Occurrence of eastern encephalitis virus in house sparrows

D URING the late summer and fall of 1959 a die-off occurred among House Sparrows (Passer domesticus) in Prince George’ s County, Maryland, simultaneously with an epizootic of eastern equine encephalomyelitis (EEE) in horses on the Eastern Shore of Maryland (Bryne, et al., in press). This paper reports the results of our investigation of the sparrow die-off which may have been due to this viral disease and reports the first isolation of the EEE virus from House Sparrows collected in Maryland. During the period 195&1958 occasional reports of sick and dying House Sparrows were received at the Patuxent Wildlife Research Center, Laurel, Maryland. Some of the birds were subjected to extensive tests, but no diagnosis was made. Many of the others were received in too poor a condition for study. The reported symptoms of these birds were those characteristic of brain damage, chiefly circling or loss of coordination of movement and general malaise (personal communication from C. M. Herman, 1961). On 15 July 1959, a sick adult male House Sparrow was received from John S. Frankenfeld, Glen Moore, Pennsylvania. The bird was extremely depressed, unable to fly or to hold its head erect. The vent was soiled with greenish feces. When the bird was placed on a hard surface it would tumble over onto its left side. It was placed in a cage for further observation. The bird became comatose and finally died on 17 July. Microscopic examination of sections taken from the cerebral cortex and from the cerebellum revealed no pathological changes. No diagnosis was made. On 6 August 1959, sick and dying House Sparrows were reported from the vicinity of Laurel, Maryland. None of these sparrows was obtained for examination. During September, reports of sick or dead sparrows were received from Laurel, College Park, Oxon Hill, and the Agricultural Research Center, Beltsville, Maryland. A die-off among sparrows was reported in a rural area bordering the Patuxent Wildlife Research Center. The same general symptoms were reported. Up on investigation at the last site, three partially decomposed House Sparrows were found on a lawn. Two other carcasses, probably House Sparrows, were found beneath trees adjacent to the lawn. A neighbor reported that she had seen several sparrows behaving abnormally around her chicken yard. These sparrows exhibited incoordination, falling over when alighting, and flew with considerable difficulty. A few dead sparrows had been found. On 15 September 1959, a sick male House Sparrow was received from Mrs. Fred Maxwell, Laurel, Maryland. This bird had been observed for two