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Ahlinder J, Eriksson KIA, Hellmér M, Salomonsson E, Granberg M, Dacklin I, Elving J, Brindefalk B. Upstream land use with microbial downstream consequences: Iron and humic substances link to Legionella spp. WATER RESEARCH 2024; 256:121579. [PMID: 38631237 DOI: 10.1016/j.watres.2024.121579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 03/28/2024] [Accepted: 04/05/2024] [Indexed: 04/19/2024]
Abstract
Intensified land use can disturb water quality, potentially increasing the abundance of bacterial pathogens, threatening public access to clean water. This threat involves both direct contamination of faecal bacteria as well as indirect factors, such as disturbed water chemistry and microbiota, which can lead to contamination. While direct contamination has been well described, the impact of indirect factors is less explored, despite the potential of severe downstream consequences on water supply. To assess direct and indirect downstream effects of buildings, farms, pastures and fields on potential water sources, we studied five Swedish lakes and their inflows. We analysed a total of 160 samples in a gradient of anthropogenic activity spanning four time points, including faecal and water-quality indicators. Through species distribution modelling, Random Forest and network analysis using 16S rRNA amplicon sequencing data, our findings highlight that land use indirectly impacts lakes via inflows. Land use impacted approximately one third of inflow microbiota taxa, in turn impacting ∼20-50 % of lake taxa. Indirect effects via inflows were also suggested by causal links between e.g. water colour and lake bacterial taxa, where this influenced the abundance of several freshwater bacteria, such as Polynucleobacter and Limnohabitans. However, it was not possible to identify direct effects on the lakes based on analysis of physiochemical- or microbial parameters. To avoid potential downstream consequences on water supply, it is thus important to consider possible indirect effects from upstream land use and inflows, even when no direct effects can be observed on lakes. Legionella (a genus containing bacterial pathogens) illustrated potential consequences, since the genus was particularly abundant in inflows and was shown to increase by the presence of pastures, fields, and farms. The approach presented here could be used to assess the suitability of lakes as alternative raw water sources or help to mitigate contaminations in important water catchments. Continued broad investigations of stressors on the microbial network can identify indirect effects, avoid enrichment of pathogens, and help secure water accessibility.
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Affiliation(s)
- Jon Ahlinder
- Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Sweden; Department of Tree Breeding, Skogforsk, Sävar, SE-91821, Sweden
| | - Karolina Ida Anna Eriksson
- Department of Ecology and Environmental Sciences, Faculty of Science and Technology, Umeå University, Sweden; Umeå Marine Sciences Centre, Umeå University, Hörnefors, 905 71, Sweden.
| | - Maria Hellmér
- Department of Biology, Science Division, Swedish Food Agency, Sweden
| | - Emelie Salomonsson
- Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Sweden
| | - Malin Granberg
- Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Sweden
| | - Ingrid Dacklin
- Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Sweden
| | - Josefine Elving
- Department of Chemistry, Environment and Feed Hygiene, Swedish Veterinary Agency, Sweden
| | - Björn Brindefalk
- Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Sweden; Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Sweden
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Pampaka D, Gómez-Barroso D, López-Perea N, Carmona R, Portero RC. Meteorological conditions and Legionnaires' disease sporadic cases-a systematic review. ENVIRONMENTAL RESEARCH 2022; 214:114080. [PMID: 35964674 DOI: 10.1016/j.envres.2022.114080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 07/29/2022] [Accepted: 08/05/2022] [Indexed: 06/15/2023]
Abstract
A number of studies suggest that meteorological conditions are related to the risk of Legionnaires' disease (LD) but the findings are not consistent. A systematic review was conducted to investigate the association of weather with sporadic LD and highlight the key meteorological conditions related to this outcome. PubMed, EMBASE, The Cochrane Library and OpenGrey were searched on 26-27 March 2020 without date, language or location restrictions. Key words included "legionellosis", "legionnaires' disease", combined with "meteorological conditions", "weather", "temperature", "humidity", "rain", "ultraviolet rays", "wind speed", etc. Studies were excluded if they did not examine the exposure of interest, the outcome of interest and their association or if they only reported LD outbreak cases. The study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and it was registered in PROSPERO (#CRD42020168869). There were 811 articles, of which 17 were included in the review. The studies investigated different meteorological variables and most of them examined the combined effect of several variables. The most commonly examined factors were precipitation and temperature, followed by relative humidity. The studies suggested that increased precipitation, temperature and relative humidity were positively associated with the incidence of LD. There was limited evidence that higher wind speed, pressure, visibility, UV radiation and longer sunshine duration were inversely linked with the occurrence of LD. A period of increased but not very high temperatures, followed by a period of increased precipitation, favour the occurrence of LD. Increased awareness of the association of temperature and precipitation and LD occurrence among clinicians and public health professionals can improve differential diagnosis for cases of sporadic community-acquired pneumonia and at the same time contribute to improving LD surveillance.
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Affiliation(s)
- Despina Pampaka
- National Centre of Epidemiology, Instituto de Salud Carlos III, Madrid, Spain; European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden.
| | - Diana Gómez-Barroso
- National Centre of Epidemiology, Instituto de Salud Carlos III, Madrid, Spain; CIBER Epidemiologia y Salud Publica, Instituto de Salud Carlos III, Madrid, Spain
| | - Noemí López-Perea
- National Centre of Epidemiology, Instituto de Salud Carlos III, Madrid, Spain; CIBER Epidemiologia y Salud Publica, Instituto de Salud Carlos III, Madrid, Spain
| | - Rocio Carmona
- National Centre of Epidemiology, Instituto de Salud Carlos III, Madrid, Spain
| | - Rosa Cano Portero
- National Centre of Epidemiology, Instituto de Salud Carlos III, Madrid, Spain; CIBER Epidemiologia y Salud Publica, Instituto de Salud Carlos III, Madrid, Spain
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Lynch VD, Shaman J. The effect of seasonal and extreme floods on hospitalizations for Legionnaires' disease in the United States, 2000-2011. BMC Infect Dis 2022; 22:550. [PMID: 35705915 PMCID: PMC9202215 DOI: 10.1186/s12879-022-07489-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 05/24/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND An increasing severity of extreme storms and more intense seasonal flooding are projected consequences of climate change in the United States. In addition to the immediate destruction caused by storm surges and catastrophic flooding, these events may also increase the risk of infectious disease transmission. We aimed to determine the association between extreme and seasonal floods and hospitalizations for Legionnaires' disease in 25 US states during 2000-2011. METHODS We used a nonparametric bootstrap approach to examine the association between Legionnaires' disease hospitalizations and extreme floods, defined by multiple hydrometeorological variables. We also assessed the effect of extreme flooding associated with named cyclonic storms on hospitalizations in a generalized linear mixed model (GLMM) framework. To quantify the effect of seasonal floods, we used multi-model inference to identify the most highly weighted flood-indicator variables and evaluated their effects on hospitalizations in a GLMM. RESULTS We found a 32% increase in monthly hospitalizations at sites that experienced cyclonic storms, compared to sites in months without storms. Hospitalizations in months with extreme precipitation were in the 89th percentile of the bootstrapped distribution of monthly hospitalizations. Soil moisture and precipitation were the most highly weighted variables identified by multi-model inference and were included in the final model. A 1-standard deviation (SD) increase in average monthly soil moisture was associated with a 49% increase in hospitalizations; in the same model, a 1-SD increase in precipitation was associated with a 26% increase in hospitalizations. CONCLUSIONS This analysis is the first to examine the effects of flooding on hospitalizations for Legionnaires' disease in the United States using a range of flood-indicator variables and flood definitions. We found evidence that extreme and seasonal flooding is associated with increased hospitalizations; further research is required to mechanistically establish whether floodwaters contaminated with Legionella bacteria drive transmission.
