In this issue of The Journal are two papers (pages 1734 and 1735) reporting in two widely separated areas in the United States cases of human encephalitis, the causal relation of which to epidemic equine encephalomyelitis seems to have been proved. One of the outbreaks apparently was due to the western strain and the other outbreak due to the eastern strain of equine encephalomyelitis.
Isolation of eastern equine encephalomyelitis virus from the brains of children who died from encephalitis and proof that the virus thus isolated is infectious on intranasal instillation into mice are recent notable contributions to epidemiologic knowledge.1 This is apparently the first horse virus definitely implicated in a human disease.
During August and September an outbreak of the eastern type of equine encephalomyelitis occurred in southeastern Massachusetts, accompanied by several fatal cases of encephalitis among children. Fothergill and his colleagues2 reported the isolation of the