Legionärskrankheit in Deutschland unter besonderer Berücksichtigung der im Krankenhaus oder in einer Pflegeeinrichtung erworbenen Erkrankungen, 2004 – 2006

Differential Seasonality of Legionnaires' Disease by Exposure Category

Legionnaires’ disease (LD) shows a seasonal pattern with most cases occurring in summer. We investigate if seasonality can be observed for all three exposure categories (community-acquired (CALD), travel-associated (TALD) and healthcare-associated (HCA)). Methods: LD cases (2005–2015) were classified by exposure categories and we calculated the relative case ratio for each month from February to December using January as reference. The TALD relative case ratio was compared with flight frequencies. Results: Overall case numbers in Germany (N = 7351) peaked in August. CALD had a curve similar to all cases. TALD displayed a bimodal curve with peaks in June/July and October. The latter was attributable to LD cases aged 60+. The relative case ratio of TALD surpassed clearly that of CALD. The curve was similar to that of the relative flight frequencies, but was shifted by about one month. HCA showed no apparent seasonality. Conclusions: Although the overall seasonality in LD is heavily influenced by CALD, seasonal differences are more pronounced for TALD which may reflect travel behavior. The bimodal pattern of TALD is attributable to the curve among those aged 60+ and may reflect their preference to travel outside school holiday periods. Heightened vigilance for HCA cases is necessary throughout the entire year.

Lessons From an Outbreak of Legionnaires' Disease on a Hematology-Oncology Unit

OBJECTIVES

To define the scope of an outbreak of Legionnaires’ disease (LD), to identify the source, and to stop transmission.

DESIGN AND SETTING

Epidemiologic investigation of an LD outbreak among patients and a visitor exposed to a newly constructed hematology-oncology unit.

METHODS

An LD case was defined as radiographically confirmed pneumonia in a person with positive urinary antigen testing and/or respiratory culture for Legionella and exposure to the hematology-oncology unit after February 20, 2014. Cases were classified as definitely or probably healthcare-associated based on whether they were exposed to the unit for all or part of the incubation period (2–10 days). We conducted an environmental assessment and collected water samples for culture. Clinical and environmental isolates were compared by monoclonal antibody (MAb) and sequence-based typing.

RESULTS

Over a 12-week period, 10 cases were identified, including 6 definite and 4 probable cases. Environmental sampling revealed Legionella pneumophila serogroup 1 (Lp1) in the potable water at 9 of 10 unit sites (90%), including all patient rooms tested. The 3 clinical isolates were identical to environmental isolates from the unit (MAb2-positive, sequence type ST36). No cases occurred with exposure after the implementation of water restrictions followed by point-of-use filters.

CONCLUSIONS

Contamination of the unit’s potable water system with Lp1 strain ST36 was the likely source of this outbreak. Healthcare providers should routinely test patients who develop pneumonia at least 2 days after hospital admission for LD. A single case of LD that is definitely healthcare associated should prompt a full investigation.

[Generally accepted engineering standards and Legionella in drinking water : findings from Frankfurt am Main]

To investigate the association between the engineering standards of drinking water systems and the extent of the Legionella colonization, we subjected our 2006 published data of the drinking water monitoring of the city's public health services for Frankfurt on Main, Germany, to closer analysis. A total of 413 records were available, with both technical data and results of the Legionella colonization. When comparing the classes of technical deficiencies of the drinking water installations with the Legionella colonization results, 93% of the Legionella data "not dedectable in 100 ml" were found in the group of drinking water installations that were technically assessed as "free of deficiencies". Thus, "good" technical engineering is associated with low or lack of Legionella colonization with a high probability even with hints for a dose-effect phenomenon-the more engineering deficiencies that exist, the higher the Legionella contamination.