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Affiliation(s)
- Victoria D Lynch
- Department of Environmental Health Sciences, Columbia Mailman School of Public Health, Columbia University, 722 W. 168th St, New York, NY, 10032, USA.
| | - Jeffrey Shaman
- Department of Environmental Health Sciences, Columbia Mailman School of Public Health, Columbia University, 722 W. 168th St, New York, NY, 10032, USA
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William HM, Heslin K, Kram JJF, Toberna CP, Baumgardner DJ. Association of Natural Waterways and Legionella pneumophila Infection in Eastern Wisconsin: A Case-Control Study. J Patient Cent Res Rev 2022; 9:128-131. [PMID: 35600231 PMCID: PMC9022710 DOI: 10.17294/2330-0698.1872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023] Open
Abstract
Preliminary research has suggested possible associations between natural waterways and Legionella infection, and we previously explored these associations in eastern Wisconsin using positive L. pneumophila serogroup 1 urine antigen tests (LUAT) as diagnostic. This case-control study was a secondary analysis of home address data from patients who underwent LUAT at a single eastern Wisconsin health system from 2013 to 2017. Only zip codes within the health system's catchment area that registered ≥3 positive cases and ≥50 completed tests, as well as geographically adjacent zip codes with ≥2 positive cases and ≥50 tests, were included. A 1:3 ratio of cases to randomly selected controls was used. Home addresses were geocoded and mapped using ArcGIS software (Esri); nearest waterway and distance to home was identified. Distance to nearest waterway according to ArcGIS was verified/corrected using Google Maps incognito. Distances were analyzed using chi-squared and 2-sample t-tests. Overall, mean distance to nearest waterway did not differ between cases (2958 ± 2049 ft) and controls (2856 ± 2018 ft; P=0.701). However, in a subset of nonurban zip codes, cases were closer to nearest waterway than controls (1165 ± 905 ft vs 2113 ± 1710 ft; P=0.019). No association was found between cases and type of waterway. Further research is needed to investigate associations and differences between natural and built environmental water sources in relation to legionellosis.
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Affiliation(s)
- Hannah M. William
- Advocate Aurora Research Institute, Advocate Aurora Health, Milwaukee, WI
- Center for Urban Population Health, Milwaukee, WI
- University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - Kayla Heslin
- Advocate Aurora Research Institute, Advocate Aurora Health, Milwaukee, WI
- Center for Urban Population Health, Milwaukee, WI
- Aurora UW Medical Group, Advocate Aurora Health, Milwaukee, WI
| | - Jessica J. F. Kram
- Center for Urban Population Health, Milwaukee, WI
- Aurora UW Medical Group, Advocate Aurora Health, Milwaukee, WI
- Department of Family Medicine and Community Health, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - Caroline P. Toberna
- Advocate Aurora Research Institute, Advocate Aurora Health, Milwaukee, WI
- Center for Urban Population Health, Milwaukee, WI
- Aurora UW Medical Group, Advocate Aurora Health, Milwaukee, WI
| | - Dennis J. Baumgardner
- Center for Urban Population Health, Milwaukee, WI
- Aurora UW Medical Group, Advocate Aurora Health, Milwaukee, WI
- Department of Family Medicine and Community Health, University of Wisconsin School of Medicine and Public Health, Madison, WI
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Abstract
Legionella pneumophila (LP) widely exists in natural and artificial water environments, which facilitates LP to infect people. LP infection causes Legionnaires' disease (LD), which is an important but relatively uncommon respiratory infection. Approximately 90% of LD is caused by L. pneumophila serogroup 1 (Lp1). Meteorological conditions may affect the infectivity and virulence of Lp1, but the exact relationship between them is still unclear. In this study, we evaluated the virulence of Lp1 by screening of total 156 Lp1 strains isolated from cooling tower water in different region of China by detecting their abilities to activate NF-κB signaling pathway in vitro. In addition, we screened the distribution of some selected virulence genes in these strains. The virulence, virulence gene distribution and the meteorological factors were analyzed. We found that both the virulence and the distribution of virulence genes had a certain regional and meteorological correlation. Although loss of several virulence genes showed significant effects on the virulence of Lp1 strains, the distribution of virulence genes had very limited effects on the virulence of Lp1. IMPORTANCE LD is likely to be under-recognized in many countries. Due to the widespread existence of LP in natural and artificial water environments, and to the lack of cross-protection against different strains, LP is a potentially serious threat to human health. Therefore, effective monitoring of the virulence of LP in the water environment is very important to prevent and control the prevalence of LD. Understanding the virulence of LP can not only help us to predict the risk of possible outbreaks in advance, but can also enable more targeted clinical treatment. This study highlights the importance of understanding the epidemiology and ecology of LP isolated from public facilities in terms of public health and biology. Due to the potential for water sources to harbor and disseminate LP, and to the fact that geographical conditions influence the virulence of LP, timely and accurate LP virulence surveillance is urgently needed.
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Effects of climate changes and road exposure on the rapidly rising legionellosis incidence rates in the United States. PLoS One 2021; 16:e0250364. [PMID: 33886659 PMCID: PMC8061983 DOI: 10.1371/journal.pone.0250364] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 03/30/2021] [Indexed: 11/27/2022] Open
Abstract
Legionellosis is an infection acquired through inhalation of aerosols that are contaminated with environmental bacteria Legionella spp. The bacteria require warm temperature for proliferation in bodies of water and moist soil. The legionellosis incidence in the United States has been rising rapidly in the past two decades without a clear explanation. In the meantime, the US has recorded consecutive years of above-norm temperature since 1997 and precipitation surplus since 2008. The present study analyzed the legionellosis incidence in the US during the 20-year period of 1999 to 2018 and correlated with concurrent temperature, precipitation, solar ultraviolet B (UVB) radiation, and vehicle mileage data. The age-adjusted legionellosis incidence rates rose exponentially from 0.40/100,000 in 1999 (with 1108 cases) to 2.69/100,000 in 2018 (with 9933 cases) at a calculated annual increase of 110%. In regression analyses, the rise correlated with an increase in vehicle miles driven and with temperature and precipitation levels that have been above the 1901–2000 mean since 1997 and 2008, respectively, suggesting more road exposure to traffic-generated aerosols and promotive effects of anomalous climate. Remarkably, the regressions with cumulative anomalies of temperature and precipitation were robust (R2 ≥ 0.9145, P ≤ 4.7E-11), implying possible changes to microbial ecology in the terrestrial and aquatic environments. An interactive synergy between annual precipitation and vehicle miles was also found in multiple regressions. Meanwhile, the bactericidal UVB radiation has been decreasing, which also contributed to the rising incidence in an inverse correlation. The 2018 legionellosis incidence peak corresponded to cumulative effects of the climate anomalies, vast vehicle miles (3,240 billion miles, 15904 km per capita), record high precipitation (880.1 mm), near record low UVB radiation (7488 kJ/m2), and continued above-norm temperature (11.96°C). These effects were examined and demonstrated in California, Florida, New Jersey, Ohio, and Wisconsin, states that represent diverse incidence rates and climates. The incidence and above-norm temperature both rose most in cold Wisconsin. These results suggest that warming temperature and precipitation surplus have likely elevated the density of Legionella bacteria in the environment, and together with road exposure explain the rapidly rising incidence of legionellosis in the United States. These trends are expected to continue, warranting further research and efforts to prevent infection.
