Update on H5N1: WHO

Despite concerns, current public health risk posed by avian influenza A (H5N1) deemed low by WHO

While there is a risk of the H5N1 avian flu virus spreading to cows in countries other than the United States via migratory birds, the overall public health risk posed by the H5N1 virus is currently “low," the U.N. World Health Agency (WHO) said on Tuesday.

"We assessed the current overall public health risk posed by the H5N1 to be low,” said Dr. Wenqing Zhang, Head of WHO’s Global Influenza Programme, during a news briefing at the United Nations in Geneva.

“For those exposed to infected birds or animals or contaminated environments, the risk of infection is considered low to moderate. It's important to note that influenza viruses evolve, posing ongoing risks,” Dr. Zhang added. Dr. Zhang highlighted the unique aspect of the current situation, saying that “this was the first time that the virus was detected in calves, in the past this virus was detected in birds. And, of course, since last year, this virus was also detected in certain mammals.”

As the virus is carried around the world by migratory birds, "there is certainly a risk that cows from other countries could be infected," the WHO official said. While the virus has been detected in dairy cattle in the U.S., Dr. Zhang stressed the need to ascertain whether cow-to-cow transmission has occurred.

There are “many migratory birds, so they are traveling around the world and carrying viruses”, Dr. Zhang explained. “Certainly, there is a risk also spreading the virus to other regions itself. And also, because at the moment it is not clear how actually cow-to-cow, or whether there is cow-to-cow transmission, and how the virus is being transmitted among cows, so there are lot uncertainties.”

“At the moment the H5N1 virus we talked about are detected in dairy cattle in the U.S and only in the U.S.. As of 24th April, the virus was detected in cattle in eight states,” said Dr. Zhang. “I think the figure has slightly increased in the past one week.”

Based on available studies conducted in the United States, virus fragments found in pasteurized milk are not infectious, WHO said, noting that ongoing sampling suggests that raw milk from infected cows may contain live viruses, which may pose a threat, especially to farm workers. Reports so far suggest mild symptoms in one person working on an affected dairy farm in the U.S., who contracted the virus.

U.S. authorities believe that milk sold in stores is "safe" and that pasteurization kills the virus in the milk.. “Those contained in the milk are only virus particles, it is inactivated. There is no infectious power of those materials contained in milk. So it is less likely that the virus will be able to spread through milk itself, based on the information so far,” according to Dr. Zhang.

WHO emphasized the importance of surveillance and information sharing to combat the spread of zoonotic viruses, particularly among agricultural workers. “Surveillance is working,” Dr. Zhang said, emphasising that health authorities in the United States are regularly providing updated information on the evolution of the virus to the global health agency.

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Update on H5N1: WHO

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