Legionnaires` Disease
Odds & Sods

TIPSHEET Highlights from the Journals of the American Society for Microbiology


Scientists at the Fairfield Hospital in Australia and the VA Medical Center in Pittsburgh report what they believe to be the second case ever of illness caused by a recently discovered bacterium. The study appears in the July 1997 issue of the Journal of Clinical Microbiology.

The report describes the case of 75-year-old Australian man who came to the hospital after 3 days of fever, chills, sweats, lethargy and anorexia. An initial treatment with antibiotics did not improve his condition, but after changing the antibiotics his condition improved and he recovered. Laboratory tests indicated that the organism that caused his fever was a recently described bacterium known as Desulfovibrio fairfieldensis.

Desulfovibrio bacteria are commonly found in nature and can be isolated from most water and soil types. They are anaerobic, meaning they can only grow in the absence of oxygen. Only five cases of human infection by Desulfovibrio have ever been described and this case represents only the second by this species.

"Laboratories need to be aware of the anaerobic, motile, vibrioid-like organisms, in particular Desulfovibrio species, as rare causes of human disease," say the researchers.
(R. McDougall, J. Robson, D. Paterson, and W. Tee. 1997. Bacteremia caused by a recently described novel Desulfovibrio species. Journal of Clinical Microbiology. 35:1805-1808.)


A bacterium from the Legionella family, not previously associated with human disease, has been identified as the cause of pneumonia in a woman in France. Researchers from the Hopital Paul Brousse in Villejuif, France, report this first case in the July 1997 issue of the Journal of Clinical Microbiology.

The researchers report on a 34-year-old woman who, 4 weeks after a liver transplant, developed severe pneumonia. She suffered neurological deterioration and eventually went into a coma. After several weeks of various antibiotic treatments and a second liver transplant, she recovered.

The cause of her pneumonia was found to be the bacterium Legionella parisiensis. This bacterium was first identified in a cooling tower in Paris in 1985 and since then no further isolations of this organism have been reported until this case. The family Legionellaceae comprises 42 species among which 18 have been isolated from patients with pneumonia. The most well known species is Legionella pneumophila, the cause of Legionnaire's disease, which accounts for nearly 90% of Legionella infections.
(F.L. Presti, S. Riffard, F. Vandenesch, M. Reyrolle, E. Ronco, P. Ichai, and J. Etienne. 1997. The first clinical isolate of Legionella parisiensis from a liver transplant patient with pneumonia. Journal of Clinical Microbiology. 35:1706-1709.)


Nursing and Residential care home owners will be sent a free purpose designed leaflet by the Health and Safety Executive (HSE) to help them control the risk of their patients and residents developing potentially fatal Legionnaires' Disease. The decision to produce the leaflet - Controlling Legionella in Nursing and Residential Care Homes - is the result of a recent survey carried out by the HSE. It showed that many home owners and managers were unaware of the existing HSE guidance on Legionella control, despite the fact that owners and managers of these homes have a legal duty to assess the risks to patients and residents from Legionella and adopt appropriate precautions. The leaflet, based on existing HSE guidance, offers managers clear and simple practical guidance on the steps they need to take to control the risks from Legionella - the bacteria which causes Legionnaires' Disease . The simplest and most effective control, which is accepted internationally, is to keep water hot enough to kill the bacteria. HSE guidance recommends that hot water should be stored above 60 degsC and distributed at above 50 degsC but it also emphasises that managers need to take appropriate precautions to avoid scalding elderly and vulnerable patients and residents. The best way of minimising the scalding risks to such people - who may be disabled or unaware of the danger - is to fit inexpensive thermostatic mixing valves to bath taps and showers. Before producing the leaflet HSE consulted widely with local authorities, representatives of nursing homes and asked for expert opinion from a joint HSE/Department of Health group on Legionellosis. Copies of Controlling Legionella in Nursing and Residential Care Homes, IND(G)253L are available from HSE Books, PO Box 1999, Sudbury, Suffolk, CO10 6FS, tel: 01787-881165 or fax: 01787-313995. Notes to Editors 1. The Legionella bacterium can cause a range of illnesses, commonly known as Legionnaires' Disease, including fatal pneumonia. Elderly people are particularly vulnerable to developing Legionnaires' Disease. The bacteria occur commonly in natural and artificial water systems. They can survive at low temperatures and thrive at temperatures between 20 degs and 50 degsC. They are killed at higher temperature and this is the main method used for their control in domestic water systems. 2. A survey of nursing and residential care homes was carried out by HSE and Local Authority Inspectors in June and July 1996. A questionnaire asking for details of the hot water system and measurement of bath outlet temperature was completed by the inspector as part of normal inspection visits. 3. Scalding is a significant risk nursing and residential care homes. There have been over 30 fatal accidents to patients or residents in such homes the last 10 years and more than 40 other major scalding accidents. 4. The results of the survey are being presented at the 3rd International Conference on occupational health for healthcare workers in Edinburgh (29 June - 2 July). 5. The Joint HSE/DH working group on legionellosis consists of officials from HSE, Department of Health, Department of Environment, Department of Energy, Welsh Office and the Health and Safety Authority Northern Ireland; scientists and experts from the Public Health Laboratory Service, the Centre for Applied Microbiology and Research, Porton Down and Thames Water, all of whom have a direct interest and considerable practical experience in various aspects of Legionella and its control.

