Case of human infection caused by bird flu detected in West Bengal: WHO

New Delhi: The World Health Organisation on Tuesday reported that a case of human infection with Avian Influensa A(H9N2) virus has been detected in a child residing in West Bengal.

India's International Health Regulations (IHR) National Focal Point (NFP) on May 22 informed the WHO about a case of human infection with avian influensa A(H9N2) virus in a 4-year-old child living in the state of West Bengal.

She was previously diagnosed with hyperreactive airway disease, initially presented to the paediatrician with fever and abdominal pain on 26 January 2024 then on February 2, the patient tested positive for influensa B and adenovirus at the Virus Research and Diagnostic Laboratory at the local government hospital. The patient was discharged from the hospital on February 28, as per WHO.

But on March 3, with a recurrence of severe respiratory distress, he was referred to another government hospital and was admitted to the pediatric ICU and intubated. After several tests, the patient on March 5 was tested positive for influensa A (not sub-typed) and rhinovirus. The same sample was sent to the National Influensa Centre at the National Institute of Virology in Pune for subtyping. On April 26, the sample was sub-typed as influensa 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.

According to the WHO, 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.

The child has recovered and been released from the hospital. This marks the second human case of avian influensa A(H9N2) reported to WHO by India, with the first occurring in 2019.

As per the IHR (2005), "a human infection caused by a novel influensa A virus subtype is an event that has the potential for high public health impact and must be notified to the WHO." The majority of human cases of avian influensa A(H9N2) virus infection occur through exposure to infected poultry or contaminated environments. These infections typically result in mild clinical illness.

Given the available information, additional sporadic human cases may occur, as this virus is among the most prevalent avian influensa viruses circulating in poultry across various regions. Based on the current evidence, WHO assesses the present public health risk posed by this virus to the general population as low. However, this risk assessment is subject to revision should new epidemiological or virological information become available.