"Legionella is widespread in water systems," said Dr. Robert F. Breiman, one of the people who supervised the examination of Celebrity Cruises' ship Horizon for the Centers for Disease Control and Prevention. "If we cultured the cooling towers up there in New York City, we'd find Legionella in 50 percent. But the vast majority do not transmit disease. And we don't have the answer why, and right now cannot predict."
Dr. Breiman, who is the chief of the respiratory disease epidemiology section of the C.D.C. in Atlanta, said that for that reason, testing water samples from all cruise ships for Legionella would still not detect where Legionnaires' disease might originate.
Although the centers have not completed their comparison interviews of Horizon passengers, of the infected as well as the healthy, Dr. Breiman's associate, Dr. Martin F. Cetron, said that the sand used in the filters for the whirlpool tubs was "strongly implicated" as the source of transmission for the Legionella bacteria. Bromine and chlorine are used as bactericides to treat water in whirlpool tubs, and Dr. Breiman said there was no reason to consider this treatment inadequate. "But even the best bromination won't be effective in a situation where the bacteria hide in sediment," he said. Traces of Legionella bacteria were found in sediment in the sand filter.
No More Whirlpools
The centers have confirmed 11 cases of Legionnaires' disease among the passengers of the Horizon; 24 other cases are suspected. One passenger died in what was the first cruise ship outbreak of Legionnaires' disease known to the Government."Given that we've never seen anything like this before," Dr. Breiman said, "we're hoping it's just an anomaly."
When the Horizon went back to sea, the three whirlpools, all linked in one system, were shut down.
Al Wallack, a senior vice president of Celebrity Cruises, said that the filters had been removed and stored for any future study. Dr. Cetron said Celebrity had not been asked to shut the whirlpools permanently, but both the line and the Government want to keep them out of service until more is known about the problem.
As for requiring that all ships' water systems be flushed with a chlorine solution 25 times the usual strength, the method by which the Horizon was cleansed so it could re-enter service on July 31, Dr. Breiman said: "It's not easy to get rid of the bugs. You have to keep doing it over and over. It's very corrosive to plumbing, and you do not want to do it routinely."
The issue before his department, which is also being studied elsewhere, is to find "a better way to know when there's a problem," he said, to learn to predict when the all-too-common Legionella will be transmitted to humans and make them ill. Dr. Breiman said that his agency dealt with 5 to 10 outbreaks a year of Legionnaires' disease, although it's possible that smaller outbreaks are managed by local health departments. The most frequent source is a building's cooling tower, also known as an "evaporative condenser," but he said that considering his estimate that 50 percent of these might contain the bacteria, the rate of disease transmission was infinitesimal.
The annual total of cases of Legionnaires' disease in the United States is estimated at 25,000, some involving mild symptoms. The disease is treatable with antibiotics, but the fatality rate in an outbreak can be as high as 15 percent.
Legionella thrives in warm water, not above 125 degrees. Water at swimming pool temperature, 80 to 88 degrees, is too cool. Dr. Breiman said that most cruise ships store hot water for showers at 140 degrees, which kills the bacteria. Whirlpool or hot tub temperature, usually 98 to 103 degrees, "could not be better" for growth of the bacteria, he said. "It's a place where technology and disease trip over each other. The water is comfortable for you, it's comfortable for the bacteria." In addition, he said, the water contains enough organic material, particularly amoebas, for the bacteria to hide in.
It's in the Spray
Transmission is usually by inhalation, breathing an aerosol -- a suspension of particles in the air, Dr. Breiman said. This is one of the things people like about whirlpools -- the spray around the face.
James F. Ryan, marketing director of Perkin-Elmer in Norwalk, Conn., the company that makes the laboratory equipment used by the C.D.C. to identify the Horizon bacteria's DNA, said he had a sudden realization while on a recent trip to North Carolina. His sons turned on the whirlpool bath at the beach house they were staying in, and "it sprayed up like a soda can." Knowing what he knows, he remarked that whirlpools would probably be banned if so many people with bad backs didn't swear by them.
And it's not just those with bad backs: older people like whirlpools, too. And they are at higher risk for Legionnaires' disease, as are smokers and people with respiratory problems, immune-system deficiencies and bad hearts.
Dr. Cetron said that in the fall the C.D.C. will hold a conference of public health officials, Legionella experts and representatives from the spa and cruise industries to look at the problem. After that the centers will issue recommendations that will apply to resorts with whirlpools as well as to cruise ships. One issue to be discussed, Dr. Breiman said, is whether filters should be easily replaceable, which is not the case now. "Perhaps they should be designed as a removable unit, like an auto air filter," he said.
Should older people avoid whirlpool baths? "In regard to the Horizon, it is easy to say in retrospect," Dr. Breiman said. "But we still do not know enough to say that in general."
