A Collaborative Double-Blind Placebo-Controlled Trial of Intravenous Ribavirin As a Treatment for Presumed Hantavirus Pulmonary Syndrome

Inclusion Criteria: You may be eligible for this study if you: * Are 12 years of age or older. * Are not pregnant. * Agree to practice sexual abstinence or use accepted barrier methods of birth control/contraception. * Are not breast-feeding. * Have a positive blood test for hantavirus. * Have symptoms suggestive of hantavirus illness. Exclusion Criteria: You will not be eligible for this study if you: * Have severe low blood count (anemia). * Have a diagnosis of other respiratory viruses (influenza, RSV, etc.). * Have group A Streptococcus with symptoms of streptococcal pharyngitis, a positive culture from a normally sterile site, or symptoms of bacterial pneumonia. * Are HIV positive. * Have cancer. * Have had any period of irregular heartbeat. * Have had chemotherapy or other drugs that suppress the immune system within 30 days. * Have taken by mouth or injection any antiviral drug (other than acyclovir, famciclovir, amantadine or rimantadine.) * Have taken by mouth or injection corticosteroids equivalent to approximately 0.5 mg/kg prednisone. * Have taken any experimental drug within 30 days prior to enrollment.