Ebola Hemorrhagic Fever
Ebola hemorrhagic fever is one of numerous viral hemorrhagic fevers. It is a severe, often fatal disease in humans and nonhuman primates (such as monkeys, gorillas, and chimpanzees).
Ebola Hemorrhagic Fever is caused by infection with a virus of the genus Ebolavirus. When infection occurs, symptoms usually begin abruptly.
The first Ebolavirusspecies was discovered in 1976 in what is now the Democratic Republic of the Congo near the Ebola River. Since then, outbreaks have appeared sporadically.
There are five identified subspecies of Ebolavirus. Four of the five have caused disease in humans:
- Ebola virus (Zaire ebolavirus);
- Sudan virus (Sudan ebolavirus);
- Taï Forest virus (Taï Forest ebolavirus, formerly Côte d’Ivoire ebolavirus);
- Bundibugyo virus (Bundibugyo ebolavirus).
- Reston virus (Reston ebolavirus), has caused disease in nonhuman primates, but not in humans.
The natural reservoir host of ebolaviruses remains unknown. However, on the basis of available evidence and the nature of similar viruses, researchers believe that the virus is zoonotic (animal-borne) with bats being the most likely reservoir. Four of the five subtypes occur in an animal host native to Africa.
A host of similar species is probably associated with Reston virus, which was isolated from infected cynomolgous monkeys imported to the United States and Italy from the Philippines. Several workers in the Philippines and in US holding facility outbreaks became infected with the virus, but did not become ill.
Because the natural reservoir of ebolaviruses has not yet been proven, the manner in which the virus first appears in a human at the start of an outbreak is unknown. However, researchers have hypothesized that the first patient becomes infected through contact with an infected animal.
When an infection does occur in humans, there are several ways in which the virus can be transmitted to others. These include:
- Direct contact with the blood or secretions of an infected person
- Exposure to objects that have been contaminated with infected secretions
The viruses that cause Ebola Hemorrhagic Fever are often spread through families and friends because they come in close contact with infectious secretions when caring for ill persons.
During outbreaks of Ebola Hemorrhagic Fever , the disease can spread quickly within health care settings (such as a clinic or hospital). Exposure to ebolaviruses can occur in health care settings where hospital staff are not wearing appropriate protective equipment, such as masks, gowns, and gloves.
Proper cleaning and disposal of instruments, such as needles and syringes, is also important. If instruments are not disposable, they must be sterilized before being used again. Without adequate sterilization of the instruments, virus transmission can continue and amplify an outbreak.