Without widespread testing, health officials have little sense of who is infected, when to treat patients and how to monitor their close contacts.
In that sense, the bird flu outbreak plaguing the nation’s dairy farms is spreading virtually unobserved.
But while officials have tested thousands of cows and are monitoring hundreds of farmworkers, only about 60 people have been tested for bird flu.
Officials do not have the authority to compel workers to get tested, and there is no way for workers to test themselves.
In the current outbreak, just four dairy workers and five poultry workers have tested positive for H5N1, the bird flu virus, but experts believe that many more have been infected.
Locations:
U.S