Postal workers exposed to anthrax during a series of attacks in 2001 felt they were not helped by U.S. health officials and lost trust in them, according to a report published on Wednesday.

Researchers at the Rand Corporation and George Washington University said the handling of the attacks - which killed five people, including two postal workers, and sickened 22 - created a lack of trust that would be difficult to overcome.

“Public health officials and others should begin now to develop the kinds of relationships necessary to communicate with a range of diverse groups,” they wrote in their report, published in the American Journal of Public Health.

“These relationships need to be nurtured and will take time to mature to a level of reliability that can be called on in times of crisis.”

Police still do not know who mailed anthrax-laced letters to a Florida newspaper, U.S. Senate offices and television networks in New York in September 2001. Spores from the letters leaked into the postal system, contaminating other mail.

Eight postal workers were infected by contaminated mail and two at Brentwood mail facility in Washington, D.C. died.

Dr. Janice Blanchard and colleagues at Rand and GWU interviewed the Senate and Brentwood workers who complained about a lack of information.

Although Centers for Disease Control and Prevention workers were assigned to both places, neither group of employees felt the CDC or the U.S. Postal Service were helpful, Blanchard found.

“I thought the CDC was something regarding the concern for public health,” the report quoted one Brentwood worker as saying. “I had a most high respect, but right now they’re just a part of the government to deceive.”

The postal workers, who were mostly black, were also acutely aware that mostly white Capitol Hill workers were given antibiotics right away to prevent anthrax infection.

“They’re special. They work for the Senate, they work for the government. We’re just poor, stupid people that don’t get anything,” the report quoted one as saying.