New CDC research suggests that a small but significant percentage of dairy farmers working near infected cows have recently contracted H5N1, often without knowing.

A teenager in British Columbia, Canada has been hospitalized with a presumed case of H5N1 bird flu, the first detected human case in the country in the current outbreak.

The presentation, so brief as to be little more than a public service announcement, signals an abandonment of efforts to prevent the emergence of a wider avian flu pandemic.

Rising H5N1 bird flu cases in the U.S. prompted the CDC to study the virus in ferrets, revealing it may have the potential to spread and cause severe symptoms in other mammals.

Following a CDC study showing bird flu exposure among dairy workers, health officials recommend increased testing and preventative measures for farmworkers, even if they show no symptoms, to prevent virus spread and mutation.

A new study found some dairy workers showed signs of infection, even when they didn’t report feeling sick. Blood tests from 115 farmworkers in Colorado and Michigan found eight had antibodies that indicated previous infection with the virus.