Bird flu typically spreads by infecting wild birds and moving along migratory routes, but the virus now prevalent in the United States is about to be carried by plane across the Atlantic.
This category A pathogen, which is now spreading among cows in the United States, is being sent to a high-security laboratory in the United Kingdom so experts can better understand the potential risks to humans and animals.
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Last week, Dr D., a virologist at the UK Animal and Plant Health Agency (Apha) laboratory in Weybridge, Surrey. “It could be shipped at any time,” Ashley Banyard said. “I saw the packing instructions in my email this morning.” It is crucial that this virus does not spread to the wider environment: H5N1 has killed millions of wild birds and thousands of mammals worldwide.
Although bird flu is widespread in the UK, the specific genome imported for testing is the only one known to infect cattle and the only place where this has been recorded is the USA. “We really want to know if there is something special about this emerging genotype,” Banyard said.
A bit like a Russian doll, it is transported in a small amount of liquid in three tubes with dry ice between the layers. It costs a private courier hundreds of pounds to transport it safely from door to door.
The virus made headlines in the US in March after it was detected in dairy cows in Texas and Kansas following widespread reports of loss of milk production. It has since been reported in nine US states and shows no signs of slowing down. It has also been detected in cats and humans and is likely to spread for months before being detected.
“We hope that the situation in America will be controlled and further limited, and we will no longer see this virus in cattle, but you never know,” Banyard said.
Everyone working at the Weybridge lab undergoes counter-terrorism checks and has multiple levels of locked doors and keycards. “I know it sounds like a James Bond kind of thing, but it’s definitely not; they’re just laboratories,” Banyard said.
A variety of mammals, from Spanish mink to polar bears in the Arctic and seals in Antarctica, have been killed by the virus, often by eating infected meat.
The outbreak in the US has caused alarm because it is the first time bird flu has been detected in a cow and it is unclear how it got there. According to the World Health Organization (WHO), the ability of the virus to spread in dairy cattle has led to “great concern” that the virus could spread more easily in humans. Its chief executive said last week that the virus showed no signs of adapting to spread from person to person.
A preliminary evaluation paper published earlier this month is the first to claim that the virus came to dairy cows via a single entry from a wild bird and was transmitted from cow to cow. It is currently believed that milk is the primary vector (possibly via milking equipment) and symptoms such as decreased milk production and loss of appetite are mild.
Dairy cows transported interstate in the US now must be tested for bird flu. Health officials say the milk is safe to drink as long as it has been pasteurized, a process designed to kill bacteria and viruses.
There are concerns that cows could become infected in other countries where testing is not available, but Banyard is confident this has not happened in the UK anyway. “We have had over 380 infected premises across the UK in the last two and a half to three years and we have not seen any evidence of these symptoms in cattle,” he said.
Very few livestock are brought from the US, and it is rare for migratory birds to bring bird flu viruses from the US to Europe because it is not a common migration route. During the three years of this H5N1 epidemic, not a single North American strain was found in Europe. “And everyone in Europe is calling,” said Prof Ian Brown, a virologist at the Pirbright Institute in Surrey.
Brown said it was a surprise to see it show up in dairy cows — “What it tells us is that it can get into areas you wouldn’t expect” — but it marks a new chapter in the evolution of H5N1, and the number continually surprises researchers. the number of animals it can infect (at least 26 mammal species have been infected). “These are the first stages of an epidemiological investigation.”
Scientists need to understand the potential risks of bird flu to humans. “All international eyes are on this,” Brown said. Before the virus can start spreading between people, it needs to make some genetic changes that mean it can replicate in human cells.
Brown said people who work in close contact with dairy cattle should be monitored because they are at the highest risk; More than 200 are being tracked in the United States. “We have to be careful. We have to make sure we can track this so that if the risk changes for people, we can detect it early. That’s very important.”
If bird flu began to spread among humans, this would be a significant concern because the H5N1 virus has a high mortality rate. According to the WHO, from 2003 to 2024, 889 cases were reported in 23 countries, and more than half of these people died. In other words, pre-pandemic vaccines were already stocked.
The virus is already circulating in ways it hasn’t before. Prof Rowland Kao, an epidemiologist at the University of Edinburgh’s Roslin Institute, said: “The fact that we introduce another animal into the mix could potentially change it… which creates another layer of unpredictability.”
This is the first time an influenza A virus has been found in cattle; This virus could create “threats to wildlife, animals and potentially humans that we have not experienced before.”
Monitoring and sharing data, such as the testing of the US genome in UK laboratories, is crucial to staying informed of any potential outbreaks. “We are a long way from the human epidemic,” Kao said. “But this brings things one step closer.”