The recent declaration of an Ebola Virus Disease (EVD) outbreak in Uganda, specifically involving the Sudan strain, has once again brought this deadly disease into the limelight. In this article, we take a closer look at EVD, its history, its hosts and carriers, ways of transmission, symptoms, diagnostic methods, and available vaccines. We will also explore previous instances of EVD outbreaks.
Understanding Ebola Virus Disease (EVD)
Formerly known as Ebola haemorrhagic fever, EVD is a severe and often fatal illness that has caused several outbreaks mostly on the African continent since it was first discovered in 1976. The name of the disease comes from the Ebola River near which the initial outbreak occurred, located in the present-day Democratic Republic of Congo.
EVD is caused by an infection with any of the six species of viruses within the Ebolavirus genus: Ebola virus, Sudan virus, Taï Forest virus, Bundibugyo virus, Reston virus, and Bombali virus. Humans and nonhuman primates like monkeys, gorillas, and chimpanzees are the most common victims of these viruses.
Ebolavirus Species and Their Natural Host
The six species of Ebolavirus have distinct geographic distributions and are associated with different levels of virulence in humans. The natural host for all these viruses, notably, is the fruit bat from the Pteropodidae family, serving as a reservoir for the virus.
Transmission of Ebola Virus
The Ebola virus can spread from animals to humans through close contact with the blood, secretions, organs or other bodily fluids of infected animals such as fruit bats, chimpanzees, gorillas, monkeys, forest antelope, or porcupines. These transmissions often occur when humans encounter ill or dead animals in the rainforest.
Once the virus has crossed over to humans, it can spread from person to person. This human-to-human transmission typically requires direct contact with blood or other body fluids of an infected person who is showing symptoms or has died from Ebola.
Signs and Symptoms of Ebola
EVD symptoms can surface anywhere from 2 to 21 days after someone comes into contact with the virus, though it most often happens within 8 to 10 days. The symptoms include fever, fatigue, muscle pain, weakness, headache, sore throat, vomiting, diarrhea, impaired kidney and liver function, and both internal and external bleeding in some cases.
Diagnosing Ebola
Given that EVD symptoms can mimic those of other infectious diseases such as malaria, typhoid fever, and meningitis, it can be difficult to diagnose. Confirmation of the Ebola virus infection involves diagnostic methods like the ELISA (antibody-capture enzyme-linked immunosorbent assay), reverse transcriptase polymerase chain reaction (RT-PCR) assay, among others.
Vaccines for Ebola
While there is currently no cure for Ebola, the Ervebo (rVSV-ZEBOV) vaccine has proven highly effective in containing the disease’s spread. However, this vaccine is only approved for protection against the Zaire strain of the virus.
Ebola Virus Outbreaks in Recent History
The most widespread and devastating Ebola outbreak occurred between 2013 and 2016, primarily affecting Guinea, Liberia, and Sierra Leone. This West African outbreak led to a significant loss of life and socio-economic disruption, with the first cases recorded in Guinea in December 2013 before spreading to neighboring Liberia and Sierra Leone.