Community Outbreak of Mycoplasma pneumoniae Infection: School-Based Cluster of Neurologic Disease Associated With Household Transmission of Respiratory Illness

N. Walter, et al. J Infect Dis. 2008;198:1365–1374. In December 2006, physicians at the only pediatric referral hospital in Rhode Island informed the Rhode Island Department of Health of 3 children with encephalitis or acute disseminated encephalomyelitis (ADEM) thought to be due to Mycoplasma pneumoniae infection diagnosed during a 2-week period from November to December. Two children, one of whom died, were second-grade classmates at school A; the third child attended middle school D in the same suburban area. When contacted, schools A and D reported high rates of pneumonia among students. In late November, an unusually high incidence of pneumonia was also independently reported by nurses at 2 additional elementary schools (B and C) located within 5 miles of schools A and D. An investigation was conducted to confirm that outbreaks were occurring at schools A to D, to determine the etiology of the outbreaks, and to characterize transmission within the school A community. Seventy-six cases of pneumonia, 3 cases of neurologic disease, and 1 case of severe dermatologic disease were identified among students at schools A to D during the 22 week outbreak period. Overall, 57 (75%) case patients had a positive M. pneumoniae Ig M assay and were classified as having M. pneumoniae pneumonia. Three students developed neurologic disease during the fourth month of the outbreak period in early December, after experiencing respiratory prodomes. Two students were considered to have M. pneumoniae-associated neurologic disease because they had positive results of M. pneumoniae IgM serologic testing and no alternative diagnosis. These 2 students were a 7-year-old student who had encephalitis at school A and a 14-year-old student at school D who had ADEM. The third student, a 7-year-old classmate of the case patient at school A died of encephalitis, but was seronegative for M. pneumoniae. No other etiology was identified. Severe M. pneumoniae-associated dermatologic disease was identified in a 7-year-old student from school A who developed Stevens-Johnson syndrome after receiving azithromycin for pneumonia and who was found to be M. pneumoniae IgM seropositive. Comment: A large community outbreak of M. pneumoniae went undetected for months, until a cluster of cases of life-threatening neurologic illness was identified. The findings of this study suggest that some apparently sporadic M. pneumoniae infections may be associated with unrecognized community outbreaks. Although this outbreak of M. pneumoniae was initially identified in schools, households were found to be an important site of disease transmission. Early detection of community outbreaks of M. pneumoniae infection is important because control measures might have the potential to limit transmission and prevent severe extrapulmonary sequelae. Because M. pneumoniae surveillance is not routinely conducted, detection of community outbreaks of M. pneumoniae infection continues to depend on astute clinicians having a high index of suspicion of M. pneumoniae infection and on reporting occurrences to local and state public health departments.