The first person in the US to develop severe illness from H5N1 bird flu has been hospitalized in Louisiana, officials at the US Centers for Disease Control and Prevention (CDC) confirmed on Wednesday.
Officials believe the person had contact with sick and dead birds in a backyard flock, which would be the first time a person has contracted avian influenza from a backyard flock in the US – which the CDC’s Demetre Daskalakis called “notable”.
The news comes as the US continues to expand its efforts to track bird flu infections amid a growing outbreak. There have been 61 confirmed and seven probable cases of H5N1 in people in the US.
States will now be required to test bulk milk in order to understand the extent of the spread among dairy cows and identify new outbreaks, the US Department of Agriculture’s (USDA) announced earlier this month.
On Wednesday, California declared an emergency, seeking to streamline its response.
In California, the top milk-producing state, 649 herds – roughly 60% – have tested positive since late August, according to US data. Four southern California dairies tested positive on 12 December, “necessitating a shift from regional containment to statewide monitoring and response”, said the governor, Gavin Newsom. Earlier cases had been centered in the Central valley.
The declaration in the most populous state aims to allow more flexibility for staffing, contracting and other rules, Newsom said.
Labcorp also announced on Tuesday that the first commercial test for H5N1 was now available to the public with a physician’s order.
Another probable case of bird flu in a person in Delaware was identified in the first week of December through routine influenza surveillance, Tim Mastro, deputy director of communications for Delaware Health and Social Services, said in a statement.
This person did not have any known exposure to animals, Daskalakis said.
But “confirmatory testing at CDC was not able to confirm H5 infection”, Daskalakis said, so the probable case is not included in the tally of confirmed national cases.
H5N1 was detected at the only wastewater site that monitors H5N1 in Delaware during the week of 7 December, near Georgetown, Delaware, the center of the state’s poultry operations.
“There have been no detections in poultry or livestock in Delaware,” said Stacey Hofman, chief of community relations for the Delaware department of agriculture.
“We know that H5N1 is in the Atlantic flyway, and with a large number of migratory waterfowl in Delaware at this time, it is believed that is the cause of this detection” in wastewater, she said.
Among humans, the confirmed case in Louisiana and the probable case in Delaware “do not change CDC’s current risk assessment for the general population, which remains low”, Daskalakis, director of the National Center for Immunization and Respiratory Diseases, told reporters on Wednesday.
“[But] people who work with or have recreational exposure to infected animals are at higher risk of infection,” he said.
Anyone who comes into contact with animals should take precautions, he said, including wearing a respirator and getting tested if symptoms develop.
The person in Louisiana was sickened by the same variant as the teen in British Columbia, who remains in critical condition after six weeks of illness.
This variant, found in wild and domesticated birds, is different from the one circulating in dairy cows, officials said. Additional genomic sequencing of the virus is still under way at the CDC.
The person in Louisiana first tested positive for flu A, and the sample was discovered to be bird flu upon examination by the state lab as part of regular monitoring of positive flu tests.
The CDC would not say what symptoms the patient experienced or what kind of support they have needed during their hospitalization, citing patient privacy concerns. But Daskalakis said: “The patient was, in fact, hospitalized, [and] was severely ill related to their influenza infection.”
Louisiana public health officials are conducting a case investigation, monitoring contacts who may have been exposed, and offering testing and antivirals as needed, he said.
Previously, a patient in Missouri with underlying conditions tested positive for bird flu after no known exposure and spent three days in the hospital.
There has been no known human-to-human transmission of bird flu in the US during this outbreak, Daskalakis said.
While the US has stockpiled millions of H5N1 shots, those vaccines have not yet been authorized by the US Food and Drug Administration. Officials on Wednesday did not announce any changes in the US vaccination strategy.
Reuters contributed reporting