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Buse HY, Morris BJ, Gomez-Alvarez V, Szabo JG, Hall JS. Legionella Diversity and Spatiotemporal Variation in The Occurrence of Opportunistic Pathogens within a Large Building Water System. Pathogens 2020; 9:E567. [PMID: 32668779 PMCID: PMC7400177 DOI: 10.3390/pathogens9070567] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 07/06/2020] [Accepted: 07/07/2020] [Indexed: 01/22/2023] Open
Abstract
Understanding Legionella survival mechanisms within building water systems (BWSs) is challenging due to varying engineering, operational, and water quality characteristics unique to each system. This study aimed to evaluate Legionella, mycobacteria, and free-living amoebae occurrence within a BWS over 18-28 months at six locations differing in plumbing material and potable water age, quality, and usage. A total of 114 bulk water and 57 biofilm samples were analyzed. Legionella culturability fluctuated seasonally with most culture-positive samples being collected during the winter compared to the spring, summer, and fall months. Positive and negative correlations between Legionella and L. pneumophila occurrence and other physiochemical and microbial water quality parameters varied between location and sample types. Whole genome sequencing of 19 presumptive Legionella isolates, from four locations across three time points, identified nine isolates as L. pneumophila serogroup (sg) 1 sequence-type (ST) 1; three as L. pneumophila sg5 ST1950 and ST2037; six as L. feeleii; and one as Ochrobactrum. Results showed the presence of a diverse Legionella population with consistent and sporadic occurrence at four and two locations, respectively. Viewed collectively with similar studies, this information will enable a better understanding of the engineering, operational, and water quality parameters supporting Legionella growth within BWSs.
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Affiliation(s)
- Helen Y. Buse
- Homeland Security and Materials Management Division, Center for Environmental Solutions & Emergency Response (CESER), Office of Research and Development (ORD), US Environmental Protection Agency (USEPA), Cincinnati, OH 45268, USA; (J.G.S.); (J.S.H.)
| | - Brian J. Morris
- Pegasus Technical Services, Inc c/o US EPA, Cincinnati, OH 45268, USA;
| | - Vicente Gomez-Alvarez
- Water Infrastructure Division, Center for Environmental Solutions & Emergency Response (CESER), US Environmental Protection Agency (USEPA), Office of Research and Development (ORD), Cincinnati, OH 45268, USA;
| | - Jeffrey G. Szabo
- Homeland Security and Materials Management Division, Center for Environmental Solutions & Emergency Response (CESER), Office of Research and Development (ORD), US Environmental Protection Agency (USEPA), Cincinnati, OH 45268, USA; (J.G.S.); (J.S.H.)
| | - John S. Hall
- Homeland Security and Materials Management Division, Center for Environmental Solutions & Emergency Response (CESER), Office of Research and Development (ORD), US Environmental Protection Agency (USEPA), Cincinnati, OH 45268, USA; (J.G.S.); (J.S.H.)
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The association between sporadic Legionnaires' disease and weather and environmental factors, Minnesota, 2011-2018. Epidemiol Infect 2020; 148:e156. [PMID: 32594925 PMCID: PMC7378963 DOI: 10.1017/s0950268820001417] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
From 2011 through 2018, there was a notable increase in sporadic Legionnaires' disease in the state of Minnesota. Sporadic cases are those not associated with a documented outbreak. Outbreak-related cases are typically associated with a common identified contaminated water system; sporadic cases typically do not have a common source that has been identified. Because of this, it is hypothesised that weather and environmental factors can be used as predictors of sporadic Legionnaires' disease. An ecological design was used with case report surveillance data from the state of Minnesota during 2011 through 2018. Over this 8-year period, there were 374 confirmed Legionnaires' disease cases included in the analysis. Precipitation, temperature and relative humidity (RH) data were collected from weather stations across the state. A Poisson regression analysis examined the risk of Legionnaires' disease associated with precipitation, temperature, RH, land-use and age. A lagged average 14-day precipitation had the strongest association with Legionnaires' disease (RR 2.5, CI 2.1-2.9), when accounting for temperature, RH, land-use and age. Temperature, RH and land-use also had statistically significant associations to Legionnaires' disease, but with smaller risk ratios. This study adds to the body of evidence that weather and environmental factors play an important role in the risk of sporadic Legionnaires' disease. This is an area that can be used to target additional research and prevention strategies.
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Optimising the case-crossover design for use in shared exposure settings. Epidemiol Infect 2020; 148:e151. [PMID: 32364110 PMCID: PMC7374809 DOI: 10.1017/s0950268820000916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
With a case-crossover design, a case's exposure during a risk period is compared to the case's exposures at referent periods. The selection of referents for this self-controlled design is determined by the referent selection strategy (RSS). Previous research mainly focused on systematic bias associated with the RSS. We additionally focused on how RSS determines the number of referents per risk, sensitivity to overdispersion and time-varying confounding. We illustrated the consequences of different RSS using a simulation study informed by data on meteorological variables and Legionnaires’ disease. By randomising the events and exposure time series, we explored statistical power associated with time-stratified and fixed bidirectional RSS and their susceptibility to systematic bias and confounding bias. In addition, we investigated how a high number of events on the same date (e.g. outbreaks) affected coefficient estimation. As illustrated by our work, referent selection alone can be insufficient to control for a time-varying confounding bias. In contrast to systematic bias, confounding bias can be hard to detect. We studied potential solutions: varying the model parameters and link-function, outlier-removal and aggregating the input-data over smaller areas. Our simulation study offers a framework for researchers looking to detect and to avoid bias in case-crossover studies.
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Short-term associations between Legionnaires' disease incidence and meteorological variables in Belgium, 2011-2019. Epidemiol Infect 2020; 148:e150. [PMID: 32345387 PMCID: PMC7374801 DOI: 10.1017/s0950268820000886] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The number of reported cases with Legionnaires' disease (LD) is increasing in Belgium. Previous studies have investigated the associations between LD incidence and meteorological factors, but the Belgian data remained unexplored. We investigated data collected between 2011 and 2019. Daily exposure data on temperature, relative humidity, precipitation and wind speed was obtained from the Royal Meteorological Institute for 29 weather stations. Case data were collected from the national reference centre and through mandatory notification. Daily case and exposure data were aggregated by province. We conducted a time-stratified case-crossover study. The 'at risk' period was defined as 10 to 2 days prior to disease onset. The corresponding days in the other study years were selected as referents. We fitted separate conditional Poisson models for each day in the 'at risk' period and a distributed lag non-linear model (DLNM) which fitted all data in one model. LD incidence showed a yearly peak in August and September. A total of 614 cases were included. Given seasonality, a sequence of precipitation, followed by high relative humidity and low wind speed showed a statistically significant association with the number of cases 6 to 4 days later. We discussed the advantages of DLNM in this context.
