Viral hemorrhagic fevers (VHFs) are diseases caused by several distinct viral families usually found in animals, especially certain rats and mice, or insects such as mosquitoes. But the origins of some viruses are not yet known.

Viral hemorrhagic fevers affect multiple organs in the body and range from mild to life-threatening. The symptoms of viral hemorrhagic fevers vary, but often include:

• Fever.
• Fatigue or exhaustion.
• Dizziness.
• Muscle aches.
• Weakness.

When the illness is severe, symptoms may include bleeding (hemorrhage) under the skin, in internal organs, or from body orifices such as the mouth, eyes, or ears. Other symptoms of severe illness include shock, coma, and seizures.

Although some treatments, such as the antiviral drug ribavirin, may help relieve some symptoms, no standard cure exists for viral hemorrhagic fevers. Also, vaccines are available for only two strains of viral hemorrhagic fevers: yellow fever and Argentine hemorrhagic fever. Avoiding contact with the animals and insects known to carry viral hemorrhagic fevers is the main form of protection.