Deadly bird flu detected on farms in US

Deadly bird flu has been detected on poultry farms in South Dakota and Utah this month, prompting concern that there could soon be more outbreaks nationwide.

The highly pathogenic virus, officially called avian influenza and deadly to commercial poultry, was confirmed by the US Department of Agriculture (USDA) in a flock of 47,300 turkeys in Jerauld County, South Dakota, on Oct 4 and at a farm with 141,800 birds in Utah's Sanpete County on Oct 6.

South Dakota State veterinarian Beth Thompson told The Associated Press: "I don't doubt that we will have more cases. I would be very pleasantly surprised if we're done because migration [of wild birds] is just starting."

While the flu is highly transmissible among poultry, it is less commonly passed from animal to human and isn't considered a food-safety risk, according to the Centers for Disease Control and Prevention (CDC).

But as it hits other species, including some mammals, scientists fear the virus could evolve to spread more easily among people. Last week, Cambodia reported its third human death from bird flu this year.

The virus can be spread by droppings of wild birds, including geese, eagles and ducks, into poultry barns, on workers' footwear, clothing and farm equipment or by small birds, mice or dust particles.

The South Dakota and Utah cases were the first ones in commercial flocks since April, when the disease struck two turkey farms in the Dakotas. Before that, the virus had been found only sporadically in backyard flocks.

Last year, Utah's agriculture department said there were infections on 16 turkey farms, one egg farm and many backyard flocks. South Dakota farmers lost 3.96 million birds. Iowa lost 16 million birds.

Infections in any flock are monitored closely because they can spread to commercial poultry. Any commercial flock that becomes infected is destroyed. Nearby farms are also monitored for traces of the virus. Infected poultry aren't allowed into the country's food supply.

Between 2022 and the spring of 2023, US poultry producers have culled 59 million birds in 47 states — including turkeys and egg-laying chickens that were raised to be eaten by consumers.

This year's outbreak has cost poultry farmers an estimated $3 billion, according to USA Today. Last year, the country's most deadly outbreak ever cost $660 million, according to the USDA. It also caused a huge shortage of eggs and a spike in the price at supermarkets.

The toll from a 2015 outbreak, called the most expensive animal health disaster in US history with more than $1 billion in costs to the government, caused 51 million birds in 15 states to be killed to stop the spread of the virus.

Infections began in Europe but quickly spread to the US by February 2022. There are now strict restrictions in place on poultry imports from Europe.

Meanwhile, a study suggests that chickens genetically modified to be impervious to bird flu may one day prevent the spread of the disease on poultry farms.

Scientists from the University of Edinburgh, Imperial College London and the Pirbright Institute (an animal disease research center), said in the journal Nature Communications last week that they bred chickens with gene editing techniques.

The gene-edited chickens had a small section of their DNA altered to restrict the virus. When they were exposed to a normal dose of avian influenza virus, nine of 10 were unaffected, according to the researchers. But when exposed to an artificially high dose of avian influenza, five of the 10 birds became infected.

The gene-edited chickens appeared to not spread the virus further as they infected only one of four normal birds in the same incubator. There was no further spread to other gene-edited birds.

Only four human infections with low avian virus resulting in mild to moderate illness have ever been identified in the United States.

But in Cambodia this year. of the three human deaths attributed to bird flu, two of them were last week — a 2-year-old girl and a 50-year-old man who lived in a neighboring province, both of whom had exposure to poultry prior to their illness, according to the country's health ministry, the AP reported.

In February, an 11-year-old girl became the country's first bird flu fatality since 2014. Her father was also found to be infected but survived.

According to a global tally by the United Nation's World Health Organization, from January 2003 to July 2023, there have been 878 cases of human infection with avian influenza reported from 23 countries, 458 of them fatal. Cambodia had recorded 58 cases since 2003 of humans infected with bird flu.

Agencies contributed to this story.