Legionnaires' disease was identified and named in 1976 when 221 people at an American Legion convention at the Bellevue-Stratford Hotel in Philadelphia fell ill with this particular pneumonia. Thirty-four died.
Making Pop Inspections
Even if the Horizon outbreak was an anomaly, the case will probably have an impact on the cruise sanitation program of the C.D.C. Its current inspection program has focused on storage and delivery of things people ingest -- water and food -- to prevent diarrhea, the most common scourge of cruising. If Legionella transmission becomes a problem again, the inspection program will end up being involved, Dr. Breiman said.
The Vessel Sanitation Program now involves two unannounced inspections a year for every ship that sails from United States ports regularly for more than six months a year. The vessels are charged per inspection on the basis of gross tonnage: $799 for small ships, $6,388 for the largest. A passing grade is 86, and the Government has the right to recommend that a cruise be canceled if conditions are hazardous, particularly if they involve the drinking water. A score of less than 86 does not mean cancellation. The summary report of July 15 showed that 6 of 79 ships scored lower than 86.
The Horizon's score for an inspection it underwent on Feb. 4 was 94. The chief of the sanitation program, Don W. Turner, said that Celebrity Cruises had had "a good track record" on inspections.
Mr. Turner and his three assistants, who are based in Miami, are commissioned sanitarians or civil engineers. In all, 127 cruise ships are listed on the July 15 report, some of which call in the United States only irregularly. To keep up with the numbers, the inspectors fly to New York, the West Coast, the Virgin Islands and Alaska so too much time doesn't pass between inspections.
The Checklist
They check 42 items under eight headings: water, food protection and source, personnel, equipment and its washing, solid and liquid waste disposal, toilet and handwashing facilities, pest-control and toxic substances, and miscellaneous. In Miami, Fort Lauderdale, Fla., New York and Los Angeles, inspections are carried out on turnarounds, which means they do not cover preparation of a full dining room meal because passengers are debarking and arriving. Full meal service can be reviewed midcruise when a ship is in port, in the Virgin Islands, for instance. When Mr. Turner is unable to observe the preparation of a full meal, he tries to schedule the next inspection to allow this.
The worst offenses cost five points: five points are deducted if the drinking water is not halogenated -- usually chlorinated -- to a level of two parts per million at the time of storage; five points if the equipment for monitoring halogenation is not in order; five points if food workers do not have clean hands, do not practice good hygiene or do not wear clean uniforms. A deficit of 15 points means a failing grade. When a ship fails, a reinspection is made in 30 to 60 days.
Even though all but two cruise ships that dock in American ports are registered in other countries, the Public Health Service, the agency that directs the C.D.C., has the authority to take steps to "prevent the introduction, transmission or spread" of a communicable disease from a foreign country to the United States. Mr. Turner said that until the recent incident involving the Horizon, no cruise ship had been prevented from sailing during his six years in the inspection program.
When Mr. Turner inspected the World Discoverer of Reederei of Bremen, Germany, marketed in North America by Clipper Adventure Cruises, while it was overnighting in Ketchikan, Alaska, on June 7, he gave it a score of 42.
He said he left notations on improvements he wanted made immediately, and when he came back the next day, they had been made and the ship sailed. On a reinspection on July 8, reported on July 15, the ship got an 88. Mr. Turner said it was rare for a vessel with owners "who understand our system and requirements" to fail two inspections in a row, though understanding the rules has been a problem with some vessels from Ukraine.
In a case like the Horizon's, in which a state health department reports an outbreak, inspectors go to the ship immediately, along with epidemiologists from the C.D.C. in Atlanta. Blood and stool samples are taken from both the ill and the healthy. Dr. Breiman said he considered the whirlpool tubs to be suspect when he first saw them, but dozens of possibilities had to be tested. "While I was in New York for this I visited my aunt and saw a giant cooling tower on an adjoining building," he said. "It was throwing off an aerosol: it would be a perfect suspect."
Two Public Reports
The sanitation program issues two types of public reports, which are available together on request. The most recent scores for all ships visiting the United States, along with the date of inspection, appear on the Summary of Sanitation Inspections, a single card known as the "green sheet." Travel agents can be expected to have copies.
A prospective passenger may also request the results of the latest inspection of a vessel. A document of several pages, it itemizes the score, gives the inspectors' descriptions and a response by the cruise line concerning what it did to correct any problems. When the Maasdam got only an 81 in April, the line reported disciplinary action taken against the chef involved in the problems as well as replacement of equipment and procedure changes. On May 9, the ship passed with a 96.
Requests for a copy of the summary green sheet or the inspection report of a vessel should be addressed to: Chief, Vessel Sanitation Program, 1015 North American Way, Room 107, Miami, Fla. 33132.
