A WHO DON: Avian Influenza A (H9N2)- India. Excerpt:
Situation at a glance
On 22 May 2024, the International Health Regulations (IHR) National Focal Point (NFP) for India reported to WHO a case of human infection with avian influenza A(H9N2) virus detected in a child resident of West Bengal state in India. This is the second human infection of avian influenza A(H9N2) notified to WHO from India, with the first in 2019. The child has recovered and was discharged from hospital.
According to the IHR (2005), a human infection caused by a novel influenza A virus subtype is an event that has the potential for high public health impact and must be notified to the WHO. Most human cases of infection with avian influenza A(H9N2) viruses are exposed to the virus through contact with infected poultry or contaminated environments. Human infection tends to result in mild clinical illness.
Based on available information, further sporadic human cases could occur as this virus is one of the most prevalent avian influenza viruses circulating in poultry in different regions. With the currently available evidence, WHO assesses the current public health risk to the general population posed by this virus as low.
However, the risk assessment will be reviewed should further epidemiological or virological information become available.
Description of the situation
On 22 May 2024, WHO received a notification from the IHR NFP regarding a human case of avian influenza A(H9N2) virus infection in West Bengal state, India.
The patient is a 4-year-old child residing in West Bengal state. The case, previously diagnosed with hyperreactive airway disease, initially presented to the paediatrician with fever and abdominal pain on 26 January 2024. On 29 January, the patient developed seizures and was brought to the same paediatrician. On 1 February, the patient was admitted to the pediatric intensive care unit (ICU) of a local hospital due to the persistence of severe respiratory distress, recurrent high-grade fever and abdominal cramps. The patient was diagnosed with post-infectious bronchiolitis caused by viral pneumonia.
On 2 February, the patient tested positive for influenza B and adenovirus at the Virus Research and Diagnostic Laboratory at the local government hospital. The patient was discharged from the hospital on 28 February 2024. On 3 March, with a recurrence of severe respiratory distress, he was referred to another government hospital and was admitted to the pediatric ICU and intubated.
On 5 March, a nasopharyngeal swab was sent to the Kolkata Virus Research and Diagnostic Laboratory and tested positive for influenza A (not sub-typed) and rhinovirus. The same sample was sent to the National Influenza Centre at the National Institute of Virology in Pune for subtyping. On 26 April, the sample was sub-typed as influenza A(H9N2) through a real-time polymerase chain reaction. On 1 May, the patient was discharged from the hospital with oxygen support.
Information on the vaccination status and details of antiviral treatment were not available at the time of reporting. The patient had exposure to poultry at home and in the surroundings. There were no known persons reporting symptoms of respiratory illness in the family, the neighbourhood, or among healthcare workers at health facilities attended by the case at the time of reporting.
This is the second human infection of avian influenza A(H9N2) virus infection notified to WHO from India, with the first in 2019. Further sporadic human cases could occur as this virus is one of the most prevalent avian influenza viruses circulating in poultry in different regions.