Isolation of Legionella pneumophila from the cold water of hospital ice machines:

A previously unrecognized reservoir for L. pneumophila within the hospital environment, ie, the cold water dispensers of hospital ice machines. The cold water dispensers of 14 ice machines were cultured monthly over a 1-year period. Positive cultures were obtained from 8 of 14 dispensers, yielding from 1 to 300 CFU/plate. We were able to link the positivity of these cold water sites to the incoming cold water supply by recovering
L. pneumophila from the cold water storage tank, which is directly supplied by the incoming municipal water line.
This was accomplished by a novel enrichment experiment designed to duplicate the conditions (temperature, sediment, stagnation, and continuous seeding) of the hot water system. Our data indicate that significant contamination of cold water outlets with L. pneumophila can occur. Although no epidemiologic link to disease was made, the fact that the primary source of a patient's drinking water is from the ice machines warrants further investigation of these water sources as possible reservoirs.
(Stout JE; Yu VL; Muraca P Source Infect Control, 1985 Apr, 6:4, 141-6 )

Risk factors for domestic acquisition of legionnaire`s disease.

Legionnaires` disease is a common cause of adult pneumonia. Outbreaks of legionnaires disease have been well described, but little is known about sporadically occurring legionnaires disease, which accounts for most infections. Exposure to contaminated residential water sources is I plausible means of disease acquisition. METHODS: Employing a matched case-control study design in 15 hospitals in 2 Ohio counties, we prospectively enrolled 146 adults diagnosed as having nonepidemic, community-acquired legionnaires disease and compared each with 2 hospital-based control patients, matched for age, sex, and underlying illness category. An interview regarding potential exposures was followed by a home survey that included sampling residential sources for Legionella. Interview and home survey data were analyzed to estimate the risk of acquiring legionnaires disease associated with various exposures. RESULTS: Multivariate analysis showed that a nonmunicipal water supply (odds ratio [OR], 2.26; 95% confidence interval [CI], 1.17-4.37), recent residential plumbing repair (OR, 2.39; 95% CI, 1.10-5.18), and smoking (OR, 3.48; 95% CI, 2.09-5.79) were independent risk factors for legionnaires disease. Univariate analysis suggested that electric (vs gas) water heaters (OR, 1.97; 95% CI, 1.10-3.52), working more than 40 hours weekly (OR, 2.13; 95% CI, 1.12-4.07), and spending nights away from home before illness (OR, 1.68; 95% CI, 1.03-2.74) were additional possible risk factors.
Lower chlorine concentrations in potable water and lower water heater temperatures were associated with residential Legionella colonization.
CONCLUSIONS: A proportion of sporadic cases of legionnaires` disease may be residentially acquired and are associated with domestic potable water and disruptions in residential plumbing systems. Potential strategies to reduce legionnaires` disease risk include consistent chlorination of potable water, increasing water heater temperatures, and limiting exposure to aerosols after domestic plumbing repairs.
(Straus WL; Plouffe JF; File TM Jr; Lipman HB; Hackman BH; Salstrom SJ; Benson RF; Breiman RF Address Division of Bacterial and Mycotic Infections, Centers for Disease Control and Prevention, Atlanta, Ga, USA. Source Arch Intern Med, 1996 Aug 12-26, 156:15, 1685-92 )

Potable water as a source of Legionnaires` disease.

