​​Viral hemorrhagic fevers (VHFs) are caused by several distinct families of viruses that cause illness in people. VHFs affect multiple organ systems in the body. Symptoms depend on the type of virus causing the infection but usually include:

• Fever
• Body aches
• Bleeding, whether bleeding internally or from openings in the body (such as the mouth and eyes)

Infected animals and insects are the natural source of viruses that cause VHFs, which are found in tropical areas of the world (including parts of Africa, Asia, and South America). Infected animals and insects can transmit the viruses to humans and sometimes other animals. Some VHFs can spread directly from person to person. There are vaccines and specific treatments available for certain VHFs, while for others, the main treatment is supportive care. Many VHFs can cause serious illness or death.

Two examples of serious VHFs are Ebola disease and Marburg virus disease, which are both caused by viruses in the filovirus family.​