The recent occurrences of avian influenza outbreaks, observed last year, underscore the sobering reality of zoonotic influenza. These events emphasize that individuals of all ages are susceptible, regardless of comorbidities, and that various exposures can lead to avian influenza infection. Scientists’ ability to analyze these viruses and map their evolutionary paths within phylogenetic trees is noteworthy.
The diverse range of zoonotic influenza viruses responsible for human infections in 2023 is concerning. Some strains caused severe illness with high mortality rates. Although person-to-person transmission was limited that year, the potential for future pandemics remains a constant concern, necessitating ongoing preparedness efforts.
The World Health Organization (WHO) will continue to enhance surveillance in both animal and human populations, collaborate with partners, thoroughly investigate each zoonotic infection, bolster pandemic preparedness planning, and improve readiness for future influenza pandemics.
Here’s a summary of notable avian influenza outbreaks reported to WHO in 2023:
Ecuador
- WHO was informed on 9 January 2023, of a human infection caused by avian influenza A(H5) virus. The case involved a nine-year-old girl from Bolívar, Ecuador, who had recent contact with backyard poultry. She was hospitalized and receiving treatment as of 18 January. This marked the first reported case of human infection with avian influenza A(H5) virus in Latin America and the Caribbean.
Cambodia
- On 23 February 2023, WHO reported a confirmed case of human infection with avian influenza A(H5N1) virus in an 11-year-old girl from Prey Veng province. Tragically, the patient passed away. Investigations revealed the virus belonged to clade 2.3.2.1c, similar to strains circulating in Southeast Asia since 2014.
Chile
- On 29 March 2023, WHO confirmed a case of human infection with avian influenza A(H5) virus in a 53-year-old male from the Antofagasta region of Chile. This marked Chile’s first human case and the third in the Americas. Investigations suggested transmission likely occurred through environmental exposure to infected sea mammals or wild birds.
China
- WHO reported a case of human infection with avian influenza A(H3N8) virus on 27 March 2023. The patient, a 56-year-old female from Guangdong province, had a history of exposure to live poultry and wild birds. She succumbed to severe pneumonia. This was the third reported case of human infection with avian influenza A(H3N8) virus in China.
United Kingdom
- Avian influenza A(H5) virus was detected in a poultry worker in England in mid-May. Another case was reported in a worker involved in culling operations. Both cases were asymptomatic and detected during enhanced surveillance efforts.
Cambodia (November)
- Between 24 and 25 November 2023, WHO reported two cases of human infection with influenza A(H5N1) from Kampot Province. One case resulted in death, while the other was hospitalized. Both cases had exposure to sick backyard birds. Six cases of influenza A(H5N1) were reported from Cambodia in 2023.
These outbreaks underscore the ongoing threat posed by avian influenza and highlight the importance of continued vigilance and preparedness efforts on a global scale.
