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Legionellosis: a new disease of Western hemisphere?
1University Hospital Antwerp Laboratory for Microbiology, Wilrijkstraat 10-B-2650 Antwerpen.
Abstract:
Legionnaires' disease is an acute bacterial pneumonia caused by an organism of the family of Legionellaceae. L. pneumophila serotype 1 is responsible for most infections. The incidence of Legionnaires' disease in Belgium is not known because the diagnosis cannot be made based on clinical or radiological grounds and because there is a microbiological underdiagnosis. Legionellae are widely distributed in nature, as free living organisms, in protozoa, and in biofilms. As a consequence, these bacteria are particularly resistant to disinfection and heating. We recently investigated an outbreak of legionnaires' disease among visitors to a fair in Kapellen, Belgium. The annual commercial fair at Kapellen was held between October 29 to November 7, 1999. Ninety-three people, who met the case definition, were identified. Among these 93 patients, 41 could be considered as confirmed cases, 14 as presumptive, and 38 as possible cases. Five patients died in as a consequence of the epidemic. A case-control study showed a causal link between a visit to the fair and the occurrence of the infection. A contaminated aerosol from a whirlpool was probably responsible for the outbreak. This epidemic illustrates the need for preventive measures to control for the growth of Legionellae in aerosol producing instruments.
Insights
An outbreak of Legionnaires' disease in Belgium was linked to a fair. A contaminated whirlpool aerosol was the likely source, highlighting the need for preventive measures against Legionellae bacteria.
Area of Science:
- Public Health
- Infectious Diseases
- Bacteriology
Background:
- Legionnaires' disease is an acute bacterial pneumonia caused by Legionellaceae.
- Legionella pneumophila serotype 1 is the most common cause of infection.
- Diagnosis is challenging due to non-specific clinical and radiological findings, leading to underdiagnosis.
Purpose of the Study:
- To investigate an outbreak of Legionnaires' disease among visitors to a fair in Kapellen, Belgium.
- To identify the source and contributing factors of the outbreak.
- To emphasize the importance of preventive measures.
Main Methods:
- Case identification based on a defined case definition.
- Classification of cases into confirmed, presumptive, and possible.
- A case-control study to establish a link between the fair visit and infection.
Main Results:
- Ninety-three individuals met the case definition, with 41 confirmed cases.
- Five fatalities occurred as a consequence of the epidemic.
- A case-control study confirmed a causal link between fair attendance and infection; a contaminated whirlpool aerosol was implicated.
Conclusions:
- The outbreak demonstrated a significant public health risk associated with aerosol-producing instruments.
- Preventive strategies are crucial to control Legionellae growth in such environments.
- Enhanced surveillance and diagnostic capabilities are needed to understand the true incidence of Legionnaires' disease.