A cluster of fulminant myocarditis cases in children, Baltimore, Maryland, 1997

Area of Science:

• Pediatric Cardiology
• Epidemiology
• Pathology

Background:

• Estimating the true incidence of pediatric myocarditis is challenging due to undetected mild cases.
• Prior to 1997, the highest reported number of pediatric myocarditis deaths in a single year was three.

Observation:

• An unusual cluster of nine pediatric cases with myocarditis or similar clinical presentation and myocardial fibrosis was identified in the greater Baltimore area between May and October 1997.
• The affected children were predominantly Black and male, with no identifiable risk factors.
• The disease presented with a fulminant course, characterized by malignant arrhythmias and high mortality.

Findings:

• Seven cases of active myocarditis and two cases with myocardial fibrosis were diagnosed.
• Six patients with active myocarditis and one with fibrosis died.
• Extensive testing, including immunohistochemistry, in situ hybridization, and PCR, failed to identify an etiologic agent.

Implications:

• This outbreak highlights an unusual aggregation of severe pediatric myocarditis cases with a high fatality rate.
• The lack of an identified cause necessitates further investigation into potential environmental or novel infectious triggers.
• Understanding such outbreaks is crucial for improving the diagnosis and management of pediatric myocarditis.