U.S. Army veteran Matt Schermerhorn couldn’t give blood for years because he was stationed in Europe during a deadly mad cow disease scare there. Now, he’s proud to be back in the donor’s chair.

Schermerhorn, 58, is among thousands of people, including current and former military members, who have returned to blood donation centers across the country after federal health officials lifted a ban that stood for more than two decades.

“It’s a responsibility. It’s a civic duty,” said Schermerhorn, who donated on Veterans Day at the ImpactLife center in Davenport, Iowa. “You really don’t have to go out of your way too much to help your fellow man.”

Blood collectors nationwide are tracking down people like Schermerhorn, U.S. citizens who lived, worked or vacationed in the United Kingdom, France, Ireland or served at military bases in Europe during various periods between 1980 and 2001, as well as anyone who received blood transfusions in those three countries anytime since 1980.

Since 1999, those people have been banned from giving blood in the U.S. for fear that they’d been exposed to mad cow disease. Outbreaks of the cattle-borne infection swept through Europe, eventually killing at least 232 people, mostly in the U.K. Four cases have been reported in the U.S., all in people who likely acquired the infections abroad, health officials said.