Dan Rather got the call at midnight Wednesday.

His assistant of five years, Claire Fletcher, told him she was the latest victim of anthrax.

The CBS anchor, understandably, is angry.

"But this is war, and in war, people do bestial, savage things," Rather said in an interview yesterday. "The law of the jungle is don't lose your temper."

Fletcher, 27, is recovering and has not missed a day of work. The bubbly, British-born Fletcher competes in triathlon events of running, swimming and biking, and despite the infection she joined a 13-mile Central Park run 12 days ago.

"She's been heroic," said Rather, who does not plan to be tested. "I'm aware there's some danger here but have it in perspective," he added.

CBS executives say they don't know if the spores came from a contaminated letter handled by Fletcher, who has the skin form of anthrax. "Police tell me they're working on the assumption that it came in the mail, but Claire does not remember anything suspicious," Rather said.

CBS News President Andrew Heyward offered a similar response at a Manhattan news conference. "We have no knowledge of any letter or any other suspicious material coming into the building," he said.

"Our biggest problem is not anthrax," Rather told reporters. "Our biggest problem is fear."

The atmosphere at CBS's West 57th Street headquarters is one of concern. Kim Akhtar, Rather's spokeswoman, who sits near Fletcher and also handles some of the anchor's mail, has not received the results of her nose swab test. "We're just trying to keep a level head because there's no sense in panicking," Akhtar said.

Yesterday's disclosure, coming after anthrax diagnoses of an assistant to NBC's Tom Brokaw and the baby of Carole Simpson's producer at ABC, means all three broadcast networks have been hit in New York.

Stephen Ostroff, epidemiology director for the federal Centers for Disease Control and Prevention in Atlanta, said that although further investigation of the three network cases is needed, "the pattern here appears to be virtually identical."

The diagnosis of Fletcher, who first showed symptoms early this month, was slow in coming because the NBC and ABC cases had not been made public. When Fletcher got a blemish on her cheek, "it looked like a bug bite or spider bite," Rather said. "Nobody was thinking about anthrax."

A nose swab came back negative and blood-test results were still pending when the NBC case became public last Friday. Fletcher decided to get a biopsy, which detected the presence of anthrax.

ABC News President David Westin told his staff that results for 59 of 74 environmental samples from the network's building have come in, all negative. About 175 ABC staffers are being tested each day in the company cafeteria.

On Wednesday, Rather was sympathizing with Brokaw's declaration that he was "very angry" over the attack on his assistant, Erin O'Connor. "I'm doing the very best I can not to let my emotions show in my reporting," said Rather, who fought back tears during a recent David Letterman appearance.

Rather turned yesterday's news conference into a recitation of CBS's values.

He seemed determined in the interview to project a resolute image, saying that "our little band of brothers and sisters here in the office" would not succumb to what he called "psychological warfare."

"We're not going to flinch, we're not going to bend, we're not going to swerve," Rather said. "We pride ourselves on being a classy outfit, and class never runs scared."