This article originally appeared on KFF Health News.
Bird flu cases have more than doubled in the country within a few weeks, but researchers can’t determine why the spike is happening because surveillance for human infections has been patchy for seven months.
Just this week, California reported its 15th infection in dairy workers and Washington state reported seven probable cases in poultry workers.
Hundreds of emails from state and local health departments, obtained in records requests from KFF Health News, help reveal why. Despite health officials’ arduous efforts to track human infections, surveillance is marred by delays, inconsistencies, and blind spots.
Several documents reflect a breakdown in communication with a subset of farm owners who don’t want themselves or their employees monitored for signs of bird flu.
For instance, a terse July 29 email from the Weld County Department of Public Health and Environment in Colorado said, “Currently attempting to monitor 26 dairies. 9 have refused.”