Viral Hemorrhagic Fever (VHF)
Viral hemorrhagic fevers (VHFs) refer to a group of illnesses that are caused by several distinct families of viruses. In general, the term "viral hemorrhagic fever" is used to describe a severe multisystem syndrome, as many different organs and systems in the body are affected. Characteristically, the overall vascular system is damaged, and the body's ability to regulate itself is impaired. These symptoms are often accompanied by hemorrhage (severe bleeding), which is why this group of illnesses is called hemorrhagic fevers. Ebola and Marburg are examples of VHF and are life-threatening diseases. The Centers for Disease Control and Prevention identifies hemorrhagic fever viruses as agents that could be used as biological weapons because some are highly infectious, can be easily spread through the air, and have the potential to cause great numbers of illnesses and deaths. Most viruses causing hemorrhagic fever are zoonotic, which means they are initially transmitted to humans by animal or insect reservoir hosts. If the virus is a type that can be transmitted by person-to-person contact, the traveler can infect other people. Ebola and Marburg are examples. This type of secondary transmission of the virus can occur through direct contact with infected people or their body fluids. It can also occur indirectly, through contact with objects contaminated with infected body fluids, such as bedding used by a sick person, or contaminated syringes and needles. With the exception of yellow fever and Argentine hemorrhagic fever, for which vaccines have been developed, no vaccines exist that can protect against these diseases. Therefore, prevention efforts must concentrate on avoiding contact with host species. For those hemorrhagic fever viruses that can be transmitted from one person to another, avoiding close physical contact with infected people and their body fluids is the most important way of controlling the spread of disease.