Gov. Gavin Newsom declared a state of emergency Wednesday as the H5N1 bird flu virus spread from the Central Valley to dairy herds in Southern California, while federal officials confirmed the first case of serious illness in the U.S. in a hospitalized patient from Louisiana – a worrisome trend in the virus continues to spread about migratory birds across the country.
Newsom's declaration will enable a more efficient approach by state and local authorities to combat the virus and, according to a statement, “provide flexibility in staffing, contracting and other rules to support California's evolving response.”
“Building on California’s testing and surveillance system – the largest in the country – we are committed to continuing to protect public health, supporting our agricultural industry and ensuring Californians have access to accurate, timely information,” Newsom said in the press release statement. “Although the risk to the public remains low, we will continue to take all necessary measures to prevent the spread of this virus.”
According to the U.S. Department of Agriculture, 645 dairy herds in California have reportedly been infected with the H5N1 virus since August. Statewide, the number is 865, dating back to March, when the virus was first detected in herds in Texas.
A number of infections in domestic cats have also been detected in California, including three announced Wednesday.
According to the CDC, 61 people have been infected with the virus since March – the vast majority at dairies or commercial poultry plants. Most suffered from mild illnesses, including conjunctivitis, or pink eye, and upper respiratory tract irritation.
In California, 34 people have been infected with H5N1, with all but one contracting the virus through infected dairy products. The runaway was a child in Alameda County; The source of this infection has not been identified. There was also a suspected case of a Marin County child who drank raw milk known to be infected with the virus. The CDC was unable to confirm this child's illness.
The Louisiana case is causing concern among health officials because of its severity. Federal officials did not provide details about the patient's symptoms and referred all inquiries to the Louisiana Department of Health.
Emails and calls to that agency went unanswered.
According to CDC officials, the patient was reportedly in close contact with sick and dead birds from a backyard flock on the patient's property. The virus was a version of the H5N1 bird flu, which researchers have dubbed D1.1, circulating in wild birds.
The strain circulating in dairy cows is known as B3.13.
It was the D1.1 version that was discovered in November in a Canadian teenager who was hospitalized seriously ill. The cause of this patient's infection remains unknown.
According to Demetre Daskalakis, director of the CDC's National Center for Immunization and Respiratory Diseases, Louisiana health officials and the CDC are investigating the patient's contacts and conducting further genetic analysis of the patient's virus to determine what changes, if any, have occurred.
“These additional laboratory tests help us identify changes in the virus that are of concern, including changes that would indicate an increased ability to infect people or an increased ability to transmit from person to person, or changes that would indicate that currently available Diagnoses, antiviral treatments or… “Vaccine virus candidates may be less effective,” Daskalakis said in a press conference Wednesday morning.
He said analyzes so far had not revealed any changes in the virus that would make it “better suited to infection or spread among people.”
Analysis of the Canadian teenager's virus showed mutational changes that would make it easier for this version of H5N1 to infect people. However, it is unclear whether these changes occurred before infection – in the wild – or during the course of the child's infection.
None of the child's family members or contacts were infected, suggesting that the changes in the teenager occurred during infection and therefore the virus reached a dead end when it was unable to spread beyond the child.
These cases are similar to those recorded in the past in Asia and the Middle East, where the H5N1 virus resulted in a mortality rate of about 50%. Since the virus was first identified in 1997, 948 cases have been reported worldwide, resulting in 464 deaths.
The cases linked to the B3.13 strain circulating in the country's dairy herds have so far resulted in only mild symptoms.
Still, research suggests that changes in at least one virus isolate taken from a dairy worker in Texas gave rise to mutational changes that allowed airborne transmission between mammals and were 100% lethal in laboratory ferrets.
However, as in the case of the Canadian teenager, it is believed that the version only existed among the dairy worker and did not spread beyond that.
Other research shows that only one mutational change is needed for the B3.13 version to be transmitted efficiently between people.
The D1.1 version of the virus “worries me a little bit,” said Richard Webby, director of the World Health Organization's Collaborating Center for Studies on the Ecology of Influenza in Animals and Birds. “Not necessarily because I know it will evolve differently, but it has a different combination of H5 and N1 that could theoretically help support a different set of mutations” than the researchers in experiments with the B3. 13 version seen.
Daskalakis said the CDC still considers the risk to the general population to be low and that the agency is working to accelerate testing for influenza and avian influenza in clinical and public health laboratories “to expedite the identification of such cases through its routine influenza surveillance.” .
According to Newsom's office, “California has already established the largest testing and surveillance system in the country to respond to the outbreak.”