Nearly half of an elite U.S. epidemiology program known as the "disease detectives" were dismissed by the Trump administration Friday, according to sources familiar with the matter, dealing a blow to public health efforts as fears rise over bird flu.

The firings come as Elon Musk's Department of Government Efficiency pushes to downsize the federal government and as newly-confirmed Health Secretary Robert F. Kennedy Jr. vows to overhaul the nation's health agencies.

"I'm so angry," said a senior epidemiologist in the Centers for Disease Control and Prevention who supervised some of those affected by the cuts.