The bird flu virus was in US livestock for months without being detected


The H5N1 strain of bird flu has spread rapidly among mammals in the United States. The first death of a common dolphin due to the virus has been documented and the number of infected cows could be higher than estimated. by Fernanda Gonzalez

The H5N1 strain of bird flu has been spreading silently in American livestock for months. JUSTIN SULLIVAN/GETTY IMAGES

The H5N1 strain of bird flu has been spreading silently in American livestock for months. This suggests that the number of cows and areas affected by the virus could be larger than previously estimated, according to a new preliminary analysis based on data provided by the United States Department of Agriculture (USDA).

The variant studied has been linked to human infections, the death of a polar bear in Alaska and the death of a dolphin off the coast of Florida. International health authorities such as the World Health Organization warn that the rapid spread of avian influenza among various mammal species could accelerate the evolution of the virus. It is feared that it will mutate to be spread from person to person, a situation that has not happened so far.

The H5N1 strain of bird flu has been spreading silently in American livestock for months. JUSTIN SULLIVAN/GETTY IMAGES

Traces of bird flu found in 20% of milk in US supermarkets, suggesting broader outbreak

Milk is still considered safe for consumption, but infectious disease experts are alarmed by its prevalence.

A group of academics led by Michael Worobey, an evolutionary biologist at the University of Arizona, examined genomic data related to the condition released by the USDA early last week. He concluded that the bird flu outbreak may have started in late December or early January, which “implies prolonged and undetected spread. “It suggests that more cattle across the United States and even in neighboring regions may have been infected.”

US federal authorities reported on March 25 about a strain of highly pathogenic avian flu present in dairy cows in Texas and Kansas. The USDA has confirmed H5N1 infections in 34 dairy herds in nine states since then.

The information released by the agricultural agency does not provide details about the origin and evolution of the infections. The agency's reports were made public almost a month after the appearance of the disease in dairy cows was identified. Tulio de Oliveira, a bioinformatician at Stellenbosch University, explained in a statement reported by Nature magazine that accurate reporting is especially important for fast-spreading respiratory pathogens that have the potential to cause pandemics.

Martha Nelson, a genomic epidemiologist at the National Center for Biotechnology Information, adds that the bird flu variant has had months to evolve. The pathogen has modified “a section of viral protein that is related to a possible adaptation to spread in mammals.”

News date: 2024-04-30

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