A recent bird flu death has sparked fears that a “brand-new virus” could potentially mutate under the right conditions and lead to a “global pandemic”.
Last week, the Louisiana Department of Health announced that the US had suffered its first bird-flu related death. A 65-year-old patient contracted the H5N1 strain, a highly pathogenic avian influenza, and died several weeks after being admitted to hospital.
The patient had underlying health issues and a subsequent investigation found no other cases or evidence of human-to-human transmission, yet other notable human cases have recently been recorded.
In November 2024, a 13-year-old in Canada was hospitalised after contracting the same D1.1 genotype as the Louisiana patient, while another person was also treated for bird flu in Missouri in September last year.
It comes amid reports of a separate genotype, B3.13, infecting dairy cows in the US, with California officials declaring a state of emergency to “streamline the state’s response to cases”.
Bobbi Pritt, a professor of laboratory medicine and pathology at Mayo Clinic in Rochester, Minnesota, outlined the worrying potential outcomes of the virus mutating and gaining the ability to “efficiently spread from person to person”.
When asked how dangerous it would be to humans, she said: “If the virus were to mutate and gain the ability to efficiently spread from person to person, then this could result in a large outbreak, or even a global pandemic.
“It is because of this concern that the US government is closely monitoring the situation, promptly testing and quarantining infected animals, destroying the milk from any infected dairy cows, and working on a vaccine for livestock.”
However, the conditions required for human-to-human transmission may be inevitable if the “continued circulation” of bird flu in large numbers of animals and the “continued transmission” to humans occurs. Professor Pritt admitted that she felt “nervous” about the number of different types of animals being infected.
She said: “The continued circulation of bird flu in a large number of animals and continued transmission to humans increases the likelihood that mutations may occur that make the virus more adapted to humans.
“This is because RNA viruses such as influenza virus can make frequent mistakes as they replicate, resulting in mutations in the RNA sequences. The greater the number of infected animals and people, the larger the number of replicating viruses, and the greater the likelihood that a mutation could occur.”
Professor Pritt highlighted recent research that indicated that “even just a single mutation” may allow bird flu to pass “efficiently between people”, with the virus found in the Canadian teenager showing mutations that made the virus “more adapted” to human infection.
She said the mutations are believed to have occurred due to “viral replication”, but the virus did not pass to anyone else. Yet, Professor Pritt also indicated that the number of infected animals has risen.
When asked if we’re seeing higher numbers of infected animals than previous years, Professor Pritt said: “Yes, what sets this current outbreak apart from past outbreaks of avian influenza is the high number of infected animals and the large number of different types of animals being infected.
“Pigs, in particular, present a large potential risk as they can be infected with both human and bird influenza strains, and this may allow the viruses to mix and swap genes if they infect the same cell at the same time. This mixing of gene segments could potentially produce a brand-new virus capable of infecting humans.”
Individuals who contracted bird flu via exposure to dairy cows due to the B3.13 genotype have mostly displayed mild symptoms such as conjunctivitis and coughing. Some people infected with B3.13 have had severe symptoms like pneumonia.
Professor Pritt explained that D1.1, which has been circulating in wild birds, has generated “concern” that infection may lead to more severe diseases, but it’s “difficult to draw any conclusions at this time”.
The NHS says a number of different bird flu strains have caused concern over the years, including H5N1, H7N9, H5N6, and H5N8, with H5N8 found to have infected people in Russia back in February 2021.
H5N8 and H5N1 have both been found in birds in the UK, including poultry, captive and wild birds, while H5N6 has also been discovered in wild birds, although this is different to the H5N6 contracted by people in China.
Symptoms of bird flu include high temperature, feeling hot or shivery, aching, headaches, coughing or shortness of breath. Other signs could include sickness, stomach and chest pain, diarrhoea, conjunctivitis and bleeding from your nose or gums.
You can learn more about bird flu via the NHS website here.
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