Legionella Testing
Legionella Disease and Testing
Introduction
Legionella is a type of bacteria that can cause a severe form of pneumonia known as Legionnaires' disease, as well as a milder illness called Pontiac fever. Understanding the nature of the disease and the significance of testing is crucial for public health and safety.
Overview of Legionella Disease
1. Causative Agent: The disease is caused by the Legionella bacteria. There are over 60 species of Legionella, but the most common cause of the disease is the Legionella pneumophila species^(1^).
2. Transmission: Legionella is primarily found in fresh water environments like lakes and streams but can become a health concern when it multiplies in man-made water systems such as hot tubs, cooling towers, water tanks, and large plumbing systems. It is typically spread through the inhalation of mist or vapor from contaminated water, not through person-to-person contact^(2^).
3. Symptoms: Symptoms of Legionnaires' disease are similar to other forms of pneumonia and can include cough, shortness of breath, high fever, muscle aches, and headaches. Pontiac fever, the milder form, resembles the flu and does not lead to pneumonia^(3^).
4. Treatment: Early detection is crucial. When diagnosed promptly, Legionnaires' disease can be treated with antibiotics. However, if left untreated, it can lead to severe complications and even death^(4^).
Legionella Testing
Why is Testing Important?
Outbreaks of Legionnaires' disease can be linked back to specific water systems, and as such, regular testing can prevent outbreaks by identifying contamination early. Especially in large buildings like hospitals or hotels, where vulnerable populations may be exposed, testing is critical^(5^).
Types of Testing:
Culture Testing: This is the gold standard for Legionella detection. Water samples are taken from the suspected source and then cultured in a lab. After a few days, the lab can determine the concentration of Legionella in the sample^(6^).
Polymerase Chain Reaction (PCR) Testing: PCR testing is a molecular method that detects the DNA of the Legionella bacteria. It's faster than culture testing but might not always indicate the viability of the bacteria, meaning it could detect dead bacteria^(7^).
Serological Testing: This method tests the blood to determine if someone has been exposed to the bacteria by measuring the presence of specific antibodies. However, it's not always definitive and can sometimes lead to false positives^(8^).
Recommendations for Testing:
The Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) both recommend regular testing of water systems in large buildings, especially healthcare facilities. The frequency of testing will depend on several factors, including the size and type of the water system, and the population being served^(9^).
Prevention and Control
Effective prevention and control of Legionella involve multiple strategies:
Regular Maintenance: Regularly disinfect and clean water systems. This can prevent the growth and spread of Legionella bacteria^(10^).
Temperature Control: Legionella bacteria thrive in warm water. Keeping water temperatures outside of the 20°C to 50°C range can inhibit their growth^(11^).
Regular Testing: As mentioned, periodic testing of water systems is key to early detection and prevention of outbreaks.
Public Awareness: The general public should be made aware of the risks associated with Legionnaires' disease, especially when traveling or staying in large buildings.
Conclusion
Legionella is a significant public health concern, especially in environments with large or complex water systems. Regular testing, combined with preventive measures, can go a long way in ensuring that outbreaks are minimized or prevented altogether.
References:
^1^ Fields, B. S., Benson, R. F., & Besser, R. E. (2002). Legionella and Legionnaires' disease: 25 years of investigation. Clinical Microbiology Reviews, 15(3), 506-526.
^2^ Fraser, D. W., et al. (1977). Legionnaires' disease: description of an epidemic of pneumonia. The New England Journal of Medicine, 297(22), 1189-1197.
^3^ Marston, B. J., Lipman, H. B., & Breiman, R. F. (1994). Surveillance for Legionnaires' disease: Risk factors for morbidity and mortality. Archives of Internal Medicine, 154(21), 2417-2422.
^4^ Stout, J. E., & Yu, V. L. (1997). Legionellosis. The New England Journal of Medicine, 337(10), 682-687.
^5^ Garrison, L. E., et al. (2016). Vital signs: deficiencies in environmental control identified in outbreaks of Legionnaires’ disease—North America, 2000–2014. MMWR. Morbidity and Mortality Weekly Report, 65.
^6^ Doleans, A., et al. (2004). Clinical and environmental distributions of Legionella strains in France are different. Journal of Clinical Microbiology, 42(1), 458-460.
^7^ Murdoch, D. R. (2003). Diagnosis of Legionella infection. Clinical Infectious Diseases, 36(1), 64-69.
^8^ Helbig, J. H., et al. (2003). Pan-European study on culture-proven Legionnaires' disease: distribution of Legionella pneumophila serogroups and monoclonal subgroups. European Journal of Clinical Microbiology & Infectious Diseases, 22(10), 573-578.
^9^ WHO. (2007). Legionella and the prevention of legionellosis. World Health Organization.
^10^ Lin, Y. E., Stout, J. E., & Yu, V. L. (2011). Controlling Legionella in hospital drinking water: an evidence-based review of disinfection methods. Infection Control & Hospital Epidemiology, 32(2), 166-173.
^11^ Buse, H. Y., & Ashbolt, N. J. (2011). Differential growth of Legionella pneumophila strains within a range of amoebae at various temperatures associated with in-premise plumbing. Letters in Applied Microbiology, 53(2), 217-224.