A newly recognized agent, named Uruma virus, was isolated from the blood of 2 febrile Okinawan colonists living in the rain forest of eastern Bolivia in March 1955. Studies of its physical properties, host range and immunological characteristics have been described.
The virus was consistently pathogenic to infant mice, embryonated eggs and several tissue cell lines, but only weakly pathogenic for weanling mice, adult guinea pigs, hamsters and rabbits. Its particle size was estimated, by filtration and ultracentrifugation, to be about 25 mµ. It was found to belong to Casals' Group A, to bear a close antigenic relationship to Mayaro virus and to be more distantly related to Semliki Forest and Sindbis viruses.
Antibody studies indicated that: (a) Uruma virus was the cause of illness in the patient from whom it was isolated, and (b) infection with the virus, or a close antigenic relative, is fairly common among indigenous residents of the rain forest adjacent to Santa Cruz, Bolivia.
Present address: Head, Department of Virology, U.S. Naval Medical Research Unit #3, % American Embassy, Cairo, Egypt, U.A.R.
Present address: National Institute of Neurological Diseases and Blindness, National Institutes of Health, Bethesda, Maryland.