A recent study led by the US Centers for Disease Control and Prevention (CDC) has revealed that 7% of workers on dairy farms with infected cows showed signs of past H5N1 bird flu infection, despite many of them not displaying symptoms.
The study’s findings suggest that infections among farm workers may be higher than previously recorded, as the official count only includes cases where active symptoms were reported and tested.
The study, a collaboration between the CDC and health departments in Colorado and Michigan, was published in the CDC’s Morbidity and Mortality Weekly Report. Following these findings, the CDC has updated its recommendations for dairy workers, expanding testing and treatment protocols to include those without symptoms if they have been exposed to infected animals. Previously, the CDC only advised testing and treatment for symptomatic workers.
The CDC is now urging that all workers on farms with known infections be tested and treated with the antiviral medication Tamiflu after potential exposure. High-risk exposures include incidents such as contact with raw cow’s milk or working closely with infected animals without adequate protective equipment. Dr. Nirav Shah, Principal Deputy Director of the CDC, explained that these recommendations aim to limit both individual health risks and the virus’s potential for mutation.
“This approach is designed to prevent the virus from spreading and evolving… By testing, treating, and isolating as many cases as possible, we limit its chances of becoming more dangerous,” Shah said.
The study involved blood testing 115 farm workers in Michigan and Colorado. Of the eight workers with antibodies, only half recalled experiencing mild symptoms, such as eye redness or fever. The study also highlighted a significant gap in awareness and protective measures: none of the workers wore recommended respiratory protection, and fewer than half used eye protection.
To address this, the CDC emphasized the need for increased education, especially for farmworkers with limited access to healthcare and protective equipment. All eight workers who tested positive spoke Spanish, underscoring the need for culturally accessible health guidance.
The CDC’s new guidelines mark a shift in its approach to addressing H5N1 exposure risks in agricultural settings. By expanding testing efforts and increasing preventive measures, the CDC aims to better protect workers and limit opportunities for viral spread. The agency reiterated that the current risk to the general public remains low, while emphasizing the importance of vigilant monitoring and testing among those directly exposed.
CNN, the Associated Press, and STAT contributed to this report.
