Harper D. Minimising the spread of Legionnaires' disease--a programme designed to prevent incubation of LP in hospital water and air conditioning systems. Hosp Eng. 1984 Mar;38(3):5-9. PMID: 10265811.
O'Mahony M, Noah ND, Evans B, Harper D, Rowe B, Lowes JA, Pearson A, Goode B. An outbreak of gastroenteritis on a passenger cruise ship. J Hyg (Lond). 1986 Oct;97(2):229-36. doi: 10.1017/s0022172400065311. PMID: 3537115; PMCID: PMC2083547.'
In an outbreak of gastroenteritis on board a cruise ship 251 passengers and 51 crew were affected and consulted the ship's surgeon during a 14-day period. There was a significant association between consumption of cabin tap water and reported illness in passengers. Enterotoxigenic Escherichia coli were isolated from passengers and crew and coliforms were found in the main water storage tank. Contamination of inadequately chlorinated water by sewage was the most likely source of infection. A low level of reported illness and late recognition of the outbreak delayed investigation of what was probably the latest in a series of outbreaks of gastrointestinal illness on board this ship. There is a need for a national surveillance programme which would monitor the extent of illness on board passenger cruise ships as well as a standard approach to the action taken when levels of reported illness rise above a defined level.
Colbourne JS, Pratt DJ, Smith MG, Fisher-Hoch SP, Harper D. Water fittings as sources of Legionella pneumophila in a hospital plumbing system. Lancet. 1984 Jan 28;1(8370):210-3. doi: 10.1016/s0140-6736(84)92126-3. PMID: 6141347.
An extensive study of the plumbing systems in Kingston Hospital was made over the three years following the 1980 outbreak of legionnaires' disease. The introduction of chlorination and raising the water temperature controlled the outbreak but failed to decontaminate water outlets in the wards. Legionella pneumophila was isolated from rubber washers in shower fittings, and laboratory experiments demonstrated the ability of L pneumophila to grow in water in contact with these rubber components. All the components in the hospital's fittings were replaced with an approved type, and since then L pneumophila has not been isolated from water or components.
O'Mahony M, Lakhani A, Stephens A, Wallace JG, Youngs ER, Harper D. Legionnaires' disease and the sick-building syndrome. Epidemiol Infect. 1989 Oct;103(2):285-92. doi: 10.1017/s0950268800030648. PMID: 2680548; PMCID: PMC2249498.
In October 1985, six cases of legionnaires' disease were associated with a police headquarters building. Four were amongst staff who worked in or visited the communications wing of the headquarters and two cases occurred in the local community. A case-control study implicated the operations room of the communications wing as the main area associated with infection. This wing was air- conditioned and smoke tracer studies showed that drift from the exhaust as well as from the base of the cooling tower entered the main air-intake which serviced the air- conditioning system. Legionella pneumophila serogroup 1 subgroup pontiac was isolated from water and sludge in the cooling tower pond. Contaminated drift from the top of the cooling tower was probably responsible for the two community cases. An additional discovery was that symptoms suggestive of the sick-building syndrome were associated with working in this wing.
O'Mahony MC, Stanwell-Smith RE, Tillett HE, Harper D, Hutchison JG, Farrell ID, Hutchinson DN, Lee JV, Dennis PJ, Duggal HV, et al. The Stafford outbreak of Legionnaires' disease. Epidemiol Infect. 1990 Jun;104(3):361-80. doi: 10.1017/s0950268800047385. PMID: 2347381; PMCID: PMC2271767.
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.'
Hunt DA, Cartwright KA, Smith MC, Middleton J, Bartlett CL, Lee JV, Dennis PJ, Harper D. An outbreak of Legionnaires' disease in Gloucester. Epidemiol Infect. 1991 Aug;107(1):133-41. doi: 10.1017/s0950268800048767. PMID: 1879480; PMCID: PMC2272039.
Fourteen people living in or near the city of Gloucester fell ill with Legionnaires' disease caused by Legionella pneumophila serogroup (SG) 1 between 27 August and 27 October 1986. Another patient had fallen ill on 30 May. Nine of the 15 were diagnosed retrospectively during a case finding exercise. There were three deaths. Three cases of Pontiac fever were also diagnosed. The source was probably one or more wet cooling towers. Nineteen premises in the city with such towers were identified, and three just outside Gluocester. Samples from 11 of the 22 premises grew Legionella spp.; from nine of these L. pneumophila SG 1 (Pontiac) was isolated. The efficacy of regular addition of biocide in addition to hypochlorite added at the time of disinfection in inhibiting the growth of Legionella spp. was demonstrated. A survey of patients' movements during their likely incubation period showed that there was no single building that all patients had visited, but there were two areas of the city which nearly all had visited or passed through by car. A case- control study demonstrated an association with one of these areas. Cooling towers near both areas may have been sources but the evidence is insufficient to incriminate any single one. The unexpected finding of L. pneumophila SG 1 (Pontiac) in nine towers supports the hypothesis that there may have been multiple sources. Cooling towers may have been contaminated by mains water or by drift from other towers.
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