Farmworkers have been exposed to milk infected with the bird flu virus. But there has virtually been no testing on farms, and health officials know little about who may be infected.Even as it has become increasingly clear that the bird flu outbreak on the nation’s dairy farms began months earlier — and is probably much more widespread — than previously thought, federal authorities have emphasized that the virus poses little risk to humans.Yet there is a group of people who are at high risk for infection: the estimated 100,000 men and women who work on those farms. There has been no widespread testing to see how many may be infected. No one has been vaccinated against bird flu.That leaves the workers and their families vulnerable to a poorly tracked pathogen. And it poses broader public health risks. If the virus were to find its way into the wider population, experts say, dairy workers would be a likely route.“We have no idea if this virus is going to evolve to become a pandemic strain, but we know today that farmworkers are being exposed, and we have good reasons to think that they are getting sick,” said Jennifer Nuzzo, director of the Pandemic Center at Brown University School of Public Health.A majority of dairy farmworkers are Spanish-speaking immigrants, often undocumented, who may not have paid sick leave or be protected by occupational safety laws. They may lack access to medical providers, and their employers can be intolerant of absences.“This sector of workers is not only at the very, very highest risk because they’re having that direct, intimate contact with discharge, raw milk, with infected animals, but they’re also at the very, very highest level of risk in terms of having no social safety net,” said Elizabeth Strater, an organizer with United Farm Workers.We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe.