Millions of birds have been killed or culled since October 2021 due to the outbreak of avian influenza. While the deadly H5N1 virus has affected humans, the cases have been rare and there is no proof of people-to-people transmission yet. But could that change soon?
The recent cases of avian influenza, better known as bird flu, in mammals have evoked worry across the globe over its possible threat to humans.
While the World Health Organization (WHO) has assured that the risk to humans remains low, Director-General Tedros Adhanom Ghebreyesus said on Wednesday (8 February) that the infections reported in mammals such as mink, otters and sealions “need to be monitored closely”.
He also said that “we must be prepared for any change in the status quo”, urging people not to touch dead or sick wild animals, reported Reuters.
The current bird flu outbreak has already killed 15 million domestic birds, while 193 million others have been culled since October 2021, noted Al Jazeera.
What is avian flu and why is its recent outbreak worrying scientists? Can bird flu spur the next pandemic? Let’s find out.
Avian flu is a disease in birds triggered by infection with avian influenza Type A viruses, as per US Centers for Disease Control and Prevention (CDC).
These are highly contagious viruses found in saliva, nasal secretions, and feces of the infected birds.
Its deadly H5N1 strain is of particular concern, which according to the WHO, has had a 53 per cent mortality in the rare cases witnessed in humans, reported Al Jazeera.
H5N1 was first detected in domestic waterfowl in China in 1996. It then spread to migratory birds around 2005, noted Smithsonian Magazine.
As per the journal Science, these migratory birds have transmitted the virus across the globe.
The virus has jumped from Europe and Asia to North America, spreading to birds in South and Central America, as per Al Jazeera.
The ongoing bird flu outbreak is the largest in Europe so far, according to the European Food Safety Authority.
The current outbreak has also been touted as the worst in history of the United States, with the virus directly or indirectly causing 58 million bird deaths in the past year, reported Fortune.
The avian flu spread has also affected large populations of wild birds across the United Kingdom. The Guardian reported citing ornithologists that wild birds coming to Britain in the spring could set off new outbreaks.
Around 16,000 barnacle geese perished on the Solway Firth last winter, while 1,500 great skuas were found dead on the island of Foula, in Shetland.
Over 13,000 birds, mainly pelicans, died on Peruvian coasts last year following an outbreak of avian influenza. Peru also had to cull 37,000 birds on a chicken farm over the risk of bird flu, AFP reported.
At least 28 out of around 3,000 penguins in a colony at Cape Town’s Boulders beach in South Africa have been killed by bird flu since last August, as per a Reuters report.
Jump to mammals
Avian flu is not only limited to birds but is also spilling over to mammals.
Peru said in early February that along with 55,000 wild birds, avian flu has killed 585 sea lions, reported AFP.
The US Department of Agriculture has confirmed avian flu cases in mammals such as skunks, a raccoon and a red fox.
The virus has also been detected in foxes and otters in Britain, a cat in France, and grizzly bears in the US state of Montana. As per AFP, these mammals were suspected to have consumed infected birds.
The eight foxes and otters which tested positive for avian flu in the UK last year had a PB2 mutation, reported AFP.
This PB2 mutation was also detected in the H1N1 swine flu strain that was behind the 2009 pandemic, which killed between 1,23,000 to 2,03,000 people globally, noted Al Jazeera.
“The mutation is a signal that this virus is trying to cross the barrier between species and adapt to the mammalian population,” Wenqing Zhang, the head of the WHO global influenza programme, told Al Jazeera.
Last October, a bird flu outbreak led to culling of over 50,000 mink on a farm in Galicia in northwestern Spain. This was a rare case where it is believed that the mammals spread the disease to each other, rather than contracting it through an infected bird.
On the mink farm outbreak, Tom Peacock, a virologist at Imperial College London, told Science, “This is a clear mechanism for a H5 pandemic to start.”
On the ongoing outbreak, Peacock told AFP, “We are not fully sure why it’s happening now but we think this might be driven by a slightly different strain of H5N1 which is spreading very effectively in wild, migratory birds”.
“Until this particular outbreak, all mammalian infections could be attributed to direct contact with virus-contaminated material,” Hualan Chen, a virologist at the Harbin Veterinary Research Institute in China, told Nature.
Chen added that its transmission between mammals “implies that this H5N1 virus may pose a higher risk to public health”.
Is this a premonition of a new pandemic?
While cases of avian flu in humans have been few, many have proved deadly.
According to the WHO, there have been a total of 868 cases of H5N1 in humans between January 2003 and November 2022, out of which 457 were fatal.
In January, the WHO said avian flu has infected a young girl in Ecuador, Latin America’s first such case. Since last year, there have been five human bird flu cases, reported Al Jazeera.
However, as per WHO, there is no evidence of bird flu being spread from one human to another so far.
Experts have also assured that the threat of an H5N1 pandemic is not “currently high”. But, sooner or later, “there will be another influenza pandemic,” Zhang was quoted as saying by Al Jazeera. If avian influenza spurs that pandemic, the results would be big.
Rajiv Chowdhury, senior epidemiologist and professor of global health at Florida International University, told Fortune, that if there is a human-to-human transmission of the H5N1 virus “the potential impact could be significant”, which could be a signal of the beginning of a “new global influenza pandemic.”
Zhang also noted The drawback of rare cases of avian flu in humans means there is a “complete lack of immunity”. “So if the virus did evolve a way to reliably transmit from animals to humans, or worse yet, between humans, it would almost certainly mean a pandemic,” Al Jazeera reported.
With inputs from agencies
This article originally appeared on https://www.firstpost.com/ and was reproduced here with permission