified poultry", and reduce direct contact with live poultry to lower the risk of infection.