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Avian flu: ‘Strong evidence’ suggests virus first crossed from mammals to humans | Science and technology news

Scientists fear bird flu has spread from mammals to humans for the first time, marking another step in the evolution of the deadly virus.

A new analysis concludes there is “strong evidence” that a Texas farmworker tested positive the H5N1 virus I caught it from sick dairy cows.

Although more people have become infected with the virus in recent years – including some who have died – they all transmitted it from birds.

There is growing concern about the failure of American authorities to contain the spread of the virus.

So far, 36 herds in nine states have tested positive. But milk tests have shown the virus has spread far more widely.

The longer it spreads unchecked in a domesticated mammal, the greater the chance it has of adapting to a new species – and being passed on to people in close contact.

According to the report in the New England Journal of Medicine, the unidentified man’s symptoms were mild. He developed an eye infection, conjunctivitis, but had no fever or difficulty breathing. His lungs were also clear.

He and the people he lived with were given antiviral medications as a precaution. No one else got sick.

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How does bird flu spread?

The team, which included researchers from the Centers for Disease Control, said: “Given that the infected person was a dairy farm worker who had reportedly been in contact with sick, presumed infected cows in Texas and “Had no contact with other mammals or birds, we believe it is genetic.” and epidemiological data provide strong evidence of human infection following contact with presumably virus-infected cows.”

Some mammals infected

The highly pathogenic H5N1 strain was spread worldwide by wild birds.

Initially, it was mainly poultry that were infected, and millions were killed to prevent further spread.

However, there have been some infected mammals, including a small number of foxes, seals and dolphins in the United Kingdom.

There was also suspicion that the virus spread between farmed mink and within sea lion colonies.

But there was a surprise when it appeared in dairy cows in the US, which were suffering from a sharp decline in milk production.

The virus has been spreading for months

There is evidence that the virus has been spreading undetected since the beginning of the year. Some cows are asymptomatic.

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A gray seal lounges on a small island in Casco Bay off Portland, Maine, on Tuesday, September 15, 2020.  Image: AP Photo/Robert F. Bukaty, File
Picture:
Avian influenza has been detected in seals in the United States and the United Kingdom. Image: AP

Scientists believe the man could have been infected either by an airborne virus that got into his eyes in the milking parlor or by a virus on his hands or gloves that was transferred to his eyes.

Although the farmworker only had a mild infection, H5N1 can be serious – and even fatal – to humans.

According to the World Health Organization, 888 people were infected worldwide between 2003 and the end of March this year, with 463 deaths.

Safe for beef and dairy products

US authorities have detected virus fragments, but no active viruses, in pasteurized milk. They say dairy and beef are safe.

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In the United Kingdom, a risk assessment by government scientists has concluded that the risk of a similar outbreak in dairy herds is very low.

They say the animals are kept in different conditions and that the likelihood of cow flu being transmitted from wild birds across the Atlantic is low.

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