Although 1976 marked the first discovery of Ebola by international scientists, the virus likely has a much deeper history lurking in Central Africa. By testing stored blood samples of 790 chimps and gorillas from Cameroon, Republic of Congo, and Gabon, scientists determined that primates had acquired Ebola prior to known human outbreaks in the areas where the samples were originally taken.[1] Subsequent blood samples of people living in Central Africa have shown that as much as 32.4% of the population possess Ebola antibodies (igGs), which they likely developed from exposure to fruit contaminated by bat saliva containing inactive strands of the virus.[1B] These findings have led the researchers to conclude that the virus has long circulated in the vast forests of Central Africa, infecting human and nonhuman primates.
Chimpanzee in tree, Kabale National Park, Uganda (Mark Duerksen, 2011)
Further evidence of a lengthy history of Ebola outbreaks comes from recent calculations based on the mutation rates of Ebola and Marburg viruses (unusually slow for RNA viruses) that show that the two filoviruses diverged from a single common source around 700 to 850 years ago—around the time when larger and more centralized Bantu speaking societies began to emerge in Central Africa.[2] Given this timeframe for Ebola’s emergence, it is highly improbable that isolated human cases of Ebola did not occur at least occasionally for several centuries before 1976. [Of course humans could have contracted other older forms of Filoviruses long before this timeline, and there has been speculation that ancient plagues such the one that struck Athens in 430 BCE were actually caused by Ebola-like filoviruses.[3]]
The reason why international scientists were unaware of the Ebola’s existence prior to 1976 may be in part explained by the research of Barry Hewlett, a medical anthropologist from Washington State University and a member of WHO’s Ebola response teams. Hewlett’s socio-cultural findings suggest that the people of Northern Uganda and Congo have developed effective methods for containing epidemic diseases such as Ebola. When the Acholi people realized that they were dealing with a more serious affliction (gemo instead of yat) during the 2000 Ebola outbreak in Gulu—Northern Uganda’s largest city—they implemented a protocol that prevented an even larger outbreak. This protocol included isolating victims in huts at least 100m from other homes, encouraging everyone to limit their movement, allowing only survivors of the illness (or, if not possible, an elderly person) to treat and bury the victims, and only eating meat freshly butchered from cattle. While the Acholi incorporated modern medicine into their local beliefs and treatments throughout the outbreak, the elders were adamant that the gemo protocol existed before the late nineteenth century arrival of Europeans. Their assertion has yet to be historically verified, but the specificity of the regiment and the degree to which it is enmeshed in the language and religious belief system of Acholi people suggest that they developed the emergency procedures over numerous generations in response to outbreaks of Ebola or other similar diseases.[4] Indigenous medical measures such as the Acholi’s may explain why prior to 1976 Ebola failed to erupt into outbreaks large enough to attract international attention.
[1] E. M. Leroy et al., “A Serological Survey of Ebola Virus Infection in Central African Nonhuman Primates,” Journal of Infectious Diseases, 190(2004), 1895-1899. Online: http://www.ncbi.nlm.nih.gov/pubmed/15529251
[1B] Dieudonne Nkoghe et al, “Risk Factors for Zaire ebolavirus—Specific IgG in Rural Gabonese Popultions,” The Journal of Infectious Diseases 204(2011), S768-S775.
[2] A. S. Carroll et. al., “Molecular Evolution of Viruses of the Family Filoviridae Based on 97 Whole-Genome Sequences,” Journal of Virology, 87(2013), 2608-2616. Online: http://www.ncbi.nlm.nih.gov/pubmed/23255795
[3] Constance Holden, “Ebola: An Ancient history of a “new” disease?” Science 272(1996), 5268. Online: http://search.proquest.com.ezp-prod1.hul.harvard.edu/docview/213553956/79244C745EFA4C4DPQ/2?accountid=11311
[4] Barry S. Hewlett and Bonnie L. Hewlett, Ebola, Culture and Politics: The Anthropology of an Emerging Disease, Belmont, CA: Thomson Wadsworth, 2008.
Arcade Africa 