Scientists are concerned about the unanticipated emergence of bird flu spreading across US cow herds. Although there isn't any proof that the virus may spread to humans, officials are closely monitoring the issue. How concerned should we be about the H5N1 virus, and what do we know about it?

What is bird flu?

Major strain of H5N1 virus spreading among wild birds globally. It originated in late 1990s China. Bird migration causes domestic and wild bird epidemics. Humans have seldom contracted the virus. Scientists describe the danger to people as minimal. No prolonged human-to-human transmission from birds has occurred. No one knows whether bird flu will cause a pandemic, but specialists are tracking its spread and evolution. H5N1 is growing swiftly in US dairy cow herds in a «ongoing multi-state outbreak» according to the CDC.

The virus's spread to cattle surprised experts, who assumed cows were immune. Among other unexpected developments: The first human case of H5N2 bird flu occurred in Mexico in early June, killing a 59-year-old male. There have been incidents in Mexican poultry farms, but how he acquired it is unknown. Bird flu poses a modest public health risk, according to the WHO and CDC. But experts warn we must monitor the virus's spread. «This case is one more in a series of developments that collectively could be considered a red flag», - says Oxford Pandemic Sciences Institute head Professor Sir Peter Horby. With H5N1 spreading across all continents, experts have been watching it for years. Thousands of poultry and wild bird outbreaks have occurred. In mink farms, epidemics have occurred.

Scientists believe the virus killed around 5,000 sea lions in Peru in late 2023 due to direct contact with infected wild birds. The virus has been found in foxes, bears, otters, raccoons, cats, dogs, goats, and others. «We've been watching it with concern because it's a virus on the march», - says Dr. Ed Hutchinson, Senior Lecturer, MRC-University of Glasgow Centre for Virus Research. Flu viruses may change form and acquire genes as they leave their host. Scientists are looking for indicators H5N1 might spread beyond poultry and wild birds.

Moving to cows

Dr. Hutchinson says cow virus discovery was «a real shock». «When it turns up in an animal where large numbers of them are farmed and therefore in close proximity with humans that immediately is a reason for paying close attention to it». Scientists believe the transmission channel is «artificial» - cows are not touching one other or sharing airborne particles. Instead, they believe milking parlours transmit everything. This is likely due to contaminated milking equipment, according to Dr. Thomas Peacock of the Pirbright Institute. The virus cannot transmit spontaneously between animals at this time. Dr. Peacock thinks the longer it spreads across dairy cows, the more likely it will adapt to do so. About 5% of Americans drink raw, unpasteurized milk, even though pasteurization kills the virus. Canadian scientists are testing milk too.

Can bird flu infect humans?

Humans have caught H5N1 from ill animals in Cambodia, Chile, China, Vietnam, Australia, USA, and the UK. About half of the few hundred cases recorded since 1997 have perished. Recently, US dairy workers with modest symptoms have been reported. Farm workers are getting safety gear and eyewear in several US states. No evidence suggests the virus has evolved into a human hazard, say experts. However, two leading flu scientists cautioned in the British Medical Journal that «the hazard and risk of a major outbreak of H5N1 are large, plausible and imminent». Virologist Tom Peacock thinks the more it spreads throughout the US, the more likely people may get it. Importantly, it's more likely to enter ducks and geese. «That's what we're worried about», - he tells. «Those birds are highly vulnerable to this and tend to transport it long distances».

Bird flu—what can we do?

Some nations are considering vaccination deployment or supply. Any vaccination campaign would deliver doses to poultry farmers, veterinarians, virus researchers, and fur farm workers who handle mink and fox due to restricted supplies. We are well-prepared to create new bird flu vaccines, according to Royal Veterinary College scientist Dr. Jayna Raghwani. «We don't have to start from scratch with an influenza virus», - she adds. «And we have a good understanding of how those [existing flu vaccines] work in order to raise an immune response and be protective. «The virus would be monitored more near farms in an ideal world, she said. «We could do more general monitoring of wildlife close to places we know outbreaks are occurring and more in domestic animals», Raghwani adds, «to better understand how the virus changes between species». «I don't want to downplay concerns about the influenza [circulating in cows]», - he adds. «But if I was talking to my mum or my grandma about the risk to humans, I would say 'don't worry'». «Dr. Hutchinson: It's not February 2020, but we must pay attention. This has dangers and may not go anywhere, but we'd be crazy not to pay attention».