Only doctor in Senate: 'Things under control'

WASHINGTON (CNN) -- As health investigators spent Thursday combing Capitol Hill offices for traces of anthrax, the only physician in the Senate sought to reassure the Washington community and the country that "things are under control," despite positive tests for anthrax exposure in 31 people there.

"The system is working. People are working together in a harmonious, almost symphonic way," Sen. Bill Frist, R-Tennessee, told a news conference.

VIDEO Anthrax threat shut down the U.S. House of Representative, but the U.S. Senate stayed open for business. CNN's Jonathan Karl reports (October 18) Play video (QuickTime, Real or Windows Media)

"The anxiety continues to bubble up from individuals, and everybody is doing their best with appropriate counseling as we go through," said Frist, who is a surgeon.

Nasal swabs were taken from more than 1,600 people who were in the Hart Senate Office Building Monday when a letter containing anthrax was opened in the offices of Senate Majority Leader Tom Daschle, D-South Dakota.

Frist said results from about 870 of the tests were back and 31 people were found to have been exposed -- 23 in Daschle's office, three in the adjacent office of Sen. Russell Feingold, D-Wisconsin, and five Capitol police officers.

So far, anthrax has been found in two sites on Capitol Hill -- Daschle's office in the Hart building and a Senate mailroom in the Dirksen Senate Office Building.

The Centers for Disease Control and Prevention advised that anyone who was on the fifth or sixth floors of the Hart building Monday to complete a full 60-day course of antibiotics, regardless of the results of their nasal swab.

"We err on the side of over treating than under treating," said Rima Khabbaz of the CDC, noting that one of the people who tested positive had been outside Daschle's office in a hallway. "That's why the decision to go broadly and treat everyone on those floors."

Health investigators planned to continue their sweep of the Capitol complex Friday and through the weekend. They were wiping down surfaces, vacuuming areas and even testing the air for any trace of anthrax, said Roger Gibbs of the Department of Defense.

The Senate was in session Thursday but the House stood empty. House leaders decided Wednesday to recess until Tuesday.

House Minority Leader Richard Gephardt, D-Missouri, defended the decision, which was criticized by some senators.

"We've got a responsibility to the young people that are here to make sure people aren't in harm's way, and we have a responsibility to make sure that these terrorists don't succeed, so it was the right thing to do," Gephardt said.