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Solar and Climate Effects Explain the Wide Variation in Legionellosis Incidence Rates in the United States. Appl Environ Microbiol 2019; 85:AEM.01776-19. [PMID: 31519664 DOI: 10.1128/aem.01776-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 09/04/2019] [Indexed: 11/20/2022] Open
Abstract
Legionellosis, an infection caused by the environmental bacteria Legionella spp., has become a significant public health problem in the United States in recent years; however, among the states, the incidence rates vary widely without a clear explanation. This study examined environmental effects on the 2014-to-2016 average annual legionellosis incidence rates in the U.S. states through correlative analyses with long-term precipitation, temperature, solar UV radiation, and sunshine hours. The continental states west of ∼95°W showed low incidence rates of 0.51 to 1.20 cases per 100,000 population, which corresponded to low precipitation, below 750 mm annually. For the eastern states, where precipitation was higher, solar effects were prominent and mixed, leading to wide incidence variation. Robust regressions suggested a dividing line at 40°N: north of this line, rising temperature, mainly from solar heat, raised legionellosis incidence to a peak of 4.25/100,000 in Ohio; south of the line, intensifying sunlight in terms of high UV indices and long sunshine hours prevailed to limit incidence gradually to 0.99/100,000 in Louisiana. On or near the 40°N line were 15 eastern states that had leading legionellosis incidence rates of >2.0/100,000. These states all showed modest environmental parameters. In contrast, the frigid climate in Alaska and the strong year-round solar UV in Hawaii explained the lowest U.S. incidences, 0.14/100,000 and 0.47/100,000, respectively, in these states. The findings of solar and climate effects explain the wide variation of legionellosis incidence rates in the United States and may offer insights into the potential exposure to and prevention of infection.IMPORTANCE Legionellosis, caused by the environmental bacteria Legionella spp., has become a significant public health problem in the United States in recent years, with ∼6,000 cases annually. The present study showed, through a series of correlative analyses with long-term precipitation, temperature, solar UV radiation, and sunshine hours, that these environmental conditions strongly influence the legionellosis incidence rates across the United States in mixed and dynamic fashions. The incidence rates varied remarkably by region, with the highest in Ohio and New York and the lowest in Alaska. A precipitation threshold above 750 mm was required for elevated legionellosis activity. Regression models and dividing lines between regions were established to show the promotive effect of temperature, as well as the inhibitive effects of solar UV and sunshine hours. These findings explain the wide variation of legionellosis incidence rates in the United States. They may also offer insights into potential exposure to and prevention of infection.
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Cassell K, Gacek P, Warren JL, Raymond PA, Cartter M, Weinberger DM. Association Between Sporadic Legionellosis and River Systems in Connecticut. J Infect Dis 2019; 217:179-187. [PMID: 29211873 DOI: 10.1093/infdis/jix531] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 09/29/2017] [Indexed: 11/13/2022] Open
Abstract
Background There has been a dramatic increase in the incidence of sporadic legionnaires' disease in Connecticut since 1999, but the exact reasons for this are unknown. Therefore, there is a growing need to understand the drivers of legionnaires' disease in the community. In this study, we explored the relationship between the natural environment and the spatial and temporal distribution of legionellosis cases in Connecticut. Methods We used spatial models and time series methods to evaluate factors associated with the increase and clustering of legionellosis in Connecticut. Stream flow, proximity to rivers, and residence in regional watersheds were explored as novel predictors of disease, while controlling for testing intensity and correlates of urbanization. Results In Connecticut, legionellosis incidence exhibited a strong pattern of spatial clustering. Proximity to several rivers and residence in the corresponding watersheds were associated with increased incidence of the disease. Elevated rainfall and stream flow rate were associated with increases in incidence 2 weeks later. Conclusions We identified a novel relationship between the natural aquatic environment and the spatial distribution of sporadic cases of legionellosis. These results suggest that natural environmental reservoirs may have a greater influence on the spatial distribution of sporadic legionellosis cases than previously thought.
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Affiliation(s)
- Kelsie Cassell
- Departments of Epidemiology of Microbial Diseases, New Haven, Connecticut
| | - Paul Gacek
- Connecticut Department of Public Health, Hartford
| | - Joshua L Warren
- Departments of Biostatistics, Yale School of Public Health, New Haven, Connecticut
| | - Peter A Raymond
- Yale School of Forestry and Environmental Studies, New Haven, Connecticut
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Brunn A, Fisman DN, Sargeant JM, Greer AL. The Influence of Climate and Livestock Reservoirs on Human Cases of Giardiasis. ECOHEALTH 2019; 16:116-127. [PMID: 30350000 PMCID: PMC6430827 DOI: 10.1007/s10393-018-1385-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 10/04/2018] [Accepted: 10/09/2018] [Indexed: 05/23/2023]
Abstract
Giardia duodenalis is an intestinal parasite which causes diarrhoeal illness in people. Zoonotic subtypes found in livestock may contribute to human disease occurrence through runoff of manure into multi-use surface water. This study investigated temporal associations among selected environmental variables and G. duodenalis occurrence in livestock reservoirs on human giardiasis incidence using data collected in the Waterloo Health Region, Ontario, Canada. The study objectives were to: (1) evaluate associations between human cases and environmental variables between 1 June 2006 and 31 December 2013, and (2) evaluate associations between human cases, environmental variables and livestock reservoirs using a subset of this time series, with both analyses controlling for seasonal and long-term trends. Human disease incidence exhibited a seasonal trend but no annual trend. A Poisson multivariable regression model identified an inverse association with water level lagged by 1 month (IRR = 0.10, 95% CI 0.01, 0.85, P < 0.05). Case crossover analysis found varying associations between lagged variables including livestock reservoirs (1 week), mean air temperature (3 weeks), river water level (1 week) and flow rate (1 week), and precipitation (4 weeks). This study contributes to our understanding of epidemiologic relationships influencing human giardiasis cases in Ontario, Canada.
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Affiliation(s)
- Ariel Brunn
- Department of Population Medicine, Ontario Veterinary College, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
| | - David N Fisman
- Department of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada
| | - Jan M Sargeant
- Department of Population Medicine, Ontario Veterinary College, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
- Centre for Public Health and Zoonoses, University of Guelph, Guelph, ON, Canada
- Arrell Food Institute, University of Guelph, Guelph, ON, Canada
| | - Amy L Greer
- Department of Population Medicine, Ontario Veterinary College, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada.
- Centre for Public Health and Zoonoses, University of Guelph, Guelph, ON, Canada.
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14
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Walker JT. The influence of climate change on waterborne disease and Legionella: a review. Perspect Public Health 2019; 138:282-286. [PMID: 30156484 DOI: 10.1177/1757913918791198] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Climate change is predicted to have a major impact on people's lives with the recent extreme weather events and varying abnormal temperature profiles across the world raising concerns. The impacts of global warming are already being observed, from rising sea levels and melting snow and ice to changing weather patterns. Scientists state unequivocally that these trends cannot be explained by natural variability in climate alone. Human activities, especially the burning of fossil fuels, have warmed the earth by dramatically increasing concentrations of heat-trapping gases in the atmosphere; as these concentrations increase, the more the earth will warm. Climate change and related extreme weather events are being exacerbated sooner than has previously been considered and are already adversely affecting ecosystems and human health by increasing the burden and type of disease at a local level. Changes to the marine environment and freshwater supplies already affect significant parts of the world's population and warmer temperatures, especially in more temperate regions, may see an increased spread and transmission of diseases usually associated with warmer climes including, for example, cholera and malaria; these impacts are likely to become more severe in a greater number of countries. This review discusses the impacts of climate change including changes in infectious disease transmission, patterns of waterborne diseases and the likely consequences of climate change due to warmer water, drought, higher rainfall, rising sea levels and flooding.
