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This paper provides one of the first assessments of the burden of both the public health investigation and the economic costs associated with an apparent outbreak of Legionnaires' disease (LD) in South East London. In addition to epidemiological, microbiological and environmental investigations, we collected data on the staff time and resources committed by the 11 main organizations responsible for managing the outbreak. Of the overall estimated costs of 455,856 pounds, only 14% (64,264 pounds) was spent on investigation and control of the outbreak compared with 86% (391,592 pounds) spent on the hospital treatment of the patients. The time and money spent on public health services in this investigation appear to represent good value for money considering the potential costs of a major outbreak, including the high case-fatality rate in LD generally and the high health-care costs. Further research is needed to determine optimum strategies for the cost-effective use of health system resources in investigations of LD. Whether the threshold for investigation of cases should be based on observed incidence rates or the cost-effectiveness of investigations, or both, should be debated further.

We carried out a study in five London paediatric intensive care units (PICUs), with the objectives of describing a cohort of infants with respiratory syncytial virus (RSV) infection, comparing hospital diagnosis with PCR results and investigating the spread of RSV in families. Eligible infants were under 5 months old and admitted betweem November 1998 and October 1999 with respiratory failure, apnoea and/or bradycardia or acute life threatening episodes (ALTE). We diagnosed RSV by PCR analysis of nasopharyngeal aspirate, and in contacts by PCR of pernasal swabs. Of the 137 eligible infants, 66% (91/137) were recruited; of these, 82% (75/91) had RSV, with 47% (35/75) diagnosed by hospital laboratory tests and 93% (70/75) by PCR. The median duration of ventilation was 4.4 days, the length of stay on PICU, 8.6 days, and the length of stay in hospital, 15.9 days. In most families (62%), the parents and siblings developed symptoms of RSV infection at the same time as the infant. When the index infant was a secondary case, primary cases occurred in both older siblings (16 families) and adults (11 families). Silent RSV infection occurred frequently amongst children and adults. RSV is under-diagnosed in PICUs. PCR increases the rate of diagnosis of RSV compared to routine hospital diagnostic methods. Young infants are most often infected at the same time as or before their parents and siblings, indicating that the source may be outside the household; vaccinating family members may not prevent RSV infection in infants.

Background: An outbreak of legionnaires' disease occurred in central London in January and February 1989. An Infection Control Committee was established to investigate the outbreak and institute control measures. The objective of this paper is to describe the investigation and control of the outbreak., Methods: An epidemiological survey and case-control study were carried out. The subjects were cases of community acquired pneumonia associated with central London with onset of illness in January and February 1989., Results: Thirty-three confirmed cases, including five deaths, and ten suspected cases, including three deaths, were identified with dates of onset from 1 January to 11 February. A clustering of visits by cases to the vicinity of Piccadilly Circus was noted, and a case-control study demonstrated a strong association between illness and visits to this area in the two weeks before onset of symptoms. The causative organism, Legionella pneumophila serogroup 1, was isolated from six patients. Legionella pneumophila of the same serogroup was isolated from water samples from five wet cooling systems (cooling towers) in the area under investigation, but in only two systems was the organism indistinguishable by subtyping from the patients' strains. Many of the cooling towers examined were inadequately maintained, including one of the two above a building adjacent to Piccadilly Circus from which a strain indistinguishable from the outbreak strain was isolated. All cooling towers in the area were shut down until inspected, and only allowed to restart after appropriate maintenance had been instigated., Conclusions: This outbreak showed the continuing risk of legionnaires' disease posed by wet cooling systems, including cooling towers, and highlighted the need to assess this risk so that appropriate maintenance is carried out. Regulations have recently been introduced, under the Health and Safety at Work Act, requiring notification of all wet cooling systems to the local authority to facilitate the investigation of outbreaks of legionnaires' disease.

Infection with Legionella is often encountered in immunosuppressed patients, especially in recipients of renal allografts. From January 1985 until April 1993 14 cases of nosocomial legionella pneumonia were diagnosed (four by culture, 10 by serological methods) on the surgical transplantation unit of Innsbruck University Hospital. All isolates from patients and from the building's hot water were found to be Legionella pneumophila serogroup 1. They were indistinguishable from each other by monoclonal antibody subtyping and restriction fragment length polymorphism pattern and thus indicated a series of infections originating from the same source during a period of more than 8 years. Repeated efforts to control Legionella by raising the temperature in the hot water lines failed to bring permanent success. Replacing the central hot water supply with small electric water heaters installed in the patient rooms on the transplant ward now seems to have reduced the incidence of legionellosis on this unit. However, further infections occurring in transplant patients in other surgical departments in the same building indicate that a major renovation of the whole surgical building's hot water system is necessary.