RESUMEN
We report the investigation of a community-acquired outbreak of Legionnaires' disease. An epidemiological, environmental, and meteorological investigation was undertaken. Fifty-five cases were reported in October and November 2005. The exposure occurred in a large area, with 12 cases (21.8%) located between 1,800 and 3,400 metres from the source. Water sample cultures showed that Legionella pneumophila serogroup 1 (Lp-1) was present in five cooling towers in two industrial locations in Gurb (plants A and B). Two Lp-1 strains were recovered from plants A and B, but only Lp-1 strains from plant A showed a pulsed-field gel electrophoresis (PFGE) profile identical to those obtained from three of the cases. Inspection of the cooling towers in plant A revealed inadequate maintenance. Weather conditions in October 2005, with mostly high temperatures and high humidity, together with the flat terrain could have been favouring factors. This study showed a community outbreak from a cooling tower as a common source in a large area. Climate and terrain could explain the dissemination of contaminated aerosols.
Asunto(s)
Infecciones Comunitarias Adquiridas/epidemiología , Brotes de Enfermedades , Legionella pneumophila/aislamiento & purificación , Enfermedad de los Legionarios/epidemiología , Adulto , Anciano , Anciano de 80 o más Años , Microbiología del Aire , Infecciones Comunitarias Adquiridas/etiología , Infecciones Comunitarias Adquiridas/microbiología , Electroforesis en Gel de Campo Pulsado , Femenino , Humanos , Legionella pneumophila/genética , Enfermedad de los Legionarios/etiología , Enfermedad de los Legionarios/microbiología , Masculino , Persona de Mediana Edad , Modelos Estadísticos , Distribución Normal , Factores de Riesgo , España , Encuestas y Cuestionarios , Microbiología del Agua , Tiempo (Meteorología)RESUMEN
This paper reports the investigation of a community-acquired outbreak of Legionnaires' disease in the municipalities of Vic and Gurb (Central Region of Catalonia, Spain). There were 55 cases reported in October and November 2005. An epidemiological and environmental investigation was undertaken. Thirty-five case patients (64%) lived in Vic or Gurb, while 36% had visited or worked in Vic or Gurb during the 10 days before onset of symptoms, but no commonly frequented building could be identified. Water probes for culture were obtained from 30 cooling towers. In five cooling towers of two industrial settings in Gurb (plants A and B), Legionella pneumophila (Lp) serogroup 1 was present. Two Lp-1 strains were recovered from cooling towers in plants A and B. The Lp-1 strain from plant A showed a PGFE profile identical with those obtained from three patients. The exposure to Legionella pneumophila apparently occurred in a large area, since 43 of the 55 cases lived, visited or worked within a distance of 1,800 m from plant A, and six cases in a distance between 2,500 and 3,400 m. The inspections of cooling towers in plant A revealed inadequate disinfectant doses of biocide, non-existent maintenance records on weekends and wrong sample points for routine microbial check-ups. Weather conditions in October 2005 template temperature and high humidity (wind conditions are unappreciable) could have been favourable factors in this outbreak together with the flat terrain of Gurb and Vic area, explaining the extensive horizontal airborne dissemination of contaminated aerosols. The outbreak could have been prevented by proper and correct maintenance of the cooling tower at plant A.
Asunto(s)
Brotes de Enfermedades/estadística & datos numéricos , Enfermedad de los Legionarios/epidemiología , Vigilancia de la Población , Medición de Riesgo/métodos , Estaciones del Año , Adulto , Infecciones Comunitarias Adquiridas/epidemiología , Infecciones Comunitarias Adquiridas/prevención & control , Femenino , Humanos , Incidencia , Enfermedad de los Legionarios/prevención & control , Masculino , Persona de Mediana Edad , Factores de Riesgo , España/epidemiologíaRESUMEN
A community outbreak of Legionella pneumonia in the district of Cerdanyola, Mataró (Catalonia, Spain) was investigated in an epidemiological, environmental and molecular study. Each patient was interviewed to ascertain personal risk-factors and the clinical and epidemiological data. Isolates of Legionella from patients and water samples were subtyped by pulsed-field gel electrophoresis. Between 7 August and 25 August 2002, 113 cases of Legionella pneumonia fulfilling the outbreak case definition criteria were reported, with 84 (74%) cases being located within a 500-m radius of the suspected cooling tower source. In this area, the relative risk of being infected was 54.6 (95% CI 25.3-118.1) compared with individuals living far from the cooling tower. Considering the population residing in the Cerdanyola district (28,256 inhabitants) as a reference population, the attack rate for the outbreak was 399.9 cases/100,000 inhabitants, and the case fatality rate was 1.8%. A single DNA subtype was observed among the ten clinical isolates, and one of the subtypes from the cooling tower matched exactly with the clinical subtype. Nine days after closing the cooling tower, new cases of pneumonia caused by Legionella ceased to appear. The epidemiological features of the outbreak, and the microbiological and molecular investigations, implicated the cooling tower as the source of infection.
Asunto(s)
Brotes de Enfermedades , Legionella pneumophila/aislamiento & purificación , Enfermedad de los Legionarios/epidemiología , Microbiología del Agua , Adulto , Aerosoles , Anciano , Aire Acondicionado/instrumentación , Infecciones Comunitarias Adquiridas/epidemiología , Infecciones Comunitarias Adquiridas/microbiología , Femenino , Humanos , Legionella pneumophila/genética , Enfermedad de los Legionarios/diagnóstico , Masculino , Persona de Mediana Edad , Factores de Riesgo , España/epidemiologíaRESUMEN
In August 2002 an outbreak of Shigella sonnei infection occurred in a Spanish town of 6343 inhabitants. In total, 756 people developed acute gastroenteritis and 181 cases were shigella-confirmed. The peak incidence was during 5-6 August 2002. The estimated primary attack rate was 9.97%; the attack rate for secondary cases was 38%. The <15 years ago group was most affected (16.49%). The town and its surroundings were served by two water systems, A and B. The cases had consumed water provided by system A (attack rate 164 cases/1000 population). Microbiological analysis of water from system A did not show the presence of coliform bacteria or shigella. This shigellosis outbreak was the largest reported in Spain. The impact of the epidemic was probably greater than the incidence detected.
Asunto(s)
Disentería Bacilar/epidemiología , Gastroenteritis/epidemiología , Shigella sonnei , Microbiología del Agua , Abastecimiento de Agua/normas , Adolescente , Adulto , Anciano , Niño , Preescolar , Brotes de Enfermedades , Femenino , Humanos , Lactante , Recién Nacido , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Estudios Prospectivos , EspañaRESUMEN
As part of a case-control study of community-acquired Legionnaires' disease, several factors related to residential water distribution systems and public drinking water systems were studied in the homes of 124 patients with community-acquired Legionnaire's disease and in the homes of 354 controls. The presence of water reservoirs and hot water tanks was studied in residential systems. Factors such as deficient chlorine levels, pipe repairs and other work, water flow interruptions, the use of alternative water sources, inadequate cleaning operations in public water reservoirs, and the position of the home within the public network (and whether this location constituted an endpoint) were studied in public water supply systems. Levels of legionellae in domestic water samples were also measured. Although the use of water reservoirs and hot water tanks promotes colonization by legionellae in residential systems, none of the variables studied seems to increase the incidence of community-acquired Legionnaires' disease.