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Affiliation(s)
- J T Walker
- Public Health England, Porton, Salisbury SP1 3DX, UK
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15
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Hamilton KA, Prussin AJ, Ahmed W, Haas CN. Outbreaks of Legionnaires’ Disease and Pontiac Fever 2006–2017. Curr Environ Health Rep 2018; 5:263-271. [DOI: 10.1007/s40572-018-0201-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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16
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Fisman DN. Of Time and the River: How Our Understanding of Legionellosis Has Changed Since 1976. J Infect Dis 2018; 217:171-173. [PMID: 29211906 DOI: 10.1093/infdis/jix532] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 10/11/2017] [Indexed: 11/13/2022] Open
Affiliation(s)
- David N Fisman
- Division of Epidemiology, Dalla Lana School of Public Heath, University of Toronto, Canada
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17
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Prussin AJ, Schwake DO, Marr LC. Ten Questions Concerning the Aerosolization and Transmission of Legionella in the Built Environment. BUILDING AND ENVIRONMENT 2017; 123:684-695. [PMID: 29104349 PMCID: PMC5665586 DOI: 10.1016/j.buildenv.2017.06.024] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Legionella is a genus of pathogenic Gram-negative bacteria responsible for a serious disease known as legionellosis, which is transmitted via inhalation of this pathogen in aerosol form. There are two forms of legionellosis: Legionnaires' disease, which causes pneumonia-like symptoms, and Pontiac fever, which causes influenza-like symptoms. Legionella can be aerosolized from various water sources in the built environment including showers, faucets, hot tubs/swimming pools, cooling towers, and fountains. Incidence of the disease is higher in the summertime, possibly because of increased use of cooling towers for air conditioning systems and differences in water chemistry when outdoor temperatures are higher. Although there have been decades of research related to Legionella transmission, many knowledge gaps remain. While conventional wisdom suggests that showering is an important source of exposure in buildings, existing measurements do not provide strong support for this idea. There has been limited research on the potential for Legionella transmission through heating, ventilation, and air conditioning (HVAC) systems. Epidemiological data suggest a large proportion of legionellosis cases go unreported, as most people who are infected do not seek medical attention. Additionally, controlled laboratory studies examining water-to-air transfer and source tracking are still needed. Herein, we discuss ten questions that spotlight current knowledge about Legionella transmission in the built environment, engineering controls that might prevent future disease outbreaks, and future research that is needed to advance understanding of transmission and control of legionellosis.
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Affiliation(s)
- Aaron J. Prussin
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, 24061, USA
- Corresponding Author:
| | - David Otto Schwake
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Linsey C. Marr
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, 24061, USA
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18
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Unusual Legionnaires' outbreak in cool, dry Western Canada: an investigation using genomic epidemiology. Epidemiol Infect 2016; 145:254-265. [PMID: 27760576 PMCID: PMC5197926 DOI: 10.1017/s0950268816001965] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
An outbreak of Legionnaires' disease occurred in an inner city district in Calgary, Canada. This outbreak spanned a 3-week period in November-December 2012, and a total of eight cases were identified. Four of these cases were critically ill requiring intensive care admission but there was no associated mortality. All cases tested positive for Legionella pneumophila serogroup 1 (LP1) by urinary antigen testing. Five of the eight patients were culture positive for LP1 from respiratory specimens. These isolates were further identified as Knoxville monoclonal subtype and sequence subtype ST222. Whole-genome sequencing revealed that the isolates differed by no more than a single vertically acquired single nucleotide variant, supporting a single point-source outbreak. Hypothesis-based environmental investigation and sampling was conducted; however, a definitive source was not identified. Geomapping of case movements within the affected urban sector revealed a 1·0 km common area of potential exposure, which coincided with multiple active construction sites that used water spray to minimize transient dust. This community point-source Legionnaires' disease outbreak is unique due to its ST222 subtype and occurrence in a relatively dry and cold weather setting in Western Canada. This report suggests community outbreaks of Legionella should not be overlooked as a possibility during late autumn and winter months in the Northern Hemisphere.
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19
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van Heijnsbergen E, Schalk JAC, Euser SM, Brandsema PS, den Boer JW, de Roda Husman AM. Confirmed and Potential Sources of Legionella Reviewed. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:4797-815. [PMID: 25774976 DOI: 10.1021/acs.est.5b00142] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Legionella bacteria are ubiquitous in natural matrices and man-made systems. However, it is not always clear if these reservoirs can act as source of infection resulting in cases of Legionnaires' disease. This review provides an overview of reservoirs of Legionella reported in the literature, other than drinking water distribution systems. Levels of evidence were developed to discriminate between potential and confirmed sources of Legionella. A total of 17 systems and matrices could be classified as confirmed sources of Legionella. Many other man-made systems or natural matrices were not classified as a confirmed source, since either no patients were linked to these reservoirs or the supporting evidence was weak. However, these systems or matrices could play an important role in the transmission of infectious Legionella bacteria; they might not yet be considered in source investigations, resulting in an underestimation of their importance. To optimize source investigations it is important to have knowledge about all the (potential) sources of Legionella. Further research is needed to unravel what the contribution is of each confirmed source, and possibly also potential sources, to the LD disease burden.
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Affiliation(s)
- Eri van Heijnsbergen
- †National Institute for Public Health and the Environment, A. van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands
| | - Johanna A C Schalk
- †National Institute for Public Health and the Environment, A. van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands
| | - Sjoerd M Euser
- ‡Regional Public Health Laboratory Kennemerland, Haarlem, Boerhaavelaan 26, 2035 RC Haarlem, The Netherlands
| | - Petra S Brandsema
- †National Institute for Public Health and the Environment, A. van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands
| | - Jeroen W den Boer
- ‡Regional Public Health Laboratory Kennemerland, Haarlem, Boerhaavelaan 26, 2035 RC Haarlem, The Netherlands
| | - Ana Maria de Roda Husman
- †National Institute for Public Health and the Environment, A. van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands
- §Institute for Risk Assessment Sciences, Utrecht University, Yalelaan 2, 3584 CM Utrecht, The Netherlands
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20
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Chen NT, Chen MJ, Guo CY, Chen KT, Su HJ. Precipitation increases the occurrence of sporadic legionnaires' disease in Taiwan. PLoS One 2014; 9:e114337. [PMID: 25474539 PMCID: PMC4256405 DOI: 10.1371/journal.pone.0114337] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 11/07/2014] [Indexed: 11/25/2022] Open
Abstract
Legionnaires' disease (LD) is an acute form of pneumonia, and changing weather is considered a plausible risk factor. Yet, the relationship between weather and LD has rarely been investigated, especially using long-term daily data. In this study, daily data was used to evaluate the impacts of precipitation, temperature, and relative humidity on LD occurrence in Taiwan from 1995-2011. A time-stratified 2:1 matched-period case-crossover design was used to compare each case with self-controlled data using a conditional logistic regression analysis, and odds ratios (ORs) for LD occurrence was estimated. The city, gender and age were defined as a stratum for each matched set to modify the effects. For lag day- 0 to 15, the precipitation at lag day-11 significantly affected LD occurrence (p<0.05), and a 2.5% (95% CIs = 0.3-4.7%) increased risk of LD occurrence was associated with every 5-mm increase in precipitation. In addition, stratified analyses further showed that positive associations of precipitation with LD incidence were only significant in male and elderly groups and during the warm season ORs = 1.023-1.029). However, such an effect was not completely linear. Only precipitations at 21-40 (OR = 1.643 (95% CIs = 1.074-2.513)) and 61-80 mm (OR = 2.572 (1.106-5.978)) significantly increased the risk of LD occurrence. Moreover, a negative correlation between mean temperature at an 11-day lag and LD occurrence was also found (OR = 0.975 (0.953-0.996)). No significant association between relative humidity and LD occurrence was identified (p>0.05). In conclusion, in warm, humid regions, an increase of daily precipitation is likely to be a critical weather factor triggering LD occurrence where the risk is found particularly significant at an 11-day lag. Additionally, precipitation at 21-40 and 61-80 mm might make LD occurrence more likely.