A three-year epidemic of legionnaires` disease in a hospital was dramatically curtailed following hyperchlorination of the potable water supply. The hypothesis that potable water was the source for the outbreak was further supported by isolation of Legionella pneumophila (the agent of legionnaires' disease) from the hospital water supply, observation that a sudden upsurge had occurred in the number of cases following a peculiar manipulation of the hospital water system, and documentation of a 30-fold increase in concentration of organisms in the water when this manipulation was artificially recreated. Thus, potable water may be an important source of epidemic legionnaires' disease and continuous hyperchlorination a method of control.
(Shands KN; Ho JL; Meyer RD; Gorman GW; Edelstein PH; Mallison GF; Finegold SM; Fraser DW Source JAMA, 1985 Mar 8, 253:10, 1412-6)

Investigating a single case of Legionnaires` disease:

Guidance for consultants in communicable disease control.
When a single case of legionnaires' disease is reported, it should be investigated to check whether or not it is linked to other cases or part of an outbreak. The investigation includes confirmation of the diagnosis, tracing the patient's movements during the incubation period, and reporting the case to the National Surveillance Scheme for Legionnaires' Disease at the PHLS Communicable Disease Surveillance Centre. If no common factors are identified between the cases and other cases reported previously, no further action is usually required, unless it is suspected that the infection was acquired in hospital. In these circumstances, the individual case and the hospital's water maintenance programme should be reviewed, and a search made for associated cases, because hospital patients are particularly susceptible to infection. Further steps may be necessary if the link with the hospital is confirmed.
(Saunders CJ; Joseph CA; Watson JM Source Commun Dis Rep CDR Rev, 1994 Sep 16, 4:10, R112-4)


In 1995, 98 cases of Legionella pneumonia were notified, as against 89 in 1994. The diagnosis was laboratory-confirmed in 87 cases, and in 11 cases the laboratory findings supported the suspicion of Legionella pneumonia. Twenty-five cases were confirmed by culture; 22% of notified cases were associated with travel, 25% were probably nosocomial and 53% were community- acquired in Denmark. Cases were notified from counties throughout the country. No evidence of clustering was observed. Patients were aged 18-92 years (median age 60 years), and 63% were men. Information on fatalities is not collected systematically, but 23 deaths in connection with the infection were reported. The median age for the 22 travel-associated cases,was 49 years, and 73% were men. The majority of patients (16) had travelled in Mediterranean countries. Three previously healthy persons aged 42,45 and 54 years died. Cases are regarded as travel-associated if the illness starts within 10 days of returning. Most travel-associated cases are seen in the months of September and October. In 24 cases the infection was presumably hospital-acquired; 14 of these were classified as nosocomial and 10 as possibly nosocomial. They were mostly elderly patients admitted to hospital with other conditions, and were mainly recently operated, such as transplant patients and patients with chronic or malignant disease. At least 10 of these patients died.

Fifty-two patients were thought to have been infected outside a hospital in Denmark; of these, 18 were previously well, while the remainder had chronic illnesses. The cases were evenly distributed throughout the country, with an age range of 18-84 years. In 4 cases a probable source of infection was stated: a hot water tank with stagnant water over an extended period (2), cleaning an old hot water system (1), and a spa-pool (1). In addition, there was an outbreak of Pontiac fever which affected 13 patients. The source of infection was probably a whirlpool. Pontiac fever is an influenza-like illness without pneumonia and is not notifiable in Denmark.

(PRoMED-mail 28 FEBUARY 1997)


The Taiwanese health department last wednesday (11June) issued a warning on th esurge of Legionnaires` disease that had produced almost twice as many cases in the first five months of 1997 as the total number of cases in 1996, 81 cases January to May as 44 cases in 1996.also this year`s outbreak is affecting persons under the age of 25. One patient was only four years old,

The health department is urging people to keep their living space clean and also their Airconditoining systems.

