A lung infection called Legionnaires' disease is brought on by the bacteria Legionella pneumophila. It is contracted by breathing in the bacteria from tainted water. The bacteria is naturally occurring in lakes and streams, but when it spreads and taints man-made water systems like cooling towers, showers, heaters, and fountains, it poses a health risk (Centers for Disease Control and Prevention).
Development and Multiplication of Bacteria
Once the bacteria get into contact with these water systems, they start to develop and multiply. A rapid growth is facilitated by warm temperatures. To distribute bacteria to people through inhalation, water must be aerosolized into tiny droplets.
Symptoms
Legionnaires' disease symptoms are nonspecific. They include anorexia, lethargy, and malaise (Bartram, Chartier and Lee 2). It is also categorized with a cough, shortness of breath, fever, and headaches (Centers for Disease Control and Prevention). Diarrhea and confusion may also develop (Bartram, Chartier and Lee 3). Half of the patients may develop a productive cough, while about a third may develop hemoptysis (Bartram, Chartier and Lee 3). Gastrointestinal symptoms are notable, involving nausea, diarrhea, and abdominal cramps (Bartram, Chartier and Lee 3). Disorders related to the nervous system may occur, with more than half of patients developing confusion, depression, and hallucinations (Bartram, Chartier and Lee 3).
Diagnosis
The gold standard for diagnosis of legionella disease is culturing (Rojas). Sputum culture tests are helpful in the identification of the bacteria (Schiffman), however, it is not routinely done in laboratories due to the lengthy duration and special equipment required. Hence, therefore, Legionella disease is routinely diagnosed through urine legionella antigen test such as the Binax now Legionella Urinary Antigen Test (Rojas). Blood tests are also done that will show an increase in the levels of white blood cells (Schiffman). An x-ray may be used to show how far the disease has developed, however, on its own cannot be used to diagnose the disease.
Prevention
The aim of prevention is limiting the growth and aerosolization of the bacteria (Schiffman). Disinfection, design, and maintenance of water systems are key in prevention of the disease and to reduce the growth of the bacteria (Centers for Disease Control and Prevention). Methods of disinfection include superheating, copper-silver ionization, and mono-chloramine disinfection (Schiffman). Water systems should be kept below 20 degrees or above 50 degrees to prevent the growth of the bacteria, which thrive at a temperature range of 20-45 Degrees Celsius.
Epidemiology
Poor surveillance systems have made it hard to elaborately track the occurrence of the legionella disease, however, it is thought to occur worldwide. It is common in parts of Europe, USA, and Australia whereby in a population of one million, 10-15 cases are reported. 5000 cases are reported annually in the US (Centers for Disease Control and Prevention), with an annual incidence of approximately 75000-100000 worldwide. The annual deaths due to the disease in the USA is 5 while worldwide it is approximately 10-30% of reported cases (3000 cases), however, this figure may be more due to poor surveillance in the continents of Africa and Asia (Bartram, Chartier and Lee 144). Outbreaks are common in large buildings that have complex water systems, cruise ships, hotels, and resorts (Centers for Disease Control and Prevention). The first confirmed case of Legionella disease in the US was during the 1976 outbreak in Philadelphia. There have been other outbreaks worldwide such as the 1985 outbreak at Stanford district hospital in the UK.
References
Bartram, Jamie, et al. “LEGIONELLA and the prevention of legionellosis.” World Health Organization (2007): 1-4. Web. 17 March 2017.
Centers for Disease Control and Prevention. Legionella (Legionnaires’ Disease and Pontiac Fever). 11 January 2017. Web.
Rojas, Almudena. “Value of Serological Testing for Diagnosis of Legionellosis in Outbreak Patients.” Journal of Clinical Microbiology (2004). Web.
Schiffman, George. “Legionnaires’ Disease and Pontiac Fever.” 23 March 2016. MedicineNet.com. Web. 14 March 2017.
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