The purpose is to test the safety and effectiveness of intravenous ribavirin therapy in persons with suspected and subsequently proven hantavirus infection. The hantavirus is spread through the air into the lungs when dry rodent feces are moved or disturbed. It is characterized by fever and bleeding.

Patients are randomized to receive either ribavirin or a placebo for 7 days. At the completion of therapy, patients will be seen on follow-up visits on days 14, 28, and 84.

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.