Pneumonia Outbreak Caused by Chlamydophila pneumoniae among US Air Force Academy Cadets, Colorado, USA

Kevin A. Fajardo

, Shauna C. Zorich, Jameson D. Voss, and Jeffrey W. Thervil

Author affiliations: US Air Force Academy, Colorado Springs, Colorado, USA (K.A. Fajardo); US Air Force School of Aerospace Medicine, Wright-Patterson Air Force Base, Ohio, USA (S.C. Zorich, J.D. Voss, J.W. Thervil); Oak Ridge Institute of Science and Education, Oak Ridge, Tennessee, USA (J.W. Thervil)

Abstract

During October 2013–May 2014, there were 102 cases of pneumonia diagnosed in US Air Force Academy cadets. A total of 73% of tested nasal washes contained Chlamydophila pneumoniae. This agent can be considered to be present on campus settings during outbreaks with numerous, seemingly disconnected cases of relatively mild pneumonia.

Chlamydophila pneumoniae is the most common Chlamydophila species that causes human infection (1). It responsible for up to 20% of community-acquired pneumonia cases in elderly adults (1). In recent years, C. pneumoniae has also been identified in outbreaks of pneumonia among younger age groups in a variety of close-quarters living environments, including military installations, prisons, universities, and single-family households (2–6).

We report the findings of our investigation into an outbreak of 102 cases of pneumonia at the US Air Force Academy, Colorado Springs, CO, USA. Laboratory testing identified C. pneumoniae as the likely causative pathogen.

The Study

The US Air Force Academy houses ≈4,000 cadets. The cadet population is composed of approximately equal-sized freshman, sophomore, junior, and senior classes. Members of each class year are randomly distributed to 1 of 40 cadet squadrons (numbered 1–40). Each squadron is composed of ≈100 cadets of both sexes. Approximately 80% of cadets are men. Ten squadrons are grouped together to form 1 of 4 cadet groups. All cadets receive their health care at the cadet clinic or other military installations.

In October 2013, a cluster of radiographic-confirmed cases of pneumonia was identified as part of routine medical surveillance by the preventive medicine staff at the US Air Force Academy. Nine cases of pneumonia were diagnosed in football team members in that month. In comparison, only 8 cases of pneumonia were diagnosed in the entire cadet population during the previous academic year. Although the incidence of mild upper respiratory infections was relatively high at the time of this cluster, cases of pneumonia other than in football players were not identified.

Dr. Fajardo is Chief of Preventive Medicine at the United States Air Force Academy, Colorado Springs, Colorado. His primary research interest is tropical infectious diseases.

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Suggested citation for this article: Fajardo KA, Zorich SC, Voss JD, Thervil JW. Pneumonia outbreak caused by Chlamydophila pneumoniae among US Air Force Academy cadets, Colorado, USA. Emerg Infect Dis. 2015 Jun [date cited]. http://dx.doi.org/10.3201/eid2106.141394

DOI: 10.3201/eid2106.141394