Avian flu spreads to mink on a farm in Spain

Scientists have been keeping an eye on this bird flu virus since the 1950s, although it was not considered a threat to humans until a 1997 outbreak in Hong Kong among visitors to live poultry markets.

As bird flu hits more and different animals, like the mink farm, there are fears that the virus could evolve to spread more easily between people and potentially start a pandemic.

Scientists say another type of avian influenza was likely behind the devastating influenza pandemic of 1918-1919, and avian viruses played a role in other influenza pandemics in 1957, 1968 and 2009.

Still, the risk to the general public is now low, says Dr. Tim Uyeki from the US Centers for Disease Control and Prevention.

A look at the bird flu virus and why it’s receiving renewed attention:

What is bird flu?

Some influenza viruses primarily affect humans, while others primarily affect animals. For example, there is influenza that occurs in dogs, as well as swine or swine flu viruses. And then there are avian viruses that naturally spread to wild waterfowl like ducks and geese, and then to chickens and other domesticated poultry.

The bird flu virus that is attracting attention today – type A H5N1 – was first identified in 1959 by researchers studying an outbreak of flu in chickens in Scotland. Like other viruses, it has evolved over time, creating newer versions of itself.

By 2007, the virus had been found in more than 60 countries. In the US, it has recently been detected in wild birds in all states and in commercial poultry farms or backyard flocks in 47 states. Since the beginning of last year, tens of millions of chickens have died from the virus or been culled to stop the spread of outbreaks, one of the reasons cited for soaring egg prices.

How often do people get bird flu?

The Hong Kong outbreak in 1997 was the first time this bird flu was blamed for a serious human illness. Six of the 18 infected died. To contain the outbreak, the Hong Kong government closed live poultry markets, killing all birds in the markets and halting imports of chickens from southern China. It worked, for a while.

Symptoms are similar to other flus, including cough, body aches and fever. Some people have no noticeable symptoms, but some develop severe ones. life-threatening pneumonia.

Globally, nearly 870 human infections and 457 deaths in 20 countries have been reported to the World Health Organization. But the pace has slowed, and over the past seven years there have been about 170 infections and 50 deaths. In the vast majority of cases, those infected got it directly from infected birds.

The first and only US case occurred just last April. A prison inmate on a work program picked it up while killing infected birds at a poultry farm in western Montrose County, Colorado. His only symptom was fatigue and he recovered.

Can it spread between people?

In some cases, investigators concluded that the bird flu virus appeared to spread from one person to another. This happened in Thailand, Vietnam, Indonesia, China and Pakistan, most recently in 2007.

In each cluster, it spread within families from one sick person in the home. Scientists don’t think it can spread easily through casual contact like seasonal flu can. But viruses mutate and change. Scientists fear that avian flu is becoming increasingly common and mutating with other influenza viruses in infected people or animals, making it easier for it to spread to humans.

It wouldn’t take much to do that, “and then we would be in a really difficult situation,” said Dr. Luis Ostrosky, chief of the Department of Infectious Diseases and Epidemiology at the University of Texas Health Science Center at Houston.

CDC’s Uyeki said he was most concerned about H5N1 during the earlier clusters. That type of person-to-person spread doesn’t appear to be happening at this time, he said.

What happened on the mink farm?

Recent concern among public health experts has been fueled in part by evidence of infection in a variety of mammals. The growing list includes foxes, raccoons, skunks, bears and even marine mammals like seals and porpoises. Officials in Peru said three sea lions found dead in November tested positive for it, and the recent deaths of hundreds of others could be due to bird flu.

Then, last month, a European medical journal reported an October outbreak of bird flu at a mink farm in Spain of nearly 52,000 animals, where the disease spread like wildfire.

The mink have been fed poultry and wild birds in the area have been found to have bird flu. But the researchers said that however it started, they believe the virus then spread from mink to mink — a worrying scenario. No workers were infected despite wearing masks as part of COVID-19 precautions.

Jennifer Nuzzo, director of the Pandemic Center at Brown University School of Public Health, said the outbreak virus is being monitored for mutations that could make it more easily transmitted to humans and possibly between humans.

“That’s the real concern,” Nuzzo said.

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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Educational Media Group. The AP is solely responsible for all content.

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