A new strain of avian flu has been found to show a low infectious rate but a heightened ability to infect through air as compared to its earlier variants, a study has revealed.
A strain recently extracted from polecat, mink and an infected Texas-based dairy worker in the United States exhibited an increased ability to transmit by air, a study published in the journal Nature Microbiology has concluded.
The virus strain from Texas harboured a mutation named PB2-E627K and another mutation PB2 T271A from polecat and mink were found to be transmissible between ferrets. These findings were noted by researchers from Erasmus University Medical Center in the Netherlands.
Given the ongoing viral epidemic in cattle and the high risk of exposure for farm workers as well as other mammals along with the possibility of milk contamination it is crucial to contain the outbreak effectively, the study noted.
The research studies are being carried out regularly to understand how this virus spreads among cattle, its potential for mammalian adaptation and its capacity for airborne transmission, the study noted.
The scientists experimented with ferrets by exposing them to the virus to assess the public health risk.
Ferrets are known as one of the best animal models for studying influenza in humans because clinical signs of disease and transmission are similar to human beings, the Center for Infectious Disease Research and Policy mentions.
As part of the study, these ferrets were contained in cages and opened to aerosol samples that captured infectious virus suspended in the air.
The scientists experimented with six different viruses including the H1N1 seasonal flu from 2009, an H5N1 wild-type zoonotic traced in Indonesia from 2005 and its modified version that were found earlier transmitted among ferrets.
The samples from 2024 were particularly of clade 2.3.4.4b that has been spreading rapidly among poultry, wild birds, marine and terrestrial mammals which eventually resulted in global epizootic.
In March 2024, the virus was reported to infect dairy cows in the United States and has since spread among 695 dairy herds across 15 states. The virus has also infected 55 humans who were exposed to infected poultry and cattle.
The samples were tested in four ferrets which showed that one in four of the experiential mammals were infected from polecat strain and another from dairy workers in 2022 and 2024 respectively.
They also concluded that the 2005 H5N1 virus from Indonesia never transmitted via air through ferrets.
“Our results indicate that recent A(H5N1) viruses exhibit a low but increased level of infectious virus shedding into the air as compared with older A(H5N1) viruses,” the researchers concluded.
Expressing concerns, they added that the observations show evolution of an A(H5N1) towards mammalian and potential human adaptation.
The scientists further noted, “This aligns with a previous study, which showed that airborne-transmissible viruses exhibit high replication in the upper respiratory tract and fast release in the air compared with non-transmissible viruses that show lower viral RNA levels in air sampled from infected ferrets.”
Meanwhile, the UK has ordered a contract of producing more than five million doses of human H5 influenza vaccine to guard the country in potential H5 influenza pandemic.
A press statement from the UK Health Security Agency (HSA) stated the vaccine will be produced by UK based company CSL Seqirus UK Limited.
“It is important for us to be prepared against a range of different influenza viruses that may pose human health risks,” Meera Chand, Emerging Infection Lead at the UK Health Security Agency, stated in a press statement.