Ebolavirus is a Filovirus, a category of worm-shaped virus that causes hemorrhagic fever. It is an RNA virus, meaning it makes mutations more frequently, giving it the ability to evolve rapidly. The disease is spread when infected bodily fluids make contact with an orifice like mouth, eyes, or skin wounds, though not typically through respiratory droplets. However, many fear the possibility of airborne spread, which was observed in a strain of ebolavirus that causes severe illness in another primate species, crab-eating macaques. Though this strain does not cause disease in infected humans, it sets off alarm bells over the possibility of human ebolaviruses to mutate airborne transmission.

Ebola attacks the immune system and causes spontaneous cell death, and patients with a strong immune system that produces a lot of antibodies as a reaction have better survival. Symptoms include high fever, sore throat, fatigue, and muscle pain, which escalates into vomiting, diarrhea, rash, organ failure, and bleeding both internally and externally. Symptoms tend to arise 10-11 days after infection, but can range from 2-21. Patients are most infectious when they have the highest quantity of viral particles, meaning they are most likely to spread the disease by the end of the infection. This means the bodies of those that succumbed to the disease were extremely infectious, which ended up playing a crucial role in disease transmission. Cultural burial practices involved grieving funeral attendants making contact with the body; “at least 20% of new Ebola infections” were estimated to originate from patients’ burials.

The Filoviridae family, consisting solely of Ebola and Marburg viruses, is estimated to be many millions of years old, but has only recently become relevant to humans because of spillover events and epidemics caused by urbanization. Outbreaks are usually the result of spillover from animal hosts, and encroachment into wild areas and close proximity enable diseases to infect humans and spread rapidly throughout populations. Bats are suspected to be Ebola’s natural host, since its RNA is found in wild populations and with milder mortality rates, though no live virus has been identified. Although a live ebola has not been found in wild bats, they travel great distances and live in communities, which facilitates the spread of disease. In addition to interaction with wild areas, Filovirus spillover is also seen in humans working with animals, like in 1967, when several employees at a lab manufacturing polio vaccines using cells from African green monkeys fell sick. Seven of the 31 infected patients died and researchers studied the lab for a possible infectious agent, isolating an RNA segment they named Marburg after the city it was found in. 

Almost a decade later, a funeral was held for a man that fell ill with an unknown disease, resulting in 21 funeral goers contracting the disease. People speculated that this outbreak, with its high virulence and rapid spread, could be another instance of Marburg. However, despite their similar appearance under a microscope, the RNA viruses were different, and the new disease earned its own name: Ebola, named after a river in the Democratic Republic of Congo (formerly known as Zaire), where the outbreak occurred. As the disease continued to spread, fatality rates soared, with 88% of the 318 individuals infected with the Zaire strain dying from infection. 

Around this time, South Sudan experienced an outbreak, but of a completely different strain of ebolavirus with a lower mortality rate around 50%. Things cooled down after these outbreaks, as the disease more or less fizzled out until 1994-1996 with outbreaks of Ebola Zaire in two African countries, then in five countries with different strains from 2000-2013. These outbreaks were confined to a few hundred cases at most, not attracting too much attention until 2014. Next week’s post will start with that year, the start of the epidemic that claims credit for much of Ebola’s fame.

It has been a hot minute since I’ve done an Education in Epidemiology post, but I’ve really been enjoying all of the innovations I’ve been learning through my Synopses! Also, the podcast these posts are based on was randomly removed from YouTube Music, the streaming service I use, which I assumed would be remedied at some point, but it’s been months and nothing has changed. It’s not a huge deal, but it makes writing