• An avian flu outbreak has struck birds worldwide since 2020 and infected cattle earlier this year.
• California Governor Gavin Newsom declared a state of emergency this week because of the virus.
• Health officials also confirmed the first “severe” case and hospitalization due to the H5N1 virus.

The burgeoning global outbreak of bird flu continued to spread across the country this week, with two key developments suggesting the virus is spreading at an increasingly worrying rate.

California Gov. Gavin Newsom declared a state of emergency over the virus on Wednesday, citing the troubling number of infected herds across the state in recent months and the need for more resources.

Since the state first identified the H5N1 avian influenza virus in cattle in late August, the California Department of Agriculture has confirmed 645 infected dairy herds.

Newsom’s announcement, meanwhile, came just hours after health officials confirmed the first serious case of bird flu in Louisiana, saying a person was hospitalized with an infection after being exposed to sick birds in their backyard.

In recent months, infectious disease experts have become increasingly nervous about the possibility of a human pandemic related to the virus, even though the Centers for Disease Control and Prevention has maintained that the public health risk to humans is low.

Here is the state of affairs.

Bird flu outbreak

The H5N1 virus first reemerged in Europe in 2020 and has since spread in birds around the world. The eruption has killed tens of millions of birds and tens of thousands of sea lions and seals in recent years.

According to the CDC, birds transmit the disease while migrating and can expose domestic poultry to the virus without showing any signs of it themselves.

At the beginning of the year, the virus spread to cattle herds for the first time in a major escalation. Then, in October, a pig in Oregon tested positive for the virus, a particularly concerning case because pigs can harbor both bird and human flu viruses.

To date, no human-to-human transmission is known. Still, infectious disease experts are wary of the possibility that H5N1 could ultimately become a human pandemic because of the increasing pattern of mammal-to-mammal transmission.

“If it continues to spread in animals, it will eventually cause problems for humans, either because we don’t have food, because they have to start wiping out herds, or because it skyrockets in humans,” says Dr. Jerome Adams, a former surgeon general and director of health equity at Purdue University, told Business Insider in April.

“The more it replicates, the greater the chance it has of mutating,” he added.

The ongoing multistate dairy outbreak, which is believed to have started in Texas, has infected 865 herds in 16 states and led to a growing number of human cases among dairy and poultry workers across the U.S., according to the CDC.

The CDC has so far confirmed 61 reported human cases and seven probable cases across the U.S., although some scientists estimate the actual number of infections is higher.

More than half of human cases are related to interaction with diseased cattle. The remaining infections resulted from contact with diseased poultry or had an unknown origin, the CDC said.

emergency

California’s announcement Wednesday will provide state and local authorities with more resources to investigate and contain the outbreak, Newsom said.

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“This proclamation is a targeted measure to ensure government agencies have the resources and flexibility they need to respond quickly to this outbreak,” the governor said in a statement.

Earlier this month, the Agriculture Ministry announced it would begin testing the country’s milk supply for traces of the virus and required dairy farmers to provide raw milk samples upon request. Until then, testing cattle for possible infections was almost entirely voluntary.

Dr. Monica Gandhi, a professor of medicine and deputy chief of the Division of HIV, Infectious Diseases and Global Medicine at the University of California, San Francisco, said the declaration will likely give California a greater ability to monitor dairy farms for signs of the virus.

But declaring a state of emergency could be a double-edged sword.

Phrases “like ‘state of emergency’ can cause panic given the fact that we have just gone through a pandemic,” Gandhi said.

And it’s not time to panic yet, she said.

Gandhi praised the CDC’s “very measured” message on the virus so far and said health authorities are closely monitoring the spread.