Ebola Virus Disease (EVD) is a highly contagious infection caused by one of five virus species belonging to the Filoviridae family believed to be carried by fruit bats. The Zaïre, Sudan, Taï Forest, and Bundibugyo viruses cause illness in humans while the Reston species affects animals.
It is still unclear how the virus originated or how it lives in the natural environment, but it is believed to be a zoonosis (an animal disease that can spread to humans). Fruit bats are the suspected natural hosts that transmit the virus to other animals such as gorillas, chimpanzees, or monkeys. If a person comes into close contact with infected wildlife, they can spread the infection to other humans.
Person to person transmission occurs when coming into contact with the blood, organs, and bodily fluids of infected persons or cadavers without proper infection control gear (like masks, gloves, and gowns). Transmission can also occur when coming into direct contact with contaminated surfaces and materials such as clothing, unsterilized medical instruments, and infected blood products. So far, scientists have not been able to prove that the infection spreads among humans through air particles by sneezing or coughing.
More evidence is needed on the risks of sexual transmission, but all Ebola survivors should practice safe sex for at least 12 months. Due to confirmed cases of male-to-female sexual transmission, men should have their semen tested at least twice to confirm that the virus is no longer active in the body before having sexual intercourse. Humans are infectious as long as their blood contains the virus.
Ebola Virus Disease typically occurs in west and central Africa. Persons working in healthcare settings are at greater risk, especially if working in unhygienic conditions and adequate protective equipment is not available.
Usually symptoms appear between 2 to 21 days and include sudden fever, muscle pain, headache, sore throat, red eyes, and intense weakness. The illness progresses to vomiting, diarrhea, skin rashes, liver and kidney malfunction, as well as internal and external bleeding. Laboratory testing reveals low white blood cell and platelet counts as well as elevated liver enzymes. Treatment includes oral rehydration or intravenous fluids to offset dehydration and supportive care of symptoms. Ebola Virus Disease can be misdiagnosed with hemorrhagic illnesses such as Marburg Virus Disease or Lassa Fever, and initial symptoms can be misdiagnosed as Malaria or Typhoid Fever.
Travellers going to affected areas should refrain from visiting households or healthcare settings that have been affected by an Ebola outbreak. Those who care for patients with suspected or confirmed Ebola cases should wear protective gowns, gloves, masks, as well as a face shield.
Ebola Virus Disease images, life cycle, and distribution maps
Health risk description last reviewed: December 12, 2017
Country information last updated: September 20, 2018