India has identified its first human case of bird flu in five years, according to the World Health Organization (WHO). This infection which is caused by the avian influenza H9N2 virus was detected in a child in West Bengal, on Tuesday. This is the second human infection with bird flu reported by India to the WHO, with the first case occurring in 2019.
The child’s health ordeal began with symptoms including fever, abdominal pain, and seizures, prompting an initial visit to a paediatrician. As the condition worsened, with severe respiratory distress and recurring high fever, the child was admitted to the intensive care unit (ICU) of a local hospital. Despite being discharged at the end of February, the child’s respiratory issues persisted, leading to a readmission on the third of March. A swab sample sent to the National Institute of Virology confirmed the presence of the H9N2 virus.
After receiving treatment, including oxygen support, the child was finally discharged on May the first. Fortunately, there were no reports of respiratory illness amongst the child’s family members or other close contacts, according to the WHO. Despite the recovery, the WHO warned that “further sporadic human cases could occur as this virus is one of the most prevalent avian influenza viruses circulating in poultry in different regions.”
The likely source of the infection was identified as poultry, either at the child’s home or in the surrounding area, which she had been both exposed to. Bird flu has been recognised for over a century. The first recorded outbreak occurred in Italy in the early 1900s, though the disease likely existed much earlier. One of the most notable bird flu viruses, H5N1, was first identified in humans in Hong Kong in 1997. The outbreak led to the culling of over 1.5 million chickens to control the spread.
H5N1 re-emerged in 2003, spreading from Asia to Europe and Africa, causing significant economic losses in the poultry industry and leading to numerous human fatalities. By 2021, H5N1 had caused over 800 confirmed human infections, with a mortality rate of about 60%. Another significant strain, H7N9, was first reported in China in 2013. This virus was less deadly to poultry, making it harder to detect and control. However, it led to over 1,500 human infections, with a mortality rate of around 39%.
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This case underscores the ongoing risk of bird flu transmission from poultry to humans. The WHO has noted that with the virus circulating in poultry populations, sporadic human infections are expected. “Most human cases of infection with H9N2 viruses are exposed through contact with infected poultry or contaminated environments,” the WHO stated in its risk assessment. While human infections with H9N2 are generally mild, some cases, like the one in West Bengal, require hospitalisation. Globally, there have been two reported deaths due to H9N2, but there is no evidence that the virus can transmit from human to human.
In humans, avian influenza generally causes mild upper respiratory tract infections but can occasionally lead to severe illness or even death. Symptoms can include conjunctivitis, gastrointestinal issues, encephalitis, and encephalopathy. The WHO also recently confirmed the death of a Mexican man infected by a previously unreported strain of bird flu, H5N2. The health agency advised the public to avoid unprotected contact with live poultry, high-risk environments such as live animal markets or farms, and surfaces that might be contaminated with poultry droppings.
Bird flu viruses primarily infect birds but can occasionally jump to humans. Transmission usually occurs through direct contact with infected poultry or contaminated environments. The virus can be present in bird droppings, feathers, and respiratory secretions. Markets where live birds are sold, known as wet markets, have been significant hotspots for transmission. The primary danger of bird flu to humans lies in its potential to cause severe respiratory illness and death. Human infections often result in symptoms ranging from mild flu-like symptoms to severe pneumonia, acute respiratory distress syndrome (ARDS), and multi-organ failure.
The high mortality rates associated with some strains, such as H5N1 and H7N9, highlight the serious threat posed by these viruses. Moreover, the possibility of bird flu viruses mutating or reassorting with human influenza viruses raises the spectre of a pandemic. If a highly pathogenic avian influenza virus acquires the ability to transmit easily between humans, it could lead to a global health crisis, given the lack of pre-existing immunity in the human population.
While primarily an animal health issue, the potential for these viruses to infect humans and cause severe illness highlights the need for vigilant surveillance, rapid response to outbreaks, and robust public health strategies to prevent a potential pandemic. As the world continues to grapple with various strains of bird flu, the lessons learned from past outbreaks and cases has been crucial in mitigating future risks and protecting both human and animal health.
