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First report of the Committee of Inquiry into the outbreak of Legionnaires' Disease in Stafford in April 1985

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First report of the Committee of Inquiry into the outbreak of Legionnaires' Disease in Stafford in April 1985
Outbreak of legionnaires' disease in Stafford in April 1985
Committee of Inquiry into the Outbreak of Legionnaires' Disease in Stafford in April 1985
 Badenoch, Sir John; Holland, Christopher; Hannah, D.; O'Grady, F.W.; O'Sullivan, P.E.
Chairman: Badenoch, Sir John

The Committee was set up in urgent response to public concern over an outbreak of Legionnaires' Disease, which occurred suddenly at the District General Hospital (SDGH) in Stafford, in April 1985. The outbreak affected 101 people, of whom 28 died. The Committee was asked to inquire into the cause of the outbreak; to consider the adequacy of measures taken to investigate and to deal with the outbreak; and to report to the Secretary of State for Social Services and make recommendations on any action necessary to reduce the danger of future outbreaks originating in hospitals, other buildings and elsewhere. This first report investigates the cause of the Stafford outbreak and the adequacy of the measures taken to deal with it. It includes recommendations on the medical and engineering aspects of the Committee's investigations. The second report inquires into the broader question, making further recommendations, which have wider implications for air conditioning plant; and for the use of water for industrial and domestic purposes.

Chapters in this report include: the medical services at Stafford; medical background; the outbreak from the patients' and doctors' viewpoints; epidemiology of the outbreak; comments on the medical and microbiological aspects of the outbreak; the history of the SDGH, related to contemporary knowledge of Legionnaires' Disease; the air conditioning system at SDGH; hospital operation and maintenance: HN(80)39 and the Biocide Regime; the outbreak from an engineering viewpoint; the cause of the outbreak; comments on engineering aspects of the outbreak; and recommendations. A short history of ventilation in standard hospital development: a note prepared by DHSS for the Committee of Inquiry is included in the appendices.

A major recommendation made by the Committee is that the extent to which the design of future hospitals should include reliance on air conditioning should be subject to scrutiny and that such air conditioning as is included in the design of future hospitals should not incorporate wet cooling tower systems. A number of other recommendations are made with respect to existing hospitals including giving urgent consideration to replacing any wet cooling tower with an air-cooled system

The Stafford outbreak of Legionnaires' disease.

A large outbreak of Legionnaires' disease was associated with Stafford District General Hospital. A total of 68 confirmed cases was treated in hospital and 22 of these patients died. A further 35 patients, 14 of whom were treated at home, were suspected cases of Legionnaires' disease. All these patients had visited the hospital during April 1985. Epidemiological investigations demonstrated that there had been a high risk of acquiring the disease in the out patient department (OPD), but no risk in other parts of the hospital.
The epidemic strain of Legionella pneumophila, serogroup 1, subgroup Pontiac 1a was isolated from the cooling water system of one of the air conditioning plants. This plant served several departments of the hospital including the OPD. The water in the cooling tower and a chiller unit which cooled the air entering the OPD were contaminated with legionellae. Bacteriological and engineering investigations showed how the chiller unit could have been contaminated and how an aerosol containing legionellae could have been generated in the U-trap below the chiller unit. These results, together with the epidemiological evidence, suggest that the chiller unit was most likely to have been the major source of the outbreak. Nearly one third of hospital staff had legionella antibodies.
These staff were likely to have worked in areas of the hospital ventilated by the contaminated air conditioning plant, but not necessarily the OPD. There was evidence that a small proportion of these staff had a mild legionellosis and that these 'influenza-like' illnesses had been spread over a 5-month period. A possible explanation of this finding is that small amounts of aerosol from cooling tower sources could have entered the air-intake and been distributed throughout the areas of the hospital served by this ventilation system. Legionellae, subsequently found to be of the epidemic strain, had been found in the cooling tower pond in November 1984 and thus it is possible that staff were exposed to low doses of contaminated aerosol over several months. Control measures are described, but it was later apparent that the outbreak had ended before these interventions were introduced. The investigations revealed faults in the design of the ventilation system.
(O'Mahony MC; Stanwell-Smith RE; Tillett HE; Harper D; Hutchison JG; Farrell ID; Hutchinson DN; Lee JV; Dennis PJ; Duggal HV; et; al Address Public Health Laboratory Service Communicable Disease Surveillance Centre, London. Epidemiol Infect, 1990 Jun, 104:3, 361-80)

The World's Worst Outbreak Kills 37 People In England, At The Stafford District General

May 1985

It's unclear what circumstances are necessary for outbreaks to occur. Some hospitals will have Legionella in their cooling tower and will have an outbreak, and others where bacteria have been found will not.
Legionella lives in water. It is transmitted by being inhaled, often in an aerosol like mist, which is why shower heads, water taps and airconditioning cooling towers on hotels and hospitals are usually found to be the breeding ground and source of the infection.

