LEGIONELLA - World Health Organization
LEGIONELLA - World Health Organization LEGIONELLA - World Health Organization
of the impact Legionnaires’ disease can have on tourism, the priority may be greater than local morbidity and mortality suggests. The chapter provides information on surveillance systems; it also gives guidance on policies and practice for outbreak management, and on institutional roles and responsibilities when an outbreak control team is convened. Chapter 10 considers regulatory aspects of controlling Legionella in water systems and preventing legionellosis. Disease notification systems provide the basis for initiating investigations, identifying sources of infection, issuing public advice and limiting the scale and recurrence of outbreaks. Notification and investigation systems can be incorporated within regulations, which generally have a number of common features. The chapter also gives guidance on designing new regulations, emphasizing the key features that need to be considered, such as managerial responsibilities; registration and notification; system assessment and design; operational monitoring and verification; documentation of management plans and record keeping; and surveillance and audit. It also covers inclusion of specific regulations to deal with responses to outbreaks. Chapter 11 covers laboratory aspects. Accurate diagnosis of Legionella is important, because timely and appropriate therapy is the key to improving patient outcomes. The chapter reviews the five methods currently used for the laboratory diagnosis of Legionella infections — isolation of the organism on culture media, paired serology, detection of antigens in urine, demonstration of the bacterium in tissue or body fluids using immunofluorescence microscopy, and detection of bacterial deoxyribonucleic acid (DNA) using the polymerase chain reaction. xx v LEGIONELLA AND THE PREVENTION OF LEGIONELLOSIS
Chapter 1 Legionellosis Britt Hornei, Santiago Ewig, Martin Exner, Igor Tartakovsky, Louise Lajoie, Friederike Dangendorf, Susanne Surman-Lee, Barry Fields In 1976, an outbreak of severe pneumonia among the participants of the American Legion Convention in Philadelphia led to the description of Legionnaires’ disease by Fraser et al. (1977). The disease was found to be caused by the bacterium Legionella pneumophila (Legionella after the legionnaires who were infected at the convention; pneumophila meaning “lungloving”), belonging to the family Legionellaceae. The generic term “legionellosis” is now used to describe these bacterial infections, which can range in severity from a mild, febrile illness (Pontiac fever) to a rapid and potentially fatal pneumonia (Legionnaires’ disease). Legionella has been retrospectively identified as the cause of outbreaks of Legionnaires’ disease since 1947 (Terranova, Cohen & Fraser, 1978; McDade, Brenner & Bozeman, 1979). Legionellosis emerged because of human alteration of the environment, since Legionella species are found in aquatic environments, and thrive in warm water and warm, damp places, such as cooling towers. Cases can be usefully grouped by the way in which they were acquired, as community acquired, domestically acquired, nosocomial (acquired in a health-care setting, or “health-care acquired”) or travel associated. This chapter describes: • the characteristics of the main types of disease caused by Legionella (Section 1.1) • the prevalence of Legionella and risk factors for disease (Section 1.2) • treatment options (Section 1.3) • the main types of organism causing legionellosis (Section 1.4) • the factors affecting the pathogenicity of the causative organisms (their ability to cause disease) and their virulence (the degree of that ability, indicated by the mortality rate from the disease, or the organisms’ ability to invade tissues) (Section 1.5). 1.1 Types of disease This section describes the characteristics of Legionnaires’ disease, Pontiac fever and extrapulmonary syndrome (caused when L. pneumophila spreads from the respiratory system to the body). LEGIONELLA AND THE PREVENTION OF LEGIONELLOSIS
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Chapter 1 Legionellosis<br />
Britt Hornei, Santiago Ewig, Martin Exner, Igor Tartakovsky, Louise Lajoie, Friederike Dangendorf,<br />
Susanne Surman-Lee, Barry Fields<br />
In 1976, an outbreak of severe pneumonia among the participants of the American Legion<br />
Convention in Philadelphia led to the description of Legionnaires’ disease by Fraser et al.<br />
(1977). The disease was found to be caused by the bacterium Legionella pneumophila (Legionella<br />
after the legionnaires who were infected at the convention; pneumophila meaning “lungloving”),<br />
belonging to the family Legionellaceae. The generic term “legionellosis” is now used<br />
to describe these bacterial infections, which can range in severity from a mild, febrile illness<br />
(Pontiac fever) to a rapid and potentially fatal pneumonia (Legionnaires’ disease). Legionella<br />
has been retrospectively identified as the cause of outbreaks of Legionnaires’ disease since<br />
1947 (Terranova, Cohen & Fraser, 1978; McDade, Brenner & Bozeman, 1979).<br />
Legionellosis emerged because of human alteration of the environment, since Legionella<br />
species are found in aquatic environments, and thrive in warm water and warm, damp places,<br />
such as cooling towers. Cases can be usefully grouped by the way in which they were acquired,<br />
as community acquired, domestically acquired, nosocomial (acquired in a health-care setting,<br />
or “health-care acquired”) or travel associated.<br />
This chapter describes:<br />
• the characteristics of the main types of disease caused by Legionella (Section 1.1)<br />
• the prevalence of Legionella and risk factors for disease (Section 1.2)<br />
• treatment options (Section 1.3)<br />
• the main types of organism causing legionellosis (Section 1.4)<br />
• the factors affecting the pathogenicity of the causative organisms (their ability to cause<br />
disease) and their virulence (the degree of that ability, indicated by the mortality rate from<br />
the disease, or the organisms’ ability to invade tissues) (Section 1.5).<br />
1.1 Types of disease<br />
This section describes the characteristics of Legionnaires’ disease, Pontiac fever and extrapulmonary<br />
syndrome (caused when L. pneumophila spreads from the respiratory system to the body).<br />
<strong>LEGIONELLA</strong> AND THE PREVENTION OF LEGIONELLOSIS
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