Deadly avian flu reaches California

Wave of virus has led to depopulation or euthanasia of more than 47 million birds

A caregiver holds a chicken at Farm Sanctuary in Acton, California, on Wednesday. Farm Sanctuary is home to rescued chickens, turkeys, cows, pigs and other farm animals. (MARIO TAMA / AFP)

An "unprecedented" wave of avian flu has hit Southern California, wiping out entire farms of domestic species and endangering wildlife. It also has the potential to further disrupt an already stressed supply chain, experts said.

The virus has been detected in 41 of 50 states in the United States. It has led to the depopulation or euthanasia of more than 47 million birds, said Maurice Pitesky, an associate professor in the poultry health and food safety epidemiology department at the University of California, Davis School of Veterinary Medicine.

"The current outbreak is about seven times the size geographically of that previous outbreak, and we're just about to enter fall migration when literally millions of birds will start moving into North America, into the United States, and a lot of them are likely to be carriers of that virus," he told China Daily.

The highly pathogenic H5N1 strain emerged among domestic waterfowl in Asia in 1996. By 2005, wild birds have brought the disease to poultry in Africa, the Middle East and Europe through migration.

The last major outbreak of bird flu in North America occurred in 2014 and 2015. It led to the deaths of more than 50 million birds in the US and resulted in an estimated $3 billion in damages.

But this avian flu epidemic will exceed all previous outbreaks, said experts, who described the surge as "unprecedented" in scope, breadth and lethality.

"We are in the midst of a completely unprecedented wildlife disease outbreak in North America," Rebecca Poulson, a University of Georgia research scientist who has been studying bird flu for 15 years, told The Atlantic. "We've never seen anything like this."

Low human risk

The highly pathogenic avian influenza, or HPAI, is highly contagious and often fatal in birds. The risk of humans contracting the disease is pretty low. However, experts urge people to be cautious when they interact with birds.

Pitesky said they do not believe the virus is highly transmissible to humans "at this point", but he added "it is biologically plausible as the virus mutates that it can mutate in such a way that it becomes infectious to humans".

On April 28, the Centers for Disease Control and Prevention confirmed that one person in Colorado has tested positive for the avian influenza. The patient was involved in the culling of poultry with presumptive bird flu virus. The patient experienced fatigue, but has since recovered.

"This is the second human case associated with this specific group of H5 viruses that are currently predominant, and the first case in the United States," the CDC said.

The virus hit Europe early last year. Nearly 50 million birds have been culled this season across 37 European countries, the European Union's Food Safety Authority said. Last fall, the virus reached North America and the US' East Coast, where it has been detected in wild birds, backyard flocks, commercial poultry facilities and wild mammals.

After landing in California this summer, HPAI has exploded across the state, killing many domestic and wild birds. A poultry farm in Fresno County became the first facility in the state this year to be affected by avian influenza. Nearly 34,000 chickens were euthanized to prevent further spread of the disease, state officials said.

As of Tuesday, HPAI has been detected in domestic flocks in at least 10 California counties. It has been found among wild birds in 22 counties, the state's food and agriculture department reported.

The outbreak has the potential to further disrupt the food supply chain, which already faces hurdles stemming in part from high prices for corn and soybeans, which are often used as poultry feeds.

"I am concerned about the ability to provide eggs and poultry meat, turkey, chicken at a scalable level over the next six months to one year, without prices going up significantly, without high levels of impact on the poultry industry as far as their ability to grow and trade and transport poultry," Pitesky said.