After a month with no H5N1 avian flu detections in dairy cattle, the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) today reported a positive test involving a herd from Texas, raising the nation’s total since early 2024 to 1,079 infected herds in 17 states.
The detection is Texas’s first since May.
Also, APHIS reported another H5N1 outbreak at a commercial turkey farm, the second recent detection in South Dakota. The new report involves a facility in Beadle County that houses 52,600 birds. Other outbreaks in turkeys over the past week occurred in flocks in Faulk County, South Dakota, and in Dickey County, North Dakota.
Source of California child’s H5N1 infection still a mystery
In related news, investigators from California and their partners at the Centers for Disease Control and Prevention (CDC) yesterday published their investigation findings into one of two unexplained H5N1 infections in California children. They published the details in Morbidity and Mortality Weekly Report.
The school-age child’s symptoms included fever, muscle pain, abdominal pain, and conjunctivitis (“pink eye”). They began on December 13, 2024, lasting 1 week and involving two healthcare visits.Â
The first visit was at a local emergency department, where staff collected a nasopharyngeal sample that tested positive for influenza A and was sent to the San Francisco Department of Public Health’s lab as part of enhanced surveillance. Further subtyping identified H5N1 on January 9, and follow-up sequencing revealed that the virus belonged to the B3.13 genotype that had been circulating in dairy cattle, other mammals, poultry, and wild birds.
No other family members had been sick, and polymerase chain reaction and serology testing of some of the child’s close contacts revealed no evidence of human-to-human spread. A sample collected from the child on January 10 was still positive, but specimens collected 4 days after that were negative.
Poultry not likely the cause
The family lived in an urban environment and had a pet dog. A family member had bought raw poultry at a live-bird market more than 2 weeks before the child’s symptoms began. It was cooked and eaten the same day. Investigators wrote that poultry wasn’t the likely source, given that poultry-market testing was negative, the child wasn’t exposed to raw poultry, and the parents weren’t sick. The investigators said the child spent time outdoors at school and may have had environmental exposure to the virus.
The researchers said continued surveillance and real-time subtyping at public health labs is a key part of novel flu surveillance and that detection of B3.13 serves as a reminder that the virus continues to transmit across susceptible species, requiring a strong One Health approach.
