Hemorrhagic fever refers to a number of viral diseases that are local, or endemic, to much of the tropics and subtropics. In addition to the bleeding and fever for which they are named, they affect multiple organ systems and cause a wide range of symptoms. Some progress slowly, while others are characterized by a sudden onset and quickly become life threatening. Examples of hemorrhagic fever include:

• Yellow fever
• Dengue hemorrhagic fever
• Lassa fever
• South American hemorrhagic fever
• Hemorrhagic fever with renal syndrome
• Crimean Congo hemorrhagic fever
• Rift Valley fever
• Ebola hemorrhagic fever
• Marburg hemorrhagic fever

Each type of hemorrhagic fever is believed to be a zoonosis, or a disease passed from animals to humans. The vector and host animals and insects have been identified for most of the diseases and include mosquitoes, ticks and rodents (e.g., mice, rats, voles). The source or sources of the viruses responsible for Ebola and Marburg have yet to be identified.

Disease outbreaks are often associated with the first exposure of humans to new populations of host animals. This may result from exploration or new development for agriculture or mining. These diseases are often highly contagious and may quickly spread through a household, community or hospital.

The greatest risk for becoming infected with hemorrhagic fever is living or visiting an area where these tropical diseases are endemic. Using an effective insect repellent and wearing light-colored long pants and long-sleeved shirts helps reduce the chance of exposure through insect or tick bites. Rodent droppings and urine are also possible sources of hemorrhagic fever viruses and care should be exercised during any activity that could cause them to become airborne.

There is no cure for hemorrhagic fever. Instead, patients receive supportive care to maintain the body’s functions. This typically includes intravenous (into a vein) fluids and treatment of secondary infections. Severe cases may also require treatment for shock and organ failure. Other treatment options vary with the many types of hemorrhagic fever and may include antiviral medication, plasma transfusion or vitamin K supplementation. Some of the viruses may run their course with little trouble beyond symptoms. Others affect major organs and eventually are fatal.