New Delhi: An outbreak of avian flu that has infected specific dairy cows in at least six US states and a farmworker in Texas has become a cause for worry in the medical world, with some global experts even raising concerns that it could be “getting dangerously close” to triggering a pandemic “100 times worse than COVID-19”.
According to the US Centre for Disease Control (CDC), which sequenced the virus genome from a specimen collected from the patient in Texas, the flu was caused by the highly pathogenic avian influenza A (H5N1) — a virus similar to the HPAI A(H5N1) pathogen infecting cattle, wild birds, and poultry in some parts of the country.
According to the CDC, the Texas patient was the second reported case of the virus in the US. The first was from 2022 when a person in Colorado was “presumed” to be infected after coming in contact with poultry, the agency says on its website.
What is avian flu and is there a need to worry? Here’s everything you need to know about avian flu.
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What is avian flu
The CDC defines avian influenza or bird flu as “the disease caused by infection with avian (bird) influenza (flu) Type A viruses”.
“These viruses naturally spread among wild aquatic birds worldwide and can infect domestic poultry and other bird and animal species,” the website says. “These pathogens do not normally infect humans. However, sporadic human infections with bird flu viruses have occurred.”
According to senior virologist Gagandeep Kang, who’s associated with the department of gastroenterology at the Christian Medical College (CMC) in Vellore, H5N1 cases rarely transmit to humans. However, if they do, its severity can vary widely — from mild conjunctivitis to even death.
India’s only reported case of the H5N1 infection was in 2021 when an 18-year-old man from Haryana died of the infection. Experts, however, believe that the lack of more recorded cases could be due to an absence of thorough surveillance.
“Identification and reporting of types of influenza in India is very limited so we might not know, (of the real number of avian flu infections),” she said.
According to biologist and genome scientist Dr. Vindo Scaria, while bird flu is not a new disease, an emerging new lineage 2.3.4.4b of H5N1 has been spreading across the globe since late 2020, mainly carried by migratory birds following certain routes.
“However, the latest panzootic (the animal equivalent of a pandemic) is huge and has a significant effect on the avian population with disastrous consequences to the ecology and significant economic loss affecting poultry across the world,” Scaria, senior consultant with the Vishwanath Cancer Care Foundation and also associated with the Indian Institute of Technology (IIT, Kanpur), said.
In rare instances, the virus can infect mammals from birds, he said. Several such spillovers have been noticed in recent years — the most recent being polar bears in Antarctica.
“Close contact with infected animals could mean the virus could spill over to humans. This comes with a significantly large fatality rate — over 50 percent,” he said.
The latest outbreak of H5N1 was first detected late last month. First dubbed as a mystery disease, the culprit was later identified by the US Department of Agriculture (USDA) as a highly pathogenic strain of the virus spreading in dairy herds across the states of Texas and Kansas.
The infected animals showed symptoms such as loss of appetite, low-grade fever, and reduced lactation. According to Scaria, this was the first time that H5N1 had been detected in cattle, raising concerns about potential transmission routes and the broader impact on the dairy and meat industry.
Should India be concerned? “Yes and no”, says Scaria. “Yes, because the outbreak in the avian population is quite large and widespread and has possibly resulted in the extinction of many species. And no, because there is no evidence of widespread infections in humans yet.”
Kang, meanwhile, said that while there have been H5N1 outbreaks among birds in India, it’s still unclear if the virus was transmitted through migratory birds or some other mechanism.
However, she said that like in the US, India should conduct surveillance on avian flu, particularly since it’s expected that H7N9 — another subtype of the Influenza A virus — might cause outbreaks in humans, she said.
“In fact, it has already resulted in small outbreaks, mainly in southeast Asia and China, but mutations that increase its ability to spread in humans could change it into a pandemic,” she warned.
Need for surveillance, specific vaccines
According to Dr. Anurag Agarwal, dean of biosciences and health research at Ashoka University’s Trivedi School of Biosciences, there is no need to worry about H5N1 just yet. However, the biologist recommends a nationwide integrated respiratory surveillance system to identify moderate to severe respiratory infections, test for multiple known pathogens, and conduct detailed investigations of unknown cases.
One such integrated system is the global efforts towards One Health — a proposed integrated approach to optimise health outcomes and prevent, predict, and respond to global health threats such as the COVID-19 pandemic.
“I believe that globally, including India, we are already moving towards it. Outbreaks will keep happening. As long as we are adequately prepared, the human costs will be low,” he said.
Experts also insist on global efforts to develop vaccines to help mitigate any future risks. However, Kang worried that in India, influenza vaccines appear to matter little because there is a small internal market.
“This is more of a concern because scaling up flu vaccines made in eggs has a long lead time,” Kang said.
She was referring to the most common way that flu vaccines are made — using an egg-based manufacturing process through which health agencies provide private sector manufacturers with candidate vaccine viruses grown in chicken eggs.
These vaccine viruses are then injected into fertilised chicken eggs and incubated for several days to allow the viruses to replicate. This production method requires large numbers of chicken eggs and could take longer than other production methods.
But this isn’t the only method to make vaccines. According to Kang, making vaccines in cell lines – when the viruses used to make vaccines are grown in mammalian cell cultures — or using other technologies such as protein-based, or mRNA vaccines (such as Pfizer and Moderna Covid ones) require existing platforms and can be easily switched over to.
(Edited by Uttara Ramaswamy)
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