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Pontiac fever outbreak associated with a cooling tower
Abstract:
In late April 1984, an outbreak of Pontiac fever was investigated in an office building in lower Manhattan (New York City). The outbreak was characterized by a high attack rate (78 per cent overall); the predominant symptoms were myalgias, chills, fatigue, fever, and headache. There was a clustering of cases in an office that was air cooled by a dedicated cooling tower separate from the remainder of the building. A high concentration of live L. Pneumophila cells in the cooling tower was quantified. Airborne spread via settle plates placed along the air intake system and within the office was demonstrated. Legionella pneumophila serogroup 1 antigen was found in the urine of two cases, and identical monoclonal antibody reactivity patterns of isolates from all sources was observed. Difficulty was experienced in eliminating the organism from the tower.
Insights
An investigation into a Pontiac fever outbreak in a New York City office building revealed airborne spread of Legionella pneumophila from a cooling tower, causing widespread illness.
Area of Science:
- Environmental microbiology
- Public health
- Infectious disease epidemiology
Background:
- Pontiac fever is a mild, flu-like illness caused by Legionella bacteria.
- Outbreaks are often linked to contaminated water systems, particularly cooling towers.
- Identifying the source and transmission route is crucial for preventing further spread.
Purpose of the Study:
- To investigate the cause and transmission of a Pontiac fever outbreak in a Manhattan office building.
- To identify the specific pathogen and its environmental source.
- To assess the effectiveness of control measures.
Main Methods:
- Epidemiological investigation including case finding and symptom analysis.
- Environmental sampling of the building's cooling tower and air intake system.
- Microbiological analysis of water and air samples for Legionella pneumophila.
- Serological testing and monoclonal antibody typing of bacterial isolates.
Main Results:
- A high attack rate (78%) of Pontiac fever was observed among building occupants.
- Legionella pneumophila serogroup 1 was identified in high concentrations in the dedicated cooling tower.
- Airborne transmission was confirmed via settle plates in the air intake and affected office.
- The organism was difficult to eradicate from the cooling tower.
Conclusions:
- The office building's cooling tower was the source of the Pontiac fever outbreak.
- Airborne dissemination from the cooling tower led to widespread infection.
- Effective disinfection and maintenance are critical for preventing Legionella outbreaks in building water systems.