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Affiliation(s)
- Nai-Tzu Chen
- Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Mu-Jean Chen
- Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- National Environmental Health Research Center, National Health Research Institutes, Miaoli, Taiwan
| | - Chao-Yu Guo
- Institution of Public Health & Department of Public Health, College of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Kow-Tong Chen
- Department of Public Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Huey-Jen Su
- Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan
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21
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Phin N, Parry-Ford F, Harrison T, Stagg HR, Zhang N, Kumar K, Lortholary O, Zumla A, Abubakar I. Epidemiology and clinical management of Legionnaires' disease. THE LANCET. INFECTIOUS DISEASES 2014; 14:1011-21. [DOI: 10.1016/s1473-3099(14)70713-3] [Citation(s) in RCA: 255] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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22
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Hedlund C, Blomstedt Y, Schumann B. Association of climatic factors with infectious diseases in the Arctic and subarctic region--a systematic review. Glob Health Action 2014; 7:24161. [PMID: 24990685 PMCID: PMC4079933 DOI: 10.3402/gha.v7.24161] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 03/03/2014] [Accepted: 06/03/2014] [Indexed: 11/23/2022] Open
Abstract
Background The Arctic and subarctic area are likely to be highly affected by climate change, with possible impacts on human health due to effects on food security and infectious diseases. Objectives To investigate the evidence for an association between climatic factors and infectious diseases, and to identify the most climate-sensitive diseases and vulnerable populations in the Arctic and subarctic region. Methods A systematic review was conducted. A search was made in PubMed, with the last update in May 2013. Inclusion criteria included human cases of infectious disease as outcome, climate or weather factor as exposure, and Arctic or subarctic areas as study origin. Narrative reviews, case reports, and projection studies were excluded. Abstracts and selected full texts were read and evaluated by two independent readers. A data collection sheet and an adjusted version of the SIGN methodology checklist were used to assess the quality grade of each article. Results In total, 1953 abstracts were initially found, of which finally 29 articles were included. Almost half of the studies were carried out in Canada (n=14), the rest from Sweden (n=6), Finland (n=4), Norway (n=2), Russia (n=2), and Alaska, US (n=1). Articles were analyzed by disease group: food- and waterborne diseases, vector-borne diseases, airborne viral- and airborne bacterial diseases. Strong evidence was found in our review for an association between climatic factors and food- and waterborne diseases. The scientific evidence for a link between climate and specific vector- and rodent-borne diseases was weak due to that only a few diseases being addressed in more than one publication, although several articles were of very high quality. Air temperature and humidity seem to be important climatic factors to investigate further for viral- and bacterial airborne diseases, but from our results no conclusion about a causal relationship could be drawn. Conclusions More studies of high quality are needed to investigate the adverse health impacts of weather and climatic factors in the Arctic and subarctic region. No studies from Greenland or Iceland were found, and only a few from Siberia and Alaska. Disease and syndromic surveillance should be part of climate change adaptation measures in the Arctic and subarctic regions, with monitoring of extreme weather events known to pose a risk for certain infectious diseases implemented at the community level.
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Affiliation(s)
- Christina Hedlund
- Department of Public Health and Clinical Medicine, Centre for Global Health Research, Umeå University, Umeå, Sweden;
| | - Yulia Blomstedt
- Department of Public Health and Clinical Medicine, Centre for Global Health Research, Umeå University, Umeå, Sweden
| | - Barbara Schumann
- Department of Public Health and Clinical Medicine, Centre for Global Health Research, Umeå University, Umeå, Sweden
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23
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Hines SA, Chappie DJ, Lordo RA, Miller BD, Janke RJ, Lindquist HA, Fox KR, Ernst HS, Taft SC. Assessment of relative potential for Legionella species or surrogates inhalation exposure from common water uses. WATER RESEARCH 2014; 56:203-13. [PMID: 24681377 DOI: 10.1016/j.watres.2014.02.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 01/07/2014] [Accepted: 02/03/2014] [Indexed: 05/22/2023]
Abstract
The Legionella species have been identified as important waterborne pathogens in terms of disease morbidity and mortality. Microbial exposure assessment is a tool that can be utilized to assess the potential of Legionella species inhalation exposure from common water uses. The screening-level exposure assessment presented in this paper developed emission factors to model aerosolization, quantitatively assessed inhalation exposures of aerosolized Legionella species or Legionella species surrogates while evaluating two generalized levels of assumed water concentrations, and developed a relative ranking of six common in-home uses of water for potential Legionella species inhalation exposure. Considerable variability in the calculated exposure dose was identified between the six identified exposure pathways, with the doses differing by over five orders of magnitude in each of the evaluated exposure scenarios. The assessment of exposure pathways that have been epidemiologically associated with legionellosis transmission (ultrasonic and cool mist humidifiers) produced higher estimated inhalation exposure doses than pathways where epidemiological evidence of transmission has been less strong (faucet and shower) or absent (toilets and therapy pool). With consideration of the large uncertainties inherent in the exposure assessment process used, a relative ranking of exposure pathways from highest to lowest exposure doses was produced using culture-based measurement data and the assumption of constant water concentration across exposure pathways. In this ranking, the ultrasonic and cool mist humidifier exposure pathways were estimated to produce the highest exposure doses, followed by the shower and faucet exposure pathways, and then the toilet and therapy pool exposure pathways.
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Affiliation(s)
| | | | | | | | - Robert J Janke
- U.S. Environmental Protection Agency, National Homeland Security Research Center, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA
| | - H Alan Lindquist
- U.S. Environmental Protection Agency, National Homeland Security Research Center, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA
| | - Kim R Fox
- U.S. Environmental Protection Agency, National Homeland Security Research Center, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA
| | - Hiba S Ernst
- U.S. Environmental Protection Agency, National Homeland Security Research Center, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA
| | - Sarah C Taft
- U.S. Environmental Protection Agency, National Homeland Security Research Center, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA.
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24
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Sansom P, Copley VR, Naik FC, Leach S, Hall IM. A case-association cluster detection and visualisation tool with an application to Legionnaires' disease. Stat Med 2013; 32:3522-38. [PMID: 23483594 PMCID: PMC3842591 DOI: 10.1002/sim.5765] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 11/09/2012] [Accepted: 01/28/2013] [Indexed: 11/08/2022]
Abstract
Statistical methods used in spatio-temporal surveillance of disease are able to identify abnormal clusters of cases but typically do not provide a measure of the degree of association between one case and another. Such a measure would facilitate the assignment of cases to common groups and be useful in outbreak investigations of diseases that potentially share the same source. This paper presents a model-based approach, which on the basis of available location data, provides a measure of the strength of association between cases in space and time and which is used to designate and visualise the most likely groupings of cases. The method was developed as a prospective surveillance tool to signal potential outbreaks, but it may also be used to explore groupings of cases in outbreak investigations. We demonstrate the method by using a historical case series of Legionnaires' disease amongst residents of England and Wales.
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Affiliation(s)
- P Sansom
- Microbial Risk Assessment, Emergency Response Department, Health Protection Agency, Porton Down, Salisbury, Wiltshire, SP4 0JG, U.K
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25
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Conza L, Casati S, Limoni C, Gaia V. Meteorological factors and risk of community-acquired Legionnaires' disease in Switzerland: an epidemiological study. BMJ Open 2013; 3:e002428. [PMID: 23468470 PMCID: PMC3612760 DOI: 10.1136/bmjopen-2012-002428] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 01/17/2013] [Accepted: 01/31/2013] [Indexed: 11/28/2022] Open
Abstract
OBJECTIVES The aim of this study was to identify meteorological factors that could be associated with an increased risk of community-acquired Legionnaires' disease (LD) in two Swiss regions. DESIGN Retrospective epidemiological study using discriminant analysis and multivariable Poisson regression. SETTING We analysed legionellosis cases notified between January 2003 and December 2007 and we looked for a possible relationship between incidence rate and meteorological factors. PARTICIPANTS Community-acquired LD cases in two Swiss regions, the Canton Ticino and the Basle region, with climatically different conditions were investigated. PRIMARY OUTCOME MEASURES Vapour pressure, temperature, relative humidity, wind, precipitation and radiation recorded in weather stations of the two Swiss regions during the period January 2003 and December 2007. RESULTS Discriminant analysis showed that the two regions are characterised by different meteorological conditions. A multiple Poisson regression analysis identified region, temperature and vapour pressure during the month of infection as significant risk factors for legionellosis. The risk of developing LD was 129.5% (or 136.4% when considering vapour pressure instead of temperature in the model) higher in the Canton Ticino as compared to the Basle region. There was an increased relative risk of LD by 11.4% (95% CI 7.70% to 15.30%) for each 1 hPa rise of vapour pressure or by 6.7% (95% CI 4.22% to 9.22%) for 1°C increase of temperature. CONCLUSIONS In this study, higher water vapour pressure and heat were associated with a higher risk of community-acquired LD in two regions of Switzerland.
