In other H5N1 developments, the WHO releases surveillance guidance for human cases, and the USDA announces new funding to mitigate livestock diseases.
A 3-year-old girl from Mexico recently hospitalized with H5N1 avian flu has died from her infection.
Newly affected herds are from Nevada and California.
Though no recent poultry outbreaks were reported in that part of Mexico, there were some detections in wild birds.
The latest H5N1 confirmations in pet cats come from Kansas, Pennsylvania, Iowa, and Illinois.
The source of the girl's virus might have been raw poultry, according to media reports.
Cats in multiple states got sick after eating the food, which was undergoing testing in the wake of a recall.
None of the samples were positive for H5N1 antibodies, but some showed earlier infection from human seasonal flu strains and swine flu strains.
The detection came less than a month after the state began its bulk milk sampling program.
The ratings aren't intended as a detailed threat assessment and don't indicate which pathogen is most likely to trigger the next pandemic, but instead are a guide for research investment.
