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The Epidemiology of sporadic, community-acquired Legionnaires' disease

Orkis, Lauren (2018) The Epidemiology of sporadic, community-acquired Legionnaires' disease. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Abstract

Legionnaires’ disease (LD) is the second most common type of bacterial pneumonia in the United States. It disproportionately affects elderly and immunocompromised individuals and can lead to disability and death. LD is caused by the waterborne bacterium Legionella which is found in many aqueous environments and amplified in man-made structures such as cooling towers and building water systems. LD transmission occurs through inhalation or aspiration of Legionella contaminated water. The majority of LD cases in the US and worldwide are community-acquired with no known association with other cases, which are referred to as sporadic cases. The environmental source is often unknown, thus hindering targeted control measures. The overall objective of this dissertation is to better define the epidemiology of sporadic, community-acquired LD in order to inform targeted public health interventions. This objective was addressed through three studies. The first was a literature review of environmental sources of sporadic, community-acquired LD. We found that residential potable water, large building water systems and car travel contribute to a substantial proportion of sporadic LD. Cooling towers may also be a significant source, but definitive linkage to sporadic cases is difficult. The second study assessed the prevalence of Legionella pneumophila bacteria in Allegheny County cooling towers. We found L. pneumophila in almost half of cooling towers tested; however, the concentration level was relatively low. Facilities were encouraged to develop a water management plan and conduct annual basin water emptying, quarterly cleaning, quarterly Legionella testing and diligent inspection of older towers. The third study is a prospective simulation of community-acquired LD spatiotemporal cluster detection is presented in chapter four to demonstrate the utility and performance of this method in Allegheny County. Larger, cooling tower-associated simulated outbreaks were detected. Health departments should consider adopting this method for improved LD outbreak detection, faster investigation initiation and potential disease prevention. Overall, the findings of these three complementary studies are of public health relevance given they inform locally-focused intervention strategies for LD prevention. LD is a costly disease and interventions should be efficiently tailored for local response. Health departments should allocate resources for locally-focused interventions to reduce LD incidence.


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Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Orkis, Laurenlmt61@pitt.edulmt61
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairHarrison, Leelharriso@edc.pitt.edu
Committee MemberMertz, Kristenkristen.mertz@alleghenycounty.us
Committee MemberBrooks, Mariambrooks@pitt.edu
Committee MemberStout, Janetjstout@specialpathogenslab.com
Date: 30 January 2018
Date Type: Publication
Defense Date: 6 December 2017
Approval Date: 30 January 2018
Submission Date: 21 November 2017
Access Restriction: 2 year -- Restrict access to University of Pittsburgh for a period of 2 years.
Number of Pages: 107
Institution: University of Pittsburgh
Schools and Programs: Graduate School of Public Health > Epidemiology
Degree: DrPH - Doctor of Public Health
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: epidemiology, legionnaires' disease, waterborne, infectious disease
Date Deposited: 30 Jan 2018 22:52
Last Modified: 30 Jan 2018 22:52
URI: http://d-scholarship.pitt.edu/id/eprint/33399

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