Health
Scientists show cows spread H5N1 bird flu to us through milk – why that matters as pandemic fears grow
Topline
Scientists have proven how cows spread the H5N1 bird flu across the country, infecting other cows, wild birds and even mammals like cats and raccoons. This is evident from research published in Nature Wednesday. As outbreaks on poultry and dairy farms raise concerns, the virus could cause a pandemic in humans.
Cows spread bird flu in the US, researchers have discovered.
Key facts
Using genomic data, computer modeling and data on the spread of the virus, researchers at Cornell University have shown how infected cows from Texas spread H5N1 bird flu to a farm of healthy cows in Ohio, as well as to cats, a raccoon and wild birds . in the area.
It’s one of the first times scientists have seen “evidence of efficient and sustained mammal-to-mammal transmission” of the H5N1 bird flu, said Diego Diel, an associate professor of virology at Cornell and one of the study leaders. authors.
Although it mainly infects birds, so-called highly pathogenic bird flu is capable of infecting mammals, including humans. Diel said repeated spread from birds to mammals or transmission between mammals increases the risk of the virus mutating in a way that “could lead to adaptation to mammals in the future, spillover to humans and potential efficient transmission to humans.”
This H5N1 strain is particularly able to target and infect cells of the mammary gland, a specialized milk-producing gland unique to humans and other mammals, the researchers found, and milk from infected animals contained high amounts of the virus.
Genetic data showed that the infected cows transmitted the virus to cats and a raccoon found dead on the affected farms, likely from drinking raw milk from infected cows, as well as to wild birds, which researchers suspect were infected by environmental pollution or by aerosols created during milking. or cleaning.
Although the data showed clear evidence of mammal-to-mammal transmission, genetic analysis revealed no signs that would lead to greater transmissibility in humans, Diel said. Although he said it is crucial to continue monitoring the outbreak for signs of what the virus is adapting to. mammals.
How concerned should we be about a human bird flu pandemic?
Before COVID-19, experts widely believed that a flu virus would be responsible for the next human pandemic. Four flu pandemics have occurred since 1900, including the 1918 Spanish flu, and seasonal variations of the virus still persist. sicken and kill millions of people per year. Influenza viruses are expert shapeshifters, constantly mutating in ways that help them evade our body’s defenses and survive the drugs we may have developed to combat them. It can also help them acquire different ways to infect existing hosts, as well as find new ones. This is why we need seasonal shots to protect against new circulating variants and why experts worry about even bigger shifts that could trigger a pandemic. H5N1 has long been a concern for health officials, and agencies such as the World Health Organization and the Centers for Disease Control and Prevention have labeled it a pathogen with pandemic potential. Although the disease has only sporadically infected humans, usually after close contact with infected animals, this is still the case infected more than 800 people since 1996.
How bad is the bird flu outbreak in the US?
Although it has been tearing apart wild and domestic bird populations for years, experts believe the increasing spillover to mammals in recent years is of great concern.enormous concernScientists were concerned about outbreaks in marine animals such as seals and sea lions, and the virus has been found in a wide range of mammals, including dolphins, mink, dogs, goats, squirrels and polar bears. Outbreaks among livestock in the US marked a particularly worrying turning point and have increased concerns. The type of virus not documented previously in cows and it shocked many scientists who didn’t think the animals were susceptible to it. However, much remains unknown about the outbreak – experts have criticized Officials’ inability to share crucial information and lax testing requirements, which they say risks outbreaks going undetected – and genetic data is divided scientists wonder if H5N1 is adapting to better infect humans. The intensive nature of livestock farming raises concerns that the virus could gain a foothold in mammals beyond bird populations, and spread the virus to people who work with them and consume products such as milk and beef. Officials emphasize that the risk to humans from bird flu is low and that monitoring for the virus on farms and in milk has been stepped up to look for signs that the virus may be adapting to mammals such as humans as hosts.
What to pay attention to
The federal government has a stockpile of potentially effective vaccines to prevent a pandemic bird flu, but is calling on the industry to develop more vaccines that target circulating H5N1. Moderna received $176 million in federal funding in July to develop an mRNA bird flu vaccine in preparation for a human pandemic. GSK is also developing an mRNA vaccine against bird flu after acquiring the product from German biotech company CureVac.
Large number
11. That’s the number of cases of H5 bird flu in people in the US during the current outbreak that started in 2022, according to the CDC. H5 is a broader category of viruses and these infections are all thought to be the type of H5N1 circulating in animals, although only five have been confirmed as such. All infections followed close interactions with suspected infected animals, the CDC said, with four following exposure to dairy cows and seven to poultry. In that time, more than 100 million domestic birds, at least 9,555 wild birds and 168 dairy herds have been affected. Hawaii is the only US state with no confirmed H5N1 infection in wild birds, poultry or animals.
Tangent
A man in Mexico died in June after contracting a new strain of bird flu, H5N2. It was the first time the virus, other than H5N1 virus spread among livestock, had been seen in humans and raised more questions about bird flu’s ability to reach humans. The WHO said the man had no history of exposure to poultry or other animals and it is not clear where the man may have been exposed to the virus. The agency said the risk from H5N2 is low and no further cases have been reported after investigation.
Read further
Receive text alerts from Forbes Breaking News: We’re launching text alerts so you’re always up to date on the top stories driving the day’s headlines. Text “Alerts” to (201) 335-0739 or Log In here.
