California officials said the decision to declare the emergency was made after H5N1 was detected in cattle in the south of the state.
Newsom said on Thursday: “This proclamation is a targeted action to ensure government agencies have the resources and flexibility they need to respond quickly to this outbreak.
“While the risk to the public remains low, we will continue to take all necessary steps to prevent the spread of this virus.”
California ended its Covid state of emergency in February 2023, having issued it in March 2020.
Earlier on Thursday, Louisiana said an individual had suffered the US’ first severe reaction to the H5N1 virus after being exposed to “sick or dead birds” on their property.
“The patient is experiencing severe respiratory illness related to H5N1 infection and is currently hospitalised in critical condition,” said Emma Herrock, a spokesman for the state health department.
California’s first bird flu case was detected in dairy cows in the state on August 30, and the first case in a human on October 3 in a dairy farm worker.
In late November, a child was confirmed to have been infected with bird flu, marking California’s first infection that was not linked to exposure to dairy cattle or poultry.
Officials revealed last week that they were investigating whether the child had become infected after drinking raw milk.
Last month, a teenager was sent to hospital after contracting bird flu in Canada, suffering severe lung damage and undergoing what was described as a “rapid” deterioration.
The teenager had not come into contact with infected cattle or birds, although they had been exposed to dogs, cats and reptiles.
