Increasing Incidence of Legionellosis in the United States, 1990–2005: Changing Epidemiologic Trends

Department of Epidemiology, Emory University, Atlanta, Georgia, USA.
Clinical Infectious Diseases (Impact Factor: 8.89). 10/2008; 47(5):591-9. DOI: 10.1086/590557
Source: PubMed

ABSTRACT An abrupt increase in the incidence of legionellosis in the United States has been noted since 2003. Whether the recent increase is associated with shifting epidemiologic trends has not been well characterized.
We analyzed all cases of legionellosis reported to the Centers for Disease Control and Prevention through the National Notifiable Disease Surveillance System from 1990 through 2005.
A total of 23,076 cases of legionellosis were reported to the Centers for Disease Control and Prevention from 1990 through 2005. The number of reported cases increased by 70% from 1310 cases in 2002 to 2223 cases in 2003, with a sustained increase to >2000 cases per year from 2003 through 2005. The eastern United States showed most of the increases in age-adjusted incidence rates after 2002, with the mean rate in the Middle Atlantic states during 2003-2005 exceeding that during 1990-2002 by 96%. During 2000-2005, legionellosis cases were most commonly reported in persons aged 45-64 years. Persons aged <65 years comprised 63% of total cases in 2000-2005. Age-adjusted incidence rates in males exceeded those in females for all age groups and years. Legionellosis incidence showed marked seasonality in eastern states, with most cases reported in the summer or fall.
Reported legionellosis cases have increased substantially in recent years, particularly in the eastern United States and among middle-aged adults. Legionella infection should be considered in the differential diagnosis of any patient with pneumonia. Public health professionals should focus increased attention on detection and prevention of this important and increasing public health problem.

1 Follower
7 Reads
  • Source
    • "Some seasonality has been noted for Legionella spp. presence in water, especially in the warmer summer months with many more cases of Legionnaires' disease occurring in summer and fall than winter or spring [24] [35]. However, this baseline seasonal change appears to have been minor, as the relative abundance of Legionella spp. was only able to increase in July when this change was compounded by a dysfunction in the monochloramine generation system (see below). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Opportunistic pathogens, including Legionella spp. and non-tuberculous mycobacteria, can thrive in building hot water systems despite municipal and traditional on-site chlorine disinfection. Monochloramine is a relatively new approach to on-site disinfection, but the microbiological impact of on-site chloramine use has not been well studied. We hypothesized that comparison of the microbial ecology associated with monochloramine treatment versus no on-site treatment would yield highly dissimilar bacterial communities. Hot water samples were collected monthly from 7 locations for three months from two buildings in a Pennsylvania hospital complex supplied with common municipal water: (1) a hospital administrative building (no on-site treatment) and (2) an adjacent acute-care hospital treated on-site with monochloramine to control Legionella spp. Water samples were subjected to DNA extraction, rRNA PCR, and 454 pyrosequencing. Stark differences in the microbiome of the chloraminated water and the control were observed. Bacteria in the treated samples were primarily Sphingomonadales and Limnohabitans, whereas Flexibacter and Planctomycetaceae predominated in untreated control samples. Serendipitously, one sampling month coincided with dysfunction of the on-site disinfection system that resulted in a Legionella bloom detected by sequencing and culture. This study also demonstrates the potential utility of high-throughput DNA sequencing to monitor microbial ecology in water systems. Copyright © 2015 Elsevier GmbH. All rights reserved.
    Systematic and Applied Microbiology 03/2015; 38(3). DOI:10.1016/j.syapm.2015.02.006 · 3.28 Impact Factor
  • Source
    • "Legionnaires' disease accounts for about 1e5% of communityacquired pneumonia with perhaps 8000 to 18,000 cases occurring annually in the United States, and reported cases continue to increase each year following a substantial increase in 2003 (Marston et al., 1997; Centers for Disease Control and Prevention (CDC) & Adams DA (Coord.), 2012; Neil and Berkelman, 2008). It is indicated that legionellosis is greatly underdiagnosed and underreported and the number of cases is likely greater than reported (Bohte et al., 1995; Marston et al., 1994). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Outbreaks of Legionnaires' disease require environmental testing of water samples from potentially implicated building water systems to identify the source of exposure. A previous study reports a large impact on Legionella sample results due to shipping and delays in sample processing. Specifically, this same study, without accounting for measurement error, reports more than half of shipped samples tested had Legionella levels that arbitrarily changed up or down by one or more logs, and the authors attribute this result to shipping time. Accordingly, we conducted a study to determine the effects of sample holding/shipping time on Legionella sample results while taking into account measurement error, which has previously not been addressed. We analyzed 159 samples, each split into 16 aliquots, of which one-half (8) were processed promptly after collection. The remaining half (8) were processed the following day to assess impact of holding/shipping time. A total of 2544 samples were analyzed including replicates. After accounting for inherent measurement error, we found that the effect of holding time on observed Legionella counts was small and should have no practical impact on interpretation of results. Holding samples increased the root mean squared error by only about 3-8%. Notably, for only one of 159 samples, did the average of the 8 replicate counts change by 1 log. Thus, our findings do not support the hypothesis of frequent, significant (≥= 1 log10 unit) Legionella colony count changes due to holding.
    Water Research 10/2014; 62. DOI:10.1016/j.watres.2014.05.025 · 5.53 Impact Factor
  • Source
    • "Increases in the burden of LD [4] may be related to the expanding population of older adults in the United States. Given the fact that a substantial number of residential facilities for the elderly exist [10,11], facility managers, healthcare providers, caregivers, and local public health officials need to be aware of the potential for outbreaks among this population at higher risk for LD and LD-related mortality. "
    [Show abstract] [Hide abstract]
    ABSTRACT: During a Legionnaires' disease (LD) outbreak, combined epidemiological and environmental investigations were conducted to identify prevention recommendations for facilities where elderly residents live independently but have an increased risk of legionellosis. Survey responses (n = 143) were used to calculate attack rates and describe transmission routes by estimating relative risk (RR) and 95% confidence intervals (95% CI). Potable water collected from five apartments of LD patients and three randomly-selected apartments of residents without LD (n = 103 samples) was cultured for Legionella. Eight confirmed LD cases occurred among 171 residents (attack rate = 4.7%); two visitors also developed LD. One case was fatal. The average age of patients was 70 years (range: 62--77). LD risk was lower among residents who reported tub bathing instead of showering (RR = 0.13, 95% CI: 0.02--1.09, P = 0.03). Two respiratory cultures were characterized as L. pneumophila serogroup 1, monoclonal antibody type Knoxville (1,2,3), sequence type 222. An indistinguishable strain was detected in 31 (74%) of 42 potable water samples. Managers of elderly-housing facilities and local public health officials should consider developing a Legionella prevention plan. When Legionella colonization of potable water is detected in these facilities, remediation is indicated to protect residents at higher risk. If LD occurs among residents, exposure reduction, heightened awareness, and clinical surveillance activities should be coordinated among stakeholders. For prompt diagnosis and effective treatment, clinicians should recognize the increased risk and atypical presentation of LD in older adults.
    BMC Infectious Diseases 06/2013; 13(1):291. DOI:10.1186/1471-2334-13-291 · 2.61 Impact Factor
Show more


7 Reads