5 Things Pharmacists Should Know About Legionnaires Disease


The recent outbreak in Disneyland sheds light on common sources of infection and prevention strategies.

The recent Legionnaires’ disease outbreak in Disneyland sheds light on common sources of infection and prevention strategies. According to the Orange County Health Care Agency, there are 16 cases linked to Anaheim, California, and Disneyland that resulted in 14 hospitalizations and 2 deaths.1 All 16 cases were reported between September 27, 2017, and November 17, 2017, and the ages of those affected range from 52 to 94.1 Some of the cases may be linked to 2 cooling towers (air-conditioning units for large buildings) located in Disneyland, which were found to have elevated levels of Legionella bacteria. There is a continuing investigation to determine other possible outbreak sources in Anaheim.

Check out these 5 things that pharmacists should know about Legionnaires’ disease:

1. Legionnaires’ disease is a type of pneumonia that can be fatal. Legionnaires’ disease is a severe form of pneumonia that usually develops 2 to 10 days after exposure. Symptoms include cough, shortness of breath, fever, muscle pain, and headaches. Legionnaires’ disease is increasing in the United States, with more than 6,000 cases reported in 2015.2 Unfortunately, Legionnaires’ disease is underdiagnosed, as the signs and symptoms are similar to pneumonia caused by other pathogens. Both a culture of a lower respiratory specimen and a urinary antigen test should be ordered when testing individuals for Legionella.

2. Common sources of infection include water systems. Legionella bacteria can be found naturally in freshwater environments, such as lakes and streams. The bacteria can become a concern when they grow and spread in human-made water systems, such as showers and faucets, cooling towers, hot tubs, decorative fountains, hot water tanks and heaters, and large plumbing systems.

3. Legionella bacteria can be transmitted through contaminated water. Individuals can develop Legionnaires’ disease by inhaling aerosolized water droplets containing the bacteria. Rarely, it can be transmitted through aspiration of contaminated drinking water. There has been just 1 case of person-to-person transmission.3 Most illnesses occur in the summer and early fall but can happen any time of the year.

4. Antibiotic therapy is needed for treatment. Individuals at increased risk of developing Legionnaires’ disease include: individuals 50 and older; current or former smokers; patients with chronic lung disease; immunocompromised patients; cancer patients; and patients with chronic conditions, such as diabetes, kidney failure, or liver failure.2

For mild cases of Legionnaires’ disease, patients can be treated with oral antibiotics for 14 to 21 days. Antibiotic therapy options include doxycycline, tigecycline, azithromycin, and a quinolone (eg, ciprofloxacin or levofloxacin). Many patients require hospitalization with intravenous antibiotics and supportive care. Immunocompromised patients should receive fluoroquinolone therapy, as the fatality rate from Legionnaires’ disease is high in this patient population.

5. Effective water management is the best way to prevent Legionnaires’ disease. Unfortunately, there are no vaccines to prevent Legionnaires’ disease. Pharmacists can play an important role in counseling patients on prevention strategies. Educate patients about hot tubs at their homes to ensure that they are properly maintained with the right disinfectant and pH levels. High temperatures found in hot tubs make it difficult to maintain disinfectant levels needed to kill Legionella. Most outbreaks are preventable with effective water management strategies.


1. Orange County Health Care Agency. Legionnaires’ disease. ochealthinfo.com/phs/about/dcepi/epi/dip/prevention/disease_listing_a_z/legion. Accessed November 17, 2017.

2. Centers for Disease Control and Prevention. Legionella (Legionnaires’ disease and pontiac fever). cdc.gov/legionella/index.html. Updated November 8, 2017. Accessed November 17, 2017.

3. Correia AM, Ferreira JS, Borges V, et al. Probable person-to-person transmission of Legionnaires’ disease. N Engl J Med. 2016;374(5):497-8. doi: 10.1056/NEJMc1505356.

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