A recent bird flu outbreak at a mink farm has raised concerns about the virus spreading further to people.
Scientists have been monitoring 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 a poultry market.
When bird flu infects other and diverse animals, such as in mink farms, the fear is that the virus could develop and spread more easily among humans, and could lead to a pandemic.
Scientists say another bird flu was behind the 1918-1919 flu pandemic, and avian viruses played a role in other flu pandemics in 1957, 1968, and 2009.
However, the risk to the general public is now low, said Dr. Tim Uyeki from the US Centers for Disease Control and Prevention.
Take a look at the bird flu virus and why it’s a concern again:
What is bird flu?
Some flu viruses primarily affect humans, while others primarily occur in animals. For example, there is the flu that occurs in dogs, plus the swine flu virus – or pigs. And then there are avian viruses that spread naturally in wild aquatic birds like ducks and geese, then to chickens and other domestic fowl.
The bird flu virus that is attracting attention today – Type A H5N1 – was first identified in 1959, by investigators parts is has is for the future. Like other viruses, it has evolved over time, producing new versions of itself.
In 2007, the virus was found in more than 60 countries. In the US, it has recently been found in wild birds in every state, as well as in commercial poultry operations or backyard flocks in 47 states. Since the beginning of last year, tens of millions of chickens have died from the virus or died to prevent the outbreak from spreading, one reason said to be the rising price of eggs.
How often do people get bird flu?
The 1997 Hong Kong outbreak was the first time this bird flu was blamed for severe human illness. Of the 18 people infected, six died. To prevent the outbreak, the Hong Kong government closed the live poultry market, killed all the birds in the market, and stopped importing chickens from southern China. It worked, for a while.
The symptoms are similar to other flu, including cough, body aches and fever. Some people have no visible symptoms, but some have severe ones. life-threatening pneumonia.
Globally, nearly 870 human infections and 457 deaths have been reported to the World Health Organization in 20 countries. But the pace is slowing and there have been about 170 infections and 50 deaths in the past seven years. In most cases, infected people get it directly from infected birds.
The first and only US case occurred last April. A prison inmate in a work program took it upon himself to kill an infected bird at a poultry farm in Montrose County, Colorado, in the western part of the state. The only symptom was fatigue and he recovered.
Can it spread between people?
In some cases, investigators have concluded that the bird flu virus appears to be spreading from person to person. That happened in Thailand, Vietnam, Indonesia, China and Pakistan, most recently in 2007.
In each cluster, spread in the family of the sick person at home. Scientists don’t believe it can spread easily through casual contact, like seasonal flu. But viruses mutate and change. Scientists are concerned about the increasing number of opportunities for bird flu to mix with other flu viruses in infected people or animals and mutate, making it easier to spread to people.
It doesn’t take much for that to happen “and then we’re going to be in a very difficult situation,” said Dr. Luis Ostrosky, chief of infectious diseases and epidemiology at the University of Texas Health Science Center in Houston.
The CDC’s Uyeki said the biggest concern about H5N1 was during earlier clusters. Such human-to-human transmission is not seen today, he said.
What happened to the mink farm?
Recent concern among public health experts has been prompted, in part, by the detection of infections in various mammals. The extensive list includes foxes, raccoons, skunks, bears and even marine mammals like seals and dolphins. Officials in Peru say three sea lions found dead in November tested positive, and hundreds of other deaths may have been caused by bird flu.
Then last month, a European medical journal reported on an outbreak of bird flu in October at a mink farm in Spain with nearly 52,000 animals, where the disease spread like wildfire.
The mink was fed poultry, and wild birds in the area were found to be infected with bird flu. But researchers say that once it starts, they believe the virus can then spread from mink to mink – a worrying scenario. None of the workers were infected, although they wore masks as part of the COVID-19 precautions.
Jennifer Nuzzo, director of the Center for Pandemics at Brown University’s School of Public Health, said the outbreak virus is being monitored for mutations that could make it easier to transmit to people, and possibly among people.
“That’s really worrying,” Nuzzo said.
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The Department of Health and Science of the Associated Press receives support from the Howard Hughes Medical Institute’s Science and Education Media Group. AP is solely responsible for all content.
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