13 avril 2023
While the WHO revealed on Tuesday the first death due to the H3N8 avian flu, should we be worried about the spread of the virus to humans? We take stock of this subtype of influenza A, observed for the first time in the early 2000s, in the United States.
A 56-year-old woman died in China from the H3N8 virus. This is the first known human victim of this avian flu subtype. According to the press release from the World Health Organization (WHO), published on Tuesday April 11, the patient, a resident of Guangdong province, had been ill since February 22, 2023. Hospitalized on March 3, she died on March 16. .
Still according to the WHO, two other cases of human contamination by the H3N8 subtype are known, recorded in April and May 2022, also in China.
What is the H3N8 avian flu?
Avian influenza is an infection caused by type A viruses. It is a disease which particularly affects birds, but also certain mammals, and which is particularly virulent and deadly in poultry farms.
The H3N8 virus, a subtype of influenza A, was first detected in dog and horse populations in the United States in the early 2000s. It was also found in seals, which died of pneumonia, also in the USA (New England), in 2011. “The H3N8 virus is often detected in animals. This is the most common virus subtype seen in birds,” explains the WHO.
What are the symptoms of H3N8 avian flu?
Human infection with avian virus can be asymptomatic or cause disease. The patient who died in China died of severe pneumonia.
“Depending on factors related to the affected subtype and the infected individual, symptoms can range from conjunctivitis to other mild symptoms such as flu-like illness, severe acute respiratory illness and sometimes, death”lists the WHO.
What are the risks for humans?
For the time being, no case of human-to-human transmission is known for this virus subtype. For all avian influenza viruses, only “very rare cases of human-to-human transmission of the H5N1 virus” were observed, “remained episodic”, notes the Pasteur Institute. Present in Asia and pathogenic for humans, the H5N1 virus has succeeded many times in crossing the species barrier.
The three Chinese cases of the H3N8 virus were all exposed, directly or indirectly, to infected poultry, reports the WHO. Regarding the deceased patient, she had been exposed to poultry and the presence of wild birds near her home. The health authority thus expects the occurrence of other human cases, sporadic, linked to the exposure of certain populations to contaminated poultry.
According to the WHO, the H3N8 virus does not have the possibility of being transmitted easily and durably between humans. It considers the risk of human-to-human spread of the disease to be low. But the proliferation of zoonoses and the strong presence in the world of avian influenza viruses, which are constantly evolving, require increased monitoring of human and animal populations, pleads the Organization. Objective: to prevent a mutation that would allow human-to-human transmission.
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Source : WHO, Pasteur Institute
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Written by : Dorothée Duchemin – Edited by Vincent Roche