On 27 January 2024, the National Health Commission of the People’s Republic of China notified the World Health Organization (WHO) of one confirmed case of human coinfection with avian influenza A(H10N5) virus and seasonal influenza A(H3N2) virus. This is the first case of human infection with avian influenza A(H10N5) virus reported globally. The case occurred in a female farmer over 60 years of age, with a history of chronic comorbidities, from Xuancheng Prefecture, Anhui Province. She had onset of symptoms on 30 November 2023 and passed away on 16 December 2023. The authorities isolated seasonal influenza A(H3N2) subtype and avian influenza A(H10N5) subtype viruses from the patient’s samples on 22 January 2024, which were affirmed in confirmatory testing on 26 January 2024. The patient had exposure to live poultry, and poultry samples also tested positive for H10N5. No new suspected human cases have been detected through the investigation and testing done by authorities. Currently available epidemiologic information suggests that avian influenza A(H10Nx) viruses have not acquired the capacity for sustained transmission among humans. Thus, the likelihood of human-to-human spread is considered low.
On 27 January 2024, the National Health Commission of the Peoples Republic of China notified WHO of one confirmed case of human coinfection with influenza A(H10N5) virus and seasonal influenza A(H3N2) virus. This is the first case of human infection with avian influenza A(H10N5) virus reported globally.
The case occurred in a female farmer over 60 years of age from Xuancheng Prefecture, Anhui Province, who had onset of symptoms of cough, sore throat and fever on 30 November 2023. The patient, who had a history of chronic comorbidities, was admitted to a local hospital on 2 December 2023 for treatment and was then transferred on 7 December 2023 to a medical institution in Zhejiang Province as her condition became more severe. The patient was diagnosed with influenza A virus infection. She passed away on 16 December 2023. Zhejiang Province health officials isolated seasonal influenza A(H3N2) subtype and avian influenza A(H10N5) subtype viruses from the patient’s samples on 22 January 2024 after nucleic acid testing, viral culture and gene sequencing conducted by local health care facilities.
On 26 January 2024, the Chinese Center for Disease Control and Prevention conducted confirmatory testing on the samples from Zhejiang Province and verified the laboratory results. It was noted that the patient had not been vaccinated for seasonal influenza.
The patient had exposure to live poultry through the purchase of a duck on 26 November 2023. From the duck meat stored in the fridge, seven samples tested positive for H10N5, and two samples were positive for N5 (no result for haemagglutinin). The patient had no contact with pigs or other mammals. Environmental samples were collected from her home, and all tested negative.
Medical observation of all close contacts in Zhejiang and Anhui provinces has found no additional suspected cases. Retrospective case finding activities also did not identify any other cases during the same period.
Avian influenza infections are caused by influenza viruses which normally circulate in several types of wild and domestic birds but can also infect humans and other animal species. Infections in humans are usually sporadic and mostly due to direct contact with infected animals or contaminated environments. The primary risk factor for human infection appears to be exposure to either infected live or dead poultry or contaminated environments, such as live bird markets. Current zoonotic influenza viruses have not demonstrated sustained person-to-person transmission.
Avian influenza infections in humans can cause high fever, cough, sore throat, and muscle aches among other initial symptoms. Depending on the factors related to the virus and the infected host, the disease may quickly progress to severe lung infection (pneumonia), acute respiratory distress syndrome and even altered mental status or seizures.
Laboratory testing with reverse transcription polymerase chain reaction or other rapid molecular influenza assays (with similar high sensitivity and high specificity) are recommended when available. Prompt treatment based on antivirals and supportive care should be the priority. Through the Global Influenza Surveillance and Response System, WHO closely monitors avian and other zoonotic influenza viruses.