Eastern equine encephalitis virus infection and hemophagocytic lymphohistiocytosis in a 5-month-old infant.

Eastern equine encephalitis virus infection is a rare sporadic central nervous system infection transmitted by a mosquito vector. Hemophagocytic lymphohistiocytosis (HLH) is a rare life-threatening disease associated with the inability of an overactive immune system to effectively respond to infections. Many viruses are known to trigger primary, as well as secondary, HLH. We report a pediatric case of eastern equine encephalitis virus-associated HLH which caused severe neurologic injury and death.