by British scientists are closely monitoring the bird flu outbreak in the United States after the H5N1 virus infected more than 30 cattle herds across dozens of states.
One person is infected after coming into contact with a cow.
Currently, cows in the UK are not being tested for bird flu, with scientists from the Department for Environment, Food and Rural Affairs (Defra) monitoring the situation in the US.
The virus is believed to have been circulating in the US for weeks, with tests showing traces of the virus in one in five US commercial milk samples, suggesting the outbreak is more widespread than previously thought. this.
What is happening in the USA?
The American Center for Disease Control (CDC) says there is an outbreak in nine states, affecting 34 dairy herds.
Traces of the bird flu virus are widely found in milk sold in the US but there is no risk to people from drinking pasteurized milk, authorities said. Their investigation found that the pasteurization process successfully killed the virus, which meant it was not infectious.
US officials have warned against drinking ‘raw’ (unpasteurized) milk.
One person, a farm worker from Texas, has been confirmed to have bird flu and conjunctivitis (an eye infection) in the current outbreak after exposure to dairy cows.
The CDC said: “This is the first time these bird flu viruses have been found in cattle. CDC has confirmed one human HPAI A(H5N1) infection that had exposure to dairy cattle in Texas that were thought to be infected with the virus.
“Although thought to be rare, this exposure to the HPAI A(H5N1) avian influenza virus is the first likely instance of mammalian transmission to humans.”
What does it mean for the UK?
Cows in Britain are not currently being tested for bird flu.
DEFRA has said that there is currently no evidence of the virus spreading among cattle in the UK, but that they are closely monitoring the US outbreak.
He said the virus is different from the H5N1 virus circulating in the UK and Europe and the likelihood of an identical virus emerging in UK cattle was “highly unlikely”.
He warns that the most likely route for the US H5N1 virus to enter the UK is through trade in beef products from US farms, or from migratory wild birds. However, Defra has said that this risk of introducing birds is “very low” and that there is no trade in live cattle, adding: “There is no evidence that this [introducing of the virus to the UK] occurred based on genomic analysis of outbreaks in Great Britain.”
The United States is approved for the importation of raw milk. Although there is not thought to be any risk to humans from drinking pasteurized milk, the CDC states that “people with close, prolonged, or unprotected exposure… to unpasteurized (“raw”) milk… are at increased risk of infection.”
UK officials have taken no action to restrict the import of products of animal origin from the US, according to officials.
Scientists at the UK’s Health Security Agency and Defra have urged farmers to be “cautious” too.
A situation assessment published by Defra on April 25 said: “All dairy keepers should remain vigilant and ensure that any visitors to their premises have not had any recent contact with cattle or dairy cattle premises in regions where in question.
“People working on farms or with animals returning from any affected areas should avoid any contact with domestic cattle or poultry on commercial and small holdings.”
Why are people worried?
Experts are concerned that the virus could evolve to be able to spread between people.
Scientists at the United Nations have described the ongoing H5N1 bird flu infections as a “significant public health concern”, but point out that no human-to-human transmission of H5N1 has yet been recorded.
Dr Jeremy Farrar, Chief Scientist at the World Health Organization (WHO) said bird flu has an ‘extremely high’ mortality rate in humans. Farrar said H5N1 has spread from poultry and ducks to animals such as dairy cows.
Both the CDC and the UKHSA say the risk to the public remains low, but Farrar has warned that the emerging virus is ‘of great concern’ to be able to spread from person to person.
Farrar said health authorities “need to make sure that if H5N1 were to come across humans with human-to-human transmission, we would be able to respond immediately with equitable access to vaccines, therapeutics and diagnostics.”
Is the virus changing?
The virus in the human case is very different from the bird flu virus samples taken from infected cattle by government officials last weekend, said Dr. Michael Worobey, an evolutionary biologist from the University of Arizona.
The difference between the genetic sequences of the worker’s virus and the other 239 samples provided shows that “it was a widespread epidemic for a long time”.
A CDC spokesman said there are “always some subtle changes in genetic sequences when flu viruses move from host to host,” but added that the data points to the virus evolving from birds to infect and then transmit to cattle to the person.
