La Fièvre Hémorragique Ebola

One of the worst outbreaks of Ebola Hemorrhagic Fever (Ebola HF), a severe and often fatal disease in humans and other primates, is occurring in Guinea, Sierra Leone, and Liberia. Between the three, 338 fatal cases have occurred, with several more laboratory confirmation and reports in other districts.

Ebola Hemorrhagic Fever Distribution Map
Image Courtesy of CDC

Colorized Transmission Electron Micrograph
of Ebola Virus virion
Image courtesy of CDC

Ebola HF is a virus within the family Filoviridae, genus Ebolavirus. There are five subspecies of the Ebolavirus family, four of which cause disease in humans: Ebola virus (Zaire ebolavirus), Sudan virus (Sudan ebolavirus), Taï Forest Virus (Taï Forest ebolavirus, formerly, Côte d'Ivoire ebolavirus), and the Bundibugyo virus (Bundibugyo ebolavirus).

First discovered in the Democratic Republic of the Congo near the Ebola River in 1976, outbreaks have been sporadically occurring in endemic regions. The natural reservoir, or host, of ebolaviruses is still unknown, although native bats are strongly suspected due to the nature of similar viruses. Besides from the animal host, the virus can be transmitted between people by direct contact with the blood or secretions (i.e. urine, feces, saliva) of an infected person or exposure to contaminated objects. Those most often infected are families and friends that come in close contact while caring for the ill, or those in health care settings where appropriate protective equipment (masks, gloves, gowns, etc.) aren't worn and proper cleaning and disposal of medical instruments isn't performed.

Life Cycle of the Ebolavirus
Image courtesy of CDC

Symptoms of the virus may appear 2 to 21 days after exposure, although 8 to10 days is most common. Symptoms of those infected include fever, headache, joint and muscle aches, weakness, diarrhea, vomiting, stomach pain, and lack of appetite. Some may experience a rash, red eyes, hiccups, cough, sore throat, chest pain, difficulty breathing and swallowing, and bleeding inside and outside the body. The reasons behind why some get sick and are able to recover while others are not is not fully understood, although fatalities are usually in those who haven't developed a significant immune response to the virus at the time of death. Diagnosis of this disease is difficult because early symptoms of red eyes, skin rash, fever, and headache also occur in more common diseases, and treatment is supportive (balancing patients' fluids and electrolytes, maintaining oxygen status and blood pressure, and treating for any other complicating infections).

Ebola HF is unlikely to spread to nations outside of the African continent. The only reported instance of Ebola transmission in the US was Ebola-Reston virus (the fifth subspecies that doesn't cause disease in humans) from imported research monkeys in 1990, and it didn't result in clinically apparent disease.