The US Centers for Disease Control and Prevention (CDC) said today that its tests have confirmed H5N1 avian flu in California's recent suspected case, involving a child who had no known exposure to infected animals.
Also, California announced another confirmed H5 case in a dairy farm worker. The new developments lift the state's total to 29 human cases of H5 avian flu and the national total since the first of the year to 55.
California confirmation marks first infection in US child
The CDC statement noted that the confirmation marks the nation's first H5 infection in a child, and it reiterated much of what the California Department of Public Health (CDPH) said in its initial announcement of the case on November 19.
The child's infection was detected through California's flu surveillance system, and the level of viral material in the specimen was low. Follow-up tests several days later were negative for avian flu but were positive for other common respiratory viruses.
The child is recovering, and all family members tested negative for H5 avian influenza but positive for the same common respiratory virus as the child. Contact tracing continues, and there is no sign of human-to-human spread.
Investigation into the child's exposure to H5N1 is still under way, the CDC said.
Hawaii poultry virus is A3 genotype
In other H5N1 developments, the Hawaii State Department of Health yesterday said tests in people who had contact with an infected flocks are all negative, even in those who had high-risk exposure.
Of 54 people who had potential exposure, 34 were offered free testing due to unprotected exposure to the sick ducks and geese that were part of a backyard flock. Of those, 29 agreed to testing, including 13 who had at least one respiratory virus symptom. All of the people who had the highest risk—such as those who had prolonged contact with visibly sick birds—agreed to testing.
Two of the people who had symptoms were positive for common cold viruses.
Investigations are still under way in people who were exposed to birds from the flock at a pet fair. At least four have been tested, and all were negative.
Genetic sequencing from the virus from the sick birds found the A3 genotype, which was first identified in wild birds in Alaska in 2022. The genotype is different from the one infecting US dairy cattle and the one that infected a teen who is critically in British Columbia. "It is unknown whether genotype A3 is likely to infect humans or other mammals," officials said.
California dairy farm outbreaks top 400
On the animal health side, the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service confirmed four more outbreaks in dairy cattle, all from California. The latest confirmations push California’s total to 402 and the national total to 616 from 15 states.
The group reported no new confirmation in poultry flocks. California is grappling with several outbreaks on commercial poultry farms, as states in the West continue to report sporadic outbreaks. Also, a handful of Midwestern states have reported new outbreak activity this week.
