Ebola diseases (EBOD) are rare, but severe and often fatal viral diseases that affects humans and other primates. There are six species in the genus Ebolavirus, three of which (Bundibugyo, Sudan and Zaire) have previously caused large outbreaks. Ebolaviruses are transmitted to people from wild animals such as fruit bats, porcupines and non-human primates. They spread in the human population through direct contact with the blood, secretions, organs or other bodily fluids of infected people, and with surfaces and materials (e.g., bedding, clothing) contaminated with these fluids.
The first cases of Ebola diseases were detected in two concomitants outbreaks in Sudan and in Zaire (now the Democratic Republic of the Congo) in 1976. Since then there have been several outbreaks in many countries. Outbreaks have since occurred in the Democratic Republic of the Congo, Gabon, Guinea, Liberia, Republic of the Congo, Sierra Leone, Sudan and Uganda. In Africa, imported cases have also been found in Mali, Nigeria, Senegal and South Africa. The 2014–2016 outbreak in West Africa was the largest and most complex ever recorded, with widespread cases and a heavy death toll.
Ebola case fatality rates have varied from 25% to 90% in past outbreaks. However, with the currently available effective treatment, patients have a significantly higher chance of survival if they are treated early and given supportive care.
Ebola diseases symptoms can be sudden. They include fever, fatigue, muscle, pain, headache and sore throat. This is followed by vomiting, diarrhoea, rash, symptoms of impaired kidney and liver function, and in some cases internal and external bleeding (e.g., oozing from the gums, blood in the stool). Laboratory findings include low white blood cell and platelet counts and elevated liver enzymes.
It can be difficult to clinically distinguish Ebola diseases symptoms from other infectious diseases such as malaria, typhoid fever and meningitis. A range of diagnostic tests have been developed to confirm the presence of the virus.
The incubation period, that is, the time interval from infection with the virus to onset of symptoms, is from 2 to 21 days. A person infected with an Ebolavirus cannot spread the disease until they develop symptoms.
Supportive care—rehydration with oral or intravenous fluids—and treatment of specific symptoms improves survival. A range of potential treatments including blood products, immune therapies and drug therapies are currently being evaluated.
During the 2018–2020 Ebola virus disease (EVD) outbreak caused by Zaire ebolavirus in the Democratic Republic of the Congo, the first-ever multi-drug randomized control trial was conducted to evaluate the effectiveness and safety of drugs used in the treatment of EVD patients under an ethical framework developed in consultation with experts in the field and the DRC.
Two monoclonal antibodies (Inmazeb and Ebanga) were approved for the treatment of Zaire ebolavirus infection in adults and children by the US Food and Drug Administration in late 2020.
* Ebola disease situation reports are now included in The WHO Africa outbreaks and emergencies bulletin.
Building the legacy of Ebola: Survivors, health systems, and a blueprint for research and development