Mycoplasma pneumoniae Circulating in Indiana

Indiana Epidemiology Newsletter
November 2006

Shawn Richards, BS
Respiratory Epidemiologist

Each year, an estimated 2 million cases and 100,000 pneumonia-related hospitalizations occur in the United States due to infection from Mycoplasma pneumoniae (1). This infection is not reportable under the Communicable Disease Reporting Rule for Physicians, Hospitals, and Laboratories, 410 IAC 1-2.3. (The Rule is available at However, under the same rule, an unusual occurrence of any disease is to be reported to the health department immediately. (See related article in the Outbreak Spotlight feature of this issue.)

Recently, astute school nurses and public health nurses reported a large respiratory outbreak in central Indiana. At least 50 cases of chest x-ray confirmed pneumonia have been identified among residents, mainly school children, from Boone, Hamilton, and Marion Counties since August 2006. At least 50 additional cases of pneumonia were diagnosed by a physician. Several cases reported contact with someone else who was ill, or from other ill students having a similar illness, prior to developing symptoms, suggesting person-to-person transmission. The Indiana State Department of Health (ISDH), in collaboration with the Boone, Hamilton, and Marion County Health Departments, actively investigated these cases and continues surveillance to identify additional cases. Symptoms have included fever (median: 102.3°F), headache, cough, fatigue, and pneumonia.

Two cases were confirmed positive for Mycoplasma pneumoniae by polymerase chain reaction testing at the ISDH Laboratory. Most cases have had no laboratory testing conducted to identify an agent of illness. M. pneumoniae is an uncommon cause of pneumonia in children younger than 5 years of age but is the leading cause of pneumonia in school-aged children. The last documented outbreak of M. pneumoniae in Indiana was in 2001, which is consistent with the finding that community-wide epidemics occur every 4-7 years. The incubation period is 2-3 weeks (range, 1-4 weeks). The reported duration of illness for cases of this outbreak has been 2½ weeks. The ISDH recommends considering a diagnosis of M. pneumoniae in patients, especially school-aged children and their contacts, exhibiting the above symptoms. However, antimicrobial prophylaxis for exposed contacts is not routinely recommended.

The clinical features of Mycoplasma pneumoniae include upper respiratory tract infections with fever, cough, malaise, and headache, which is consistent with the recent outbreak. It is a frequent cause of atypical pneumonia and peaks late summer/fall, most frequently in children/young adults but also in the elderly (2). The disease is transmitted person to person by contact with infectious respiratory secretions. Radiologically confirmed pneumonia usually develops in 5-10 percent of the cases. Approximately half of the known central Indiana outbreak cases had x-ray confirmed pneumonia. Physicians and local health departments investigating this outbreak have reported that at least 50 percent of the patients did not have evidence of pneumonia upon auscultation; however, chest x-rays indicated pneumonia was present. Of the known cases, two have been hospitalized and released; no deaths have occurred. Diagnosis of acute infections is difficult, and early recognition of outbreaks continues to be a challenge (1).

Early identification and prompt initiation of control measures are key in preventing secondary cases in an outbreak. Preventive measures may include avoiding crowded living and sleeping quarters whenever possible, especially in institutions, barracks, and ships (4). If one is voluntarily or involuntarily detained in an institution, symptomatic individuals should be isolated until 48 hours after antibiotic therapy has been started. Diagnosis of an infected person should lead to an increased index of suspicion for M. pneumoniae in household members and close contacts, and therapy should be given if a contact develops compatible lower respiratory tract illness. (3).

Health care providers observing similar illness in patients, especially school-aged children, in other counties may want to consider submitting specimens for testing at the ISDH Laboratory for surveillance purposes. Health care providers and local health departments are strongly encouraged to submit specimens if a respiratory outbreak occurs in the community. Please contact Shawn Richards, Respiratory Epidemiologist, at 317.233.7740 for details on specimen submission.


  1. Centers for Disease Control and Prevention,

  2. The ABX Guide: Diagnosis & Treatment of Infectious Diseases; Bartlett, Auwaeter, and Pham, eds. 1st ed. Montvale, NJ: Thomson PDR, 2005.

  3. American Academy of Pediatrics. Mycoplasma pneumoniae Infections. In: Pickering LK, ed. Red Book: 2003 Report of the Committee on Infectious Diseases. 26th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2003: 443-445.

  4. American Public Health Association. Mycoplasmal pneumonia. In: Heymann DL, ed. Control of Communicable Diseases Manual. 18th ed. Washington, DC: American Public Health Association; 2004: 417-419.