Legionella was found in one of the hospital's five cooling towers. Immediately after the discovery, The hospital's water supply was heavily chlorinated to kill the bacteria.
It has been determined that all the victims were treated as outpatients in the hospitals clinic

LEGIONNAIRES' DISEASE BACTERIA FOUND AT HOSPITAL,

May, 1985

Traces of Legionnaires' Disease bacteria have been found in the airconditioning system of a Stafford hospital where the world's worst known outbreak of the disease has killed 37 people, health officials said yesterday.

In Stafford, a small growth of Legionnaires' bacteria was found in a water sample taken from a cooling tower on the roof of Stafford District General Hospital.

The finding supports the investigators theory that water in the hospital's cooling tower was the source of the outbreak,

Since the first cases were reported at the Stafford hospital on April 22, a total of 163 patients have been treated for symptoms of Legionnaires' Disease at three hospitals in Stafford in central England. Thirty-seven have died, and 28 still are receiving treatment.

May 1985

Test results from the water cooling tower of a hospital suspected to be the source of the largest known outbreak of Legionnaires' Disease have so far proved negative, British health officials said yesterday.

The director general of the Staffordshire Health Authority said that the source of the outbreak that has left 37 people dead in central England still had not been found. The results on water samples so far are negative The samples from the Stafford General District Hospital were taken on May 4, one day after a health team declared that the outbreak in the area was Legionnaires' Disease, a severe form of pneumonia. The cooling towers at the hospital were chlorinated and then switched off that evening.

Since the outbreak first appeared on April 16, 164 people have been admitted to Stafford area hospitals with acute respiratory illness and symptoms that could be Legionnaires' Disease, Doctors are still treating 54 patients.

Of the 37 with Legionnaires' symptoms who have died, 14 are confirmed to have died of Legionnaires' Disease ,So far has positively identified Legionnaires' Disease in 60 patients.
One technician and seven nurses at Stafford District General Hospital have been diagnosed as having Legionnaires' disease.

DOCTORS SAY END IN SIGHT FOR OUTBREAK

May 1985

Health authorities said yesterday that they hoped the outbreak of Legionnaires' Disease that has claimed 37 lives would end in a few days. It is believed to be the world's highest death toll from an outbreak of the virulent illness.

An 80-year-old man died of the pneumonia-like illness yesterday. Two more people with symptoms of the disease were admitted to Stafford District General Hospital, which is believed to have been the source of the infection. Blood tests showed that six nurses who had worked in the outpatient area have the disease bacterium in their bloodstreams.

THE DEATH TOLL RISES IN THE LEGIONNAIRES' DISEASE OUTBREAK
MAY 1985

The Stafford District General Hospital, where a majority of the cases have been treated, is also suspected of being the source of the disease, The Hospital building, which opened in 1983 and cost nearly 30 million to construct.

Since the outbreak here began on the 15 April, 146 patients have been admitted to hospitals in Stafford with symptoms of Legionnaires' disease.

The number of deaths rose to 30 yesterday , but only five have so far been positively identified as caused by Legionnaires' Disease. The other 28 are cases in which the disease is suspected, but not confirmed.

Receptionists at the Staffordshire Health Authority say that their phone lines were so jammed last week that fuses blew out.

a unit engineer at the Stafford hospital, said yesterday that his hunch was that the source was elsewhere. There are lots of places in Stafford that have airconditioning systems supermarkets, factories, power stations

Only 20 of the 31 people positively identified with Legionnaires' Disease have been found to have been in the hospital when they would have contracted the disease

TOLL RISES IN LEGIONNAIRES' DISEASE EPIDEMIC

May 1985

Three more patients have died from Legionnaires'Disease in three separate incidents in widely separated areas of the country,

The death toll from the outbreak of the disease at Stafford District General Hospital rose to 31 with the death of an 82-year-old There have been five new suspected cases this week in the Stafford outbreak. A total of 68 patients are receiving treatment, two of them in intensive care.

LEGIONNAIRES' DISEASE TOLL IN REACHES 30

May 1985

The death toll in England`s largest outbreak of Legionnaires' Disease rose to 30 yesterday, passing the number who died after an outbreak in Philadelphia in 1976,

The latest fatality of the disease, which produces symptoms like pneumonia and is particularly dangerous for old and weak people, was a 60-year-old woman.

