Clinton, who has said she plans to step down shortly, fainted after she became dehydrated due to the virus, the department said in a statement. She is recovering at home and being monitored by doctors.
“She will continue to work from home next week, staying in regular contact with department and other officials. She is looking forward to being back in the office soon,” the statement said.
No other information was provided and a spokesman for the department declined to comment.
Clinton was due to testify in congressional hearings Thursday on the Sept. 11, 2012, attack against a U.S. diplomatic post in Benghazi, Libya, which killed four Americans, including the U.S. ambassador. Her condition may cause the hearing to be postponed.
Clinton was scheduled to go to North Africa and the Persian Gulf region on Monday before she became ill. She apparently caught the virus during a recent visit to Europe.
Clinton has said she does not intend to serve in President Obama’s second term. The White House is expected to nominate her replacement and a new Defense secretary later this month. Defense Secretary Leon E. Panetta is also planning to step down.
[UPDATE, 1:40 p.m. Dec. 15: Clinton will not testify Thursday at the Senate Foreign Relations Committee hearing on Benghazi, a committee spokesperson said. Instead Deputy Secretary of State William Burns and Thomas Nides, the deputy secretary of State for management and resources, are expected to testify before the Senate committee as well as the House Foreign Affairs Committee.
"Secretary Clinton’s team contacted Sen. Kerry this morning to inform them of the secretary’s concussion," said Jodi Seth, a spokesperson for the Senate committee’s chairman, Sen. John F. Kerry (D-Mass.). "Sen. Kerry was relieved to hear that the secretary is on the mend, but he insisted that given her condition, she could not and should not appear on Thursday as previously planned."
Clinton was also set to appear the same day before the House Foreign Affairs Committee. Rep. Ileana Ros-Lehtinen (R-Fla.), that panel's chairwoman, said in a statement that it was “unfortunate” that Clinton would miss the hearing, and she wished Clinton “a quick and full recovery.”
Ros-Lehtinen said, however, that the committee had “tough questions about State Department threat assessments and decision-making on Benghazi,” and added, “This requires a public appearance by the secretary of State herself. Other Cabinet secretaries involved should also be held publicly accountable.”
President Obama called Clinton and wished her well, said Tommy Vietor, spokesman for the National Security Council.]
Kathleen Hennessey in the Washington bureau contributed to this report.