Isolation of two new group C viruses, for which the names Madrid and Ossa are suggested, is reported. They are immunologically distinct from each other, but both are more closely related to Caraparu than to any other known group C virus. Each was obtained from the blood of a male entomological worker in a tropical rain forest in the Province of Bocas del Toro, R.P., suffering from a self-limited acute febrile illness. These are the first reported isolations of group C viruses from Central America.
University of Panama, School of Medicine, Panama, Republic of Panama.
Belém Virus Laboratory of the Instituto Evandro Chagas, Belém, Pará, Brazil. The Belém Virus Laboratory is maintained jointly by the Fundaçao Especial de Saude Pública and the Rockefeller Foundation.
Gorgas Memorial Laboratory, Panama, Republic of Panama.