Public health authorities announced that they had traced the source of infection to the airconditioning cooling towers on the roof of the Stafford General Hospital, Thousands of people may have been exposed to the bacteria that causes the disease during visits to the hospital clinic.

HOSPITAL IS CALLED SOURCE OF LEGIONNAIRES' DISEASE OUTBREAK

May, 1985

Cooling towers at a hospital are believed to be the source of infection in one of the world's worst outbreaks of Legionnaires' Disease, Twenty-nine people have died so far from the severe pulmonary disease,

At least 121 people in the Stafford area have contracted the disease in less than three weeks, and more than half are still undergoing treatment, The Legionnaire`s bacteria, Legionella pneumophila, was spread by one of the five cooling towers at the hospital, which opened 11 months ago

LEGIONNAIRES' DISEASE TIED TO DEATHS

May 1985

An epidemic of Legionnaires' Disease is believed responsible for the deaths of up to 27 elderly people in Stafford England.

Doctors initially thought the illness was influenza, but 12 cases of Legionnaires' Disease were confirmed yesterday, Three of the deaths had been confirmed as being from Legionnaires' disease and nearly all the others were being blamed on the illness. 117 people with flulike symptoms had been admitted to three Stafford hospitals since the outbreak started about 16 days ago. 69 remained remain in hospital

JUNE 1985

It created a mystery when it killed 29 and affected 182 people who attended the American Legion convention here at the Bellevue Stratford in August 1976.

It was some time later in 1977 that the Centers for Disease Control in Atlanta identified the Bacteria They called it Legionella pneumophila.

Isolated cases of Legionnaires' Disease were buried in the news, The Atlanta center received only spotty reports of Legionnaire`s Disease from hospitals across the country, because, officials believe, many doctors did not think to test for it.

Its back with a vengeance Legionnaires' Disease has killed again.

One of the world's worst-known outbreak killed 28 people in Stafford, England, at the Stafford District General Hospital, after the first cases were reported in April .

Although it may appear that Legionnaires' Disease has suddenly struck after a long period, the fact is the Legionella bacteria have continued to infect and kill people mostly the sick and elderly.

Legionella lives in water. It is transmitted by being inhaled, often in an aerosol-like mist, which is why airconditioning, water taps shower heads,and cooling towers and hospitals are found to be the source of the infection.

In Stafford, investigators found concentrations of Legionella in one of the hospital's five cooling towers. Immediately after the discovery on May 3, the hospital's water supply was heavily chlorinated to kill the bacteria.

Investigators are sure that all the victims were treated as outpatients in the hospitals clinic.

Of the 175 patients who were admitted to the hospital with high fever and tested, 72 positive cases have been identified with the very strain found in the cooling tower, Were still working on the second tests on some of them. Because the Legionnaires' bacteria is very difficult to culture.

The British health minister so far has appointed three members of a five-member investigative panel to find the cause of the outbreak and to determine whether the measures taken to investigate and deal with the outbreak were adequate. The committee will also recommend measures to prevent other outbreaks.

The committee will look particularly closely at whether the hospital's water supply was chlorinated heavily enough, Chlorine prevents the breeding of such organisms.

Legionellosis -- Staffordshire, England, and Wayne County, Michigan

The largest reported outbreak of legionellosis outside the United States occurred during April and early May 1985 in Staffordshire, England. During this period, 158 persons were hospitalized with acute respiratory infections; 36 (23%) of these cases have been fatal. To date, 60 patients have laboratory evidence of legionellosis, including 11 of the fatal cases.
Patients are predominantly elderly, and most reside within an 8-10 mile area. The only common exposure noted among the 50 confirmed cases was a visit to the Outpatient Department (OPD) at the Stafford District General Hospital. A case-control study to confirm this association and to define specific exposures within the OPD is under way.
Most visits to the OPD occurred in the week following Easter vacation. The OPD was not open during the vacation period, and the water supply was not circulating at that time. Samples from the potable water system have been negative for Legionella to date.
There is also a cooling tower from the air conditioning system in the vicinity of the OPD, and L. pneumophila serogroup 1 has been isolated from water samples.
The cooling tower and the potable water system have been chlorinated, and the potable hot water system temperature has also been increased. No further cases have occurred.

