Officials at the Bethesda Naval Hospital are checking the facility's water supply for the bacteria that causes Legionnaires' disease following the recent deaths of two elderly cancer patients from the rare malady.

Lt. Cmdr. Claude Shehane, a hospital spokesman, said tests have shown "no evidence that we have a problem." He said that after the death of the second patient last month, colonies of the bacterium legionella were found on shower heads and faucets in 17 of more than 91 spots checked in the hospital and surrounding buildings.

But Shehane said that number is not considered a high concentration and no bacteria have shown up in the hospital's water tanks or water lines. "We have found no particular relationship to indicate a common source" of infection, he said.

No other patients in the hospital, he said, have been stricken with the disease, which experts estimate strikes 25,000 people a year. "This is not a panic situation," he said.

Experts say Legionnaires disease no longer inspires the terror it did when it was discovered eight years ago with the deaths of 29 people at an American Legion convention in Philadelphia.

Since then, antibiotic treatment has reduced the death rate greatly.

Dr. Steve Cochi, an expert on the disease at the federal Centers for Disease Control in Atlanta, has said the disease "is not a deadly killer any more than other forms of bacterial pneumonia which are more common." However, it still kills about a fifth of its victims who are already sick or are undergoing treatment that weakens their immunity systems.

The naval hospital will never be able to tell whether the patients who died brought the bacteria in with them or became infected in the hospital, according to Shehane.

The patients, a man and a woman, died within three weeks of each other at the 500-bed hospital on Wisconsin Avenue, which is frequented by the government's highest ranking officials. Both began showing symptoms of pneumonia, of which Legionnaires' disease is a rare form, while undergoing treatment in the hospital for terminal cancer, Shehane said. An autopsy performed on the first patient, who died on Sept. 24, revealed Legionnaires as the cause of death, he said.

Shehane said hospital workers checked for legionella bacteria in the area in which that patient was treated. Asked if they discovered any of the bacteria, he said, "Not to my knowledge."

On Oct. 13, on another ward, the second patient died. Shehane said he believed that patient's doctors had diagnosed the disease and were treating it at the time.

At that point, according to Shehane, officials began sampling faucets and shower heads in the hospital and in other nearby buildings such as the barracks across the street. They also tested the medical center's water tanks and incoming lines.

The colonies of the cigar-shaped bacterium were found only in Building 10, which houses the inpatient wards. He said hospital workers replaced the contaminated showerheads and faucet parts and are taking more samples to see if the bacterium reappears, which would be an indication of contamination of the hospital's water supply itself. He said he did not know if any results from the new tests were in yet.

The disease is apparently contracted when the legionella, which live in water and are common in the environment, are blown into the air from cooling systems or faucets and are inhaled. Humans cannot transmit the disease to each other.