JUNE 20 1997
Communicable Disease Report

Legionella and the European Council for Package Travel

The recently implemented European Council Directive for Package Travel makes tour operators responsible for the acts and omissions of their suppliers. Tour operators can be held 1iable if they knowingly place clients In hotels that may be associated with legionella lnfection. New procedures have agreed with the Association of British Travel Agents (ABTA) and the Federation of Tour Operators (FTO) for the PHLS to report to them anonymised summary Information on single cases of travel associated legionnaires' disease ln residents of England and Wales. ABTA and FTO will identify tour operators using the hotels at which cases have stayed. The tour operators will then remind managers of the hotels - on the understanding, however, that a single case does not mean the hotel was necessarily the source of infection - to check that their water and cooling systems are being maintained to appropriate standards to mimimise any risk of legionella infection. The European Surveillance Scheme for Travel Associated Legionnaires' Disease (EWGLl) , which is coordinated by the PHLS Communicable Disease United Kingdom: Surveillance Centre (CDSC) , wlll lnform ABTA and FTO when they detect travel associated clusters (two or more cases linked to the same accommodatlon arising within a six month period). The information will enable tour operators to make informed decisions on whether they wish to continue using hotels that might present a health risk to their clients.
Two clusters of travel assoclated legionnaires' disease recently reported to CDSC have provided the first opportunity to use the new procedures.
In the first cluster, two people who stayed at a hotel in Marmaris, Turkey in May 1996 acquired legionnaires' disease. The same hotel was associated with another two cases ln September 1995. EVVGLI collaborators, the World Health Organisatlon in the United Kingdom: (WHO) , and the Department of Health who were alerted to the cluster and ABTA monthly report and FTO were sent summary lnformation. Tour operators from the United Kingdom have withdrawn cilents from the hotel whlle public health officials investigate possible sources of lnfection.

The second eluster was associated with an apartment block In Cala Galdana, Minorca where three cases of legionnaires' disease had stayed in the ten days before becoming ill ln May. Within 24 hours of being sent summary informatlon, the tour operator with sole use of the apartment block had withdrawn all its clients to alternative accommodation. Investigations by local public health officials have shown that the outbreak may have been caused by the installation of a new hot water system at the hotel during the first three weeks of May.
Prompt communications from EWGLI, swift withdrawal of clients from implicated hotels, and the rapid launch of lnvestigations by local public health officials should contribute to improved control and prevention of cases and outbreaks of legionnaires' disease linked to package travel.

Rhode Island

Association of Legionnaires' disease with construction:

Two cases of nosocomial legionellosis and discuss the epidemiology of this infection. DESIGN: Potable water was collected from multiple sites. Patient and environmcntal isolates were characterized by the Legionella slide agglutination test and monoclonal anlibody subtyping. Concordance among isolates was conlirmed by pulsed-field get electrophoresis (PFGC). SETTlNG: A 713-bed universily-affliated hospital.
There was widespread contamination of potable water with Legionella pneumophila during a period of major construction; cooling towers were without growth of Legionella. One patient's isolate was the same by PFGC as the environmental isolate collected trom thc water laucet in his room. Control measures included superheating water used in all paticnt carc areas to 75 degrecs C for 72 hours and flushing super heated water through faucets and showers; cleaning shower heads with a sonicator washer; and raising the hot water storage tank temperature from 43 degrees C to 52 degrees C. Afier these interventions, repeat environmental cultures over the next 6 months were without growth of Legionella, and no further cases of nosocomial legionnaires' disease were documented. An association between legionnaires' disease and construction is postulated. Heightened surveillance and preventive measures may be warranted during periods of excavation on hospital grounds or when potable water supplies are otherwise shut down and later repressurized.
Mermel LA; Josephson SL; Giorgio CH; Dempsey J; Parenteau S Department of Medicine, Rhode Island Hospital, Providcnce 02903, USA. Infect Control Hosp Epidemrol, 16: 2, 1995 Feb, 76-81

Legionnaires` disease in Missouri
a review of five sporadic cases.

(Misra DP, Maltby JD, Hurst DJ Mo Med 77 (10): 607-613 (Oct 1980)