An outbreak of legionellosis also occurred in Michigan during early May. Fourteen cases of pneumonia with high fever have been identified in the approximately 380 persons who attended a church banquet at a hotel on April 27; three (21%) of these cases have been fatal.
To date, seven cases have laboratory evidence of legionellosis, including all the fatal cases. No common exposures other than attending the banquet have been identified.
Samples of the hotel's potable water, a nearby swimming pool and whirlpool, and the 12 functioning heat and ventilation air conditioning units have been obtained. Washings obtained from the external surface of the cooling coils of both air conditioning units supplying the banquet hall have grown L. pneumophila serogroup 1.
Passive surveillance of the over 800 persons attending 12 other banquets held at the hotel between April 25 and May 10 has identified only one suspected case with pneumonia. No recent cases have been identified.
Reported by The Communicable Disease Surveillance Center, London, England; KA Tait, MPH, DW Lawrenchuk, MD, V Vangieson, DVM, Wayne County Health Dept, Michigan, WN Hall, MD, KR Wilcox, Jr, MD, Michigan Department of Public Health; Respiratory and Special Pathogens Epidemiology Br, Div of Bacterial Diseases, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note:
Legionnaires' disease occurs in epidemic and sporadic forms. Sporadic cases outnumber the epidemic cases; an estimated 25,000-50,000 cases of sporadic legionellosis occur in the United States each year (1). Despite this, the occurrence of large outbreaks, such as that in Staffordshire, underlines the continuing public health hazard of epidemic legionellosis.
During outbreaks, attack rates tend to be highest in specific high-risk groups, including the elderly, smokers, and immunocompromised persons.

Epidemic legionellosis usually results from exposure of susceptible individuals to an aerosol generated by an environmental source of water contaminated with Legionella. In previous outbreaks, disease has been associated with exposure to evaporative condensers, cooling towers, showers, whirlpools, and respiratory therapy equipment (2-6).
A specific source has not yet been epidemiologically implicated in either of these recent outbreaks. Recovery of Legionella from an environmental site does not by itself constitute proof of the source of the outbreak because Legionella is frequently isolated from water sources unrelated to outbreaks of human disease.
Additional efforts must be made to find an association between exposure to a given potential source of the organism and occurrence of the disease, including appropriate epidemiologic studies, specific sub-typing of Legionella isolates, and identification of a mechanism of aerosol generation that could allow transmission to occur (7).
Further epidemiologic and laboratory investigation of potential environmental sources is currently under way in both outbreaks.

Routine testing of potable water systems or cooling towers for L. pneumophila is of questionable value and, therefore, has not been recommended, since the organism is ubiquitous, and the significance of a positive culture in the absence of associated illness cannot be defined. In addition, routine decontamination of potable water systems or cooling towers specifically directed at Legionella is not without hazard. Routine treatment with biocides active against Legionella does not necessarily eradicate the organism (8). Studies are under way to determine the settings in which Legionella causes human disease and to evaluate effective control measures.

References

Foy HM, Broome CV, Hayes PS, Allan I, Cooney MK, Tobe R. Legionnaires' disease in a prepaid medical-care group in Seattle 1963-75. Lancet 1979;I:767-70.

Dondero TJ, Rendtorff RC, Mallison GF, et al. An outbreak of Legionnaires' disease associated with a contaminated air-conditioning cooling tower. N Engl J Med 1980;302:365-70.

Spitalny KC, Vogt R, Witherell L, et al. Legionnaires' disease and Pontiac fever associated with a whirlpool. Miami Beach, Florida: 22nd Interscience Conference on Antimicrobial Agents and Chemotherapy, 1982 (abstract #87).

Shands KN, Ho JL, Gorman GW, et al. Potable water as a source of Legionnaires' disease. Clin Res 1981;29 (abstract #260A).

Jones E, Checko P, Dalton A, et al. Nosocomial Legionnaires disease associated with exposure to respiratory therapy equipment, Connecticut. In: Legionella. Thornsberry C, Balows A, Feeley JC, Jakubowski W, eds. Washington D.C.: ASM, 1984:225-7.

Cordes LG, Wiesenthal AM, Gorman GW, et al. Isolation of Legionella pneumophila from hospital shower heads. Ann Intern Med 1981;94:195-7.

Broome CV. Epidemiologic assessment of methods of transmission of legionellosis. Zbl Bakt Hyg, I. Abt. Orig. A 1983;255:52-7.

Fliermans CB, Harvey RS. Effectiveness of 1-Bromo-3-Chloro-5, 5-Dimethylhydantoin against Legionella pneumophila in a cooling tower. Applied Environ Microbiology. 1984;47:1307-10.

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