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Affiliation(s)
- Lisa Conza
- Swiss National Reference Centre for Legionella, Cantonal Institute of Microbiology, Bellinzona, Switzerland
| | - Simona Casati
- Swiss National Reference Centre for Legionella, Cantonal Institute of Microbiology, Bellinzona, Switzerland
| | - Costanzo Limoni
- Alpha5, Biometrics & Data Management, Riva San Vitale, Switzerland
| | - Valeria Gaia
- Swiss National Reference Centre for Legionella, Cantonal Institute of Microbiology, Bellinzona, Switzerland
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26
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Meteorological conditions and incidence of Legionnaires' disease in Glasgow, Scotland: application of statistical modelling. Epidemiol Infect 2012; 141:687-96. [PMID: 22687530 DOI: 10.1017/s095026881200101x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
This study investigated the relationships between Legionnaires' disease (LD) incidence and weather in Glasgow, UK, by using advanced statistical methods. Using daily meteorological data and 78 LD cases with known exact date of onset, we fitted a series of Poisson log-linear regression models with explanatory variables for air temperature, relative humidity, wind speed and year, and sine-cosine terms for within-year seasonal variation. Our initial model showed an association between LD incidence and 2-day lagged humidity (positive, P = 0·0236) and wind speed (negative, P = 0·033). However, after adjusting for year-by-year and seasonal variation in cases there were no significant associations with weather. We also used normal linear models to assess the importance of short-term, unseasonable weather values. The most significant association was between LD incidence and air temperature residual lagged by 1 day prior to onset (P = 0·0014). The contextual role of unseasonably high air temperatures is worthy of further investigation. Our methods and results have further advanced understanding of the role which weather plays in risk of LD infection.
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27
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Wang SV, Coull BA, Schwartz J, Mittleman MA, Wellenius GA. Potential for bias in case-crossover studies with shared exposures analyzed using SAS. Am J Epidemiol 2011; 174:118-24. [PMID: 21540322 DOI: 10.1093/aje/kwr038] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The case-crossover method is an efficient study design for evaluating associations between transient exposures and the onset of acute events. In one common implementation of this design, odds ratios are estimated using conditional logistic or stratified Cox proportional hazards models, with data stratified on each individual event. In environmental epidemiology, where aggregate time-series data are often used, combining strata with identical exposure histories may be computationally convenient. However, when the SAS software package (SAS Institute Inc., Cary, North Carolina) is used for analysis, users can obtain biased results if care is not taken to properly account for multiple cases observed at the same time. The authors show that fitting a stratified Cox model with the "Breslow" option for handling tied failure times (i.e., ties = Breslow) provides unbiased health-effects estimates in case-crossover studies with shared exposures. The authors' simulations showed that using conditional logistic regression-or equivalently a stratified Cox model with the "ties = discrete" option-in this setting leads to health-effect estimates which can be biased away from the null hypothesis of no association by 22%-39%, even for small simulated relative risks. All methods tested by the authors yielded unbiased results under a simulated scenario with a relative risk of 1.0. This potential bias does not arise in R (R Foundation for Statistical Computing, Vienna, Austria) or Stata (Stata Corporation, College Station, Texas).
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Affiliation(s)
- Shirley V Wang
- Center for Environmental Health and Technology, Brown University, Providence, Rhode Island, USA
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28
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Faucher SP, Shuman HA. Small Regulatory RNA and Legionella pneumophila. Front Microbiol 2011; 2:98. [PMID: 21833335 PMCID: PMC3153055 DOI: 10.3389/fmicb.2011.00098] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2011] [Accepted: 04/19/2011] [Indexed: 11/13/2022] Open
Abstract
Legionella pneumophila is a gram-negative bacterial species that is ubiquitous in almost any aqueous environment. It is the agent of Legionnaires’ disease, an acute and often under-reported form of pneumonia. In mammals, L. pneumophila replicates inside macrophages within a modified vacuole. Many protein regulators have been identified that control virulence-related properties, including RpoS, LetA/LetS, and PmrA/PmrB. In the past few years, the importance of regulation of virulence factors by small regulatory RNA (sRNAs) has been increasingly appreciated. This is also the case in L. pneumophila where three sRNAs (RsmY, RsmZ, and 6S RNA) were recently shown to be important determinants of virulence regulation and 79 actively transcribed sRNAs were identified. In this review we describe current knowledge about sRNAs and their regulatory properties and how this relates to the known regulatory systems of L. pneumophila. We also provide a model for sRNA-mediated control of gene expression that serves as a framework for understanding the regulation of virulence-related properties of L. pneumophila.
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Affiliation(s)
- Sébastien P Faucher
- Complex Traits Group, Department of Microbiology, McGill University Montreal, QC, Canada
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29
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Abstract
In this paper, we review the literature on the management of pneumonia in the developed world setting. Pneumonia is usually diagnosed on the basis of a cough, respiratory distress, a fever, and chest X-ray changes. Pneumonia affects all paediatric age groups, though the highest incidence is in the under 5s. There is a significant burden of primary and secondary care illness, although mortality is low. Inpatient admission rates for pneumonia may have increased in recent years in some regions. Pneumonia is unlikely if a child presents with solely wheeze. In routine clinical practice, a microbiological diagnosis is often not made, because current tests are insensitive. Aetiology varies with geographical location, but approximately half of cases are viral. The mainstay of management of moderate pneumonia (the commonest group presenting to secondary care) is careful assessment, and oral antibiotics, followed by early discharge when the patient shows signs of improvement. We summarise the available clinical trial data from the developed world; most of these trials are not adequately powered. Patients with moderately severe pneumonia do not require invasive investigation, but clinical judgement should be used to identify and investigate more complex cases. We discuss several pathogens that have gained importance as causal agents, including non-vaccinated strains of S. pneumoniae, Panton Valentine leucocidin S. aureus, H1N1 Influenza A and Human Bocavirus. The importance of antimicrobial resistance is considered, and we review recent data on long term effects of pneumonia in childhood. By reviewing the available literature, we demonstrate that there are clear evidence gaps, and we suggest future areas for clinical research.
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Affiliation(s)
- Andrew Prayle
- University of Nottingham, Child Health, E Floor East Block, Queens Medical Centre, Nottingham, NG7 2UH.
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Tuite AR, Kinlin LM, Kuster SP, Jamieson F, Kwong JC, McGeer A, Fisman DN. Respiratory virus infection and risk of invasive meningococcal disease in central Ontario, Canada. PLoS One 2010; 5:e15493. [PMID: 21103353 PMCID: PMC2984510 DOI: 10.1371/journal.pone.0015493] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 10/03/2010] [Indexed: 11/21/2022] Open
Abstract
Background In temperate climates, invasive meningococcal disease (IMD) incidence tends to coincide with or closely follow peak incidence of influenza virus infection; at a seasonal level, increased influenza activity frequently correlates with increased seasonal risk of IMD. Methods We evaluated 240 cases of IMD reported in central Ontario, Canada, from 2000 to 2006. Associations between environmental and virological (influenza A, influenza B and respiratory syncytial virus (RSV)) exposures and IMD incidence were evaluated using negative binomial regression models controlling for seasonal oscillation. Acute effects of weekly respiratory virus activity on IMD risk were evaluated using a matched-period case-crossover design with random directionality of control selection. Effects were estimated using conditional logistic regression. Results Multivariable negative binomial regression identified elevated IMD risk with increasing influenza A activity (per 100 case increase, incidence rate ratio = 1.18, 95% confidence interval (CI): 1.06, 1.31). In case-crossover models, increasing weekly influenza A activity was associated with an acute increase in the risk of IMD (per 100 case increase, odds ratio (OR) = 2.03, 95% CI: 1.28 to 3.23). Increasing weekly RSV activity was associated with increased risk of IMD after adjusting for RSV activity in the previous 3 weeks (per 100 case increase, OR = 4.31, 95% CI: 1.14, 16.32). No change in disease risk was seen with increasing influenza B activity. Conclusions We have identified an acute effect of influenza A and RSV activity on IMD risk. If confirmed, these finding suggest that influenza vaccination may have the indirect benefit of reducing IMD risk.
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Affiliation(s)
- Ashleigh R. Tuite
- Dalla Lana School of Public Health, University of Toronto, Toronto, Canada
| | | | - Stefan P. Kuster
- Mount Sinai Hospital, Toronto, Canada
- Department of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada
| | - Frances Jamieson
- The Ontario Agency for Health Protection and Promotion, Toronto, Canada
| | - Jeffrey C. Kwong
- Dalla Lana School of Public Health, University of Toronto, Toronto, Canada
- The Ontario Agency for Health Protection and Promotion, Toronto, Canada
- Department of Family and Community Medicine, University of Toronto, Toronto, Canada
- Institute for Clinical Evaluative Sciences, Toronto, Canada
| | - Allison McGeer
- Dalla Lana School of Public Health, University of Toronto, Toronto, Canada
- Mount Sinai Hospital, Toronto, Canada
| | - David N. Fisman
- Dalla Lana School of Public Health, University of Toronto, Toronto, Canada
- Department of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada
- * E-mail:
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Amemura-Maekawa J, Kura F, Helbig JH, Chang B, Kaneko A, Watanabe Y, Isobe J, Nukina M, Nakajima H, Kawano K, Tada Y, Watanabe H. Characterization of Legionella pneumophila isolates from patients in Japan according to serogroups, monoclonal antibody subgroups and sequence types. J Med Microbiol 2010; 59:653-659. [DOI: 10.1099/jmm.0.017509-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
We collected 86 unrelated clinical Legionella pneumophila strains that were isolated in Japan during the period 1980–2008. Most (80.2 %) belonged to serogroup 1, followed by serogroups 5, 3 and 2. Interestingly, the patients with L. pneumophila serogroup 1 had a significantly higher male-to-female ratio (12.4) than the patients with other L. pneumophila serogroups (2.0) (OR, 10.5; 95 % CI, 2.5–44.5). When the serogroup 1 strains were analysed by monoclonal antibody (mAb) typing, the most prevalent subgroup was Benidorm (34.9 % of all isolates). Moreover, 79.7 % of the serogroup 1 isolates were bound by mAb 3/1, which recognizes the virulence-associated epitope. When all 86 isolates were subjected to sequence-based typing (SBT) using seven loci, they could be divided into 53 sequence types (STs). The ST with the most isolates (seven) was ST1, to which most isolates from patients and environments around the world belong. However, six of the seven ST1 isolates were isolated before 1994. Other major STs were ST306 (n=6), ST120 (n=5) and ST138 (n=5). All ST306 and ST138 isolates, except for one isolate (ST306), were suspected or confirmed to be derived from bath water, which suggests that these strains prefer bath habitats. The sources of all ST1 and ST120 isolates remain unclear. By combining the SBT and mAb data, the 86 isolates could be divided into 59 types (discrimination index, 0.984). This confirms the usefulness of this combination in epidemiological studies.
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Affiliation(s)
- Junko Amemura-Maekawa
- Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Fumiaki Kura
- Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Jürgen H. Helbig
- Institute of Medical Microbiology and Hygiene, TU Dresden, Dresden, Germany
| | - Bin Chang
- Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Akiko Kaneko
- Yamagata Prefectural Institute of Public Health, Yamagata, Japan
| | - Yuko Watanabe
- Kanagawa Prefectural Institute of Public Health, Kanagawa, Japan
| | | | | | - Hiroshi Nakajima
- Okayama Prefectural Institute for Environmental Science and Public Health, Okayama, Japan
| | - Kimiko Kawano
- Miyazaki Prefectural Institute for Public Health and Environment, Miyazaki, Japan
| | - Yuki Tada
- Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Haruo Watanabe
- Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan
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Ng V, Tang P, Jamieson F, Guyard C, Low DE, Fisman DN. Laboratory-based evaluation of legionellosis epidemiology in Ontario, Canada, 1978 to 2006. BMC Infect Dis 2009; 9:68. [PMID: 19460152 PMCID: PMC2695468 DOI: 10.1186/1471-2334-9-68] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Accepted: 05/21/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Legionellosis is a common cause of severe community acquired pneumonia and respiratory disease outbreaks. The Ontario Public Health Laboratory (OPHL) has conducted most testing for Legionella species in the Canadian province of Ontario since 1978, and represents a multi-decade repository of population-based data on legionellosis epidemiology. We sought to provide a laboratory-based review of the epidemiology of legionellosis in Ontario over the past 3 decades, with a focus on changing rates of disease and species associated with legionellosis during that time period. METHODS We analyzed cases that were submitted and tested positive for legionellosis from 1978 to 2006 using Poisson regression models incorporating temporal, spatial, and demographic covariates. Predictors of infection with culture-confirmed L. pneumophila serogroup 1 (LP1) were evaluated with logistic regression models. RESULTS 1,401 cases of legionellosis tested positive from 1978 to 2006. As in other studies, we found a late summer to early autumn seasonality in disease occurrence with disease risk increasing with age and in males. In contrast to other studies, we found a decreasing trend in cases in the recent decade (IRR 0.93, 95% CI 0.91 to 0.95, P-value = 0.001); only 66% of culture-confirmed isolates were found to be LP1. CONCLUSION Despite similarities with disease epidemiology in other regions, legionellosis appears to have declined in the past decade in Ontario, in contrast to trends observed in the United States and parts of Europe. Furthermore, a different range of Legionella species is responsible for illness, suggesting a distinctive legionellosis epidemiology in this North American region.
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Affiliation(s)
- Victoria Ng
- Child Health Evaluative Sciences, Research Institute of the Hospital for Sick Children, Toronto, Canada
- National Centre for Epidemiology and Population Health, The Australian National University, Canberra, Australia
| | - Patrick Tang
- Ontario Agency for Health Protection and Promotion, Toronto, Canada
| | - Frances Jamieson
- Ontario Agency for Health Protection and Promotion, Toronto, Canada
- Department of Pathobiology and Laboratory Medicine, University of Toronto, Toronto, Canada
| | - Cyril Guyard
- Ontario Agency for Health Protection and Promotion, Toronto, Canada
- Department of Pathobiology and Laboratory Medicine, University of Toronto, Toronto, Canada
| | - Donald E Low
- Ontario Agency for Health Protection and Promotion, Toronto, Canada
- Department of Pathobiology and Laboratory Medicine, University of Toronto, Toronto, Canada
- Department of Microbiology, Mount Sinai Hospital, Toronto, Canada
| | - David N Fisman
- Child Health Evaluative Sciences, Research Institute of the Hospital for Sick Children, Toronto, Canada
- Ontario Agency for Health Protection and Promotion, Toronto, Canada
- Department of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, Canada
- Department of Health Policy, Management, and Evaluation, University of Toronto, Toronto, Canada
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