Slow Virus Diseases: Diseases of viral origin, characterized by incubation periods of months to years, insidious onset of clinical manifestations, and protracted clinical course. Though the disease process is protracted, viral multiplication may not be unusually slow. Conventional viruses produce slow virus diseases such as SUBACUTE SCLEROSING PANENCEPHALITIS, progressive multifocal leukoencephalopathy (LEUKOENCEPHALOPATHY, PROGRESSIVE MULTIFOCAL), and AIDS. Diseases produced by unconventional agents were originally considered part of this group. They are now called PRION DISEASES.Viruses, Unclassified: Viruses whose taxonomic relationships have not been established.Pulmonary Adenomatosis, Ovine: A contagious, neoplastic, pulmonary disease of sheep characterized by hyperplasia and hypertrophy of pneumocytes and epithelial cells of the lung. It is caused by JAAGSIEKTE SHEEP RETROVIRUS.Marburg Virus Disease: An RNA virus infection of rhesus, vervet, and squirrel monkeys transmissible to man.Virus Diseases: A general term for diseases produced by viruses.Ross River virus: A species of ALPHAVIRUS associated with epidemic EXANTHEMA and polyarthritis in Australia.Hemorrhagic Fevers, Viral: A group of viral diseases of diverse etiology but having many similar clinical characteristics; increased capillary permeability, leukopenia, and thrombocytopenia are common to all. Hemorrhagic fevers are characterized by sudden onset, fever, headache, generalized myalgia, backache, conjunctivitis, and severe prostration, followed by various hemorrhagic symptoms. Hemorrhagic fever with kidney involvement is HEMORRHAGIC FEVER WITH RENAL SYNDROME.Alphavirus Infections: Virus diseases caused by members of the ALPHAVIRUS genus of the family TOGAVIRIDAE.Respiratory Syncytial Virus Infections: Pneumovirus infections caused by the RESPIRATORY SYNCYTIAL VIRUSES. Humans and cattle are most affected but infections in goats and sheep have been reported.