What is the Mortality Rate for Legionellosis in the Pediatric Population?

Patient Presentation
A 3-year-old male came to clinic with a history of coughing and low grade fever for 2 days. He had copious rhinorrhea, coughing that was worse when he was lying down, and fever to 101° F. He slept poorly because of the coughing. His father denied any wheezing, emesis, diarrhea, or rashes. Several children in his daycare had similar symptoms. The past medical history was non-contributory. He was fully immunized including a seasonal influenza vaccine.

The pertinent physical exam showed a tired male in no respiratory distress with copious rhinorrhea. His temperature was 99.8° F., and respiratory rate of 22/minute with the rest of his vital signs being normal. HEENT revealed copious clear rhinorrhea, slightly dull tympanic membranes without fluid bilaterally, and some shoddy anterior cervical lymphadenopathy. His lungs had transmitted upper airway sounds. The rest of his examination was normal. The diagnosis of a viral upper respiratory infection was made and instructions for general support were given to the father. Afterwards the third year medical student had many questions because she had thought the transmitted lung sounds were wheezing. After describing how to distinguish between the two problems, a discussion about community-acquired pneumonia ensued with the attending physician. She asked about when to consider atypical pneumonias and how often they occurred in children. The attending discussed that Mycoplasma was one of the more common atypical pneumonias along with Chlamydia. “What about Legionella? That’s been in the news recently,” she asked.

Legionella is often a severe, atypical pneumonia caused by the Legionella pneumophilia. It is a gram-negative bacterium that naturally occurs in water and is transmitted by droplet inhalation. No person-to-person contact has been documented to date. Contaminated water supplies have been documented in cooling tanks, decorative fountains, hot tubs, and large plumbing systems. Household and car air conditioners do not transmit the organism. Risk factors in the pediatric populations for legionellosis are being immunodeficient and exposure. Neonates are at risk from hospital settings.

Clinically legionellosis includes fever, myalgia, cough and radiographic or clinical evidence of pneumonia, along with laboratory confirmation by culture, serum antibody detection or urine antigen detection. Gastrointestinal symptoms can occur in 20-40% of patients. Patient can have mild disease but often it is severe with altered mental status and respiratory failure. Interestingly, children show a faster decline of serum IgM levels than adults. Antigen testing can be difficult to perform and false positive results can occur because of cross-reactivity with other organisms. Another less common clinical presentation is Pontiac Fever which causes less severe symptoms and clinically appears like influenza.

Other common bacterial causes of atypical pneumonia include Mycoplasma pneumoniae and Chlamydia pneumonia.

A differential diagnosis of cough can be reviewed here. Causes of pneumonia and complications can be reviewed here and here. A review of Mycoplasma infections can be found here

Learning Point
A 2015 study of death rates from Legionella during 2000-2010 in the U.S. showed a relatively flat mortality rate of 0.38-0.40/100,000 population, but the absolute numbers of deaths increased from 107 to 135/year. Highest rates were in the July-October time frame. There were no deaths in the 85 year olds. Most deaths occurred in whites but age adjusted mortality was the same for whites and blacks. More deaths occurred in males (63%) and they also had higher age adjusted mortality.

Questions for Further Discussion
1. What are extrapulmonary manifestations of Legionella?
2. What other organisms commonly cause atypical pneumonia?
3. How do you distinguish between wheezing and transmitted upper airway sounds?
4. Why is it called Legionaire’s Disease or Pontiac Fever?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Legionaire’s Disease

Information prescriptions for patients can be found at MedlinePlus for these topics: Topics and Topics.

and at Pediatric Common Questions, Quick Answers for this topic: Legionaire’s Diseasec

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Center for Disease Control. Legionellosis – United States, 2000–2009.
August 19, 2011. 2011:60(32);1083-1086. Available from the Internet at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6032a3.htm(cited 8/24/15)

Pancer K. Patients’ age and the dynamics of IgM for L. pneumophila sg1. Przegl Epidemiol. 2014;68(1):21-6, 113-6.

Huong Ple T, Hien PT, Lan NT, Binh TQ, Tuan DM, Anh DD. First report on prevalence and risk factors of severe atypical pneumonia in Vietnamese children aged 1-15 years. BMC Public Health. 2014 Dec 18;14:1304.

Wickramasekaran RN, Sorvillo F, Kuo T. Legionnaires’ disease and associated comorbid conditions as causes of death in the U.S., 2000-2010. Public Health Rep. 2015 May-Jun;130(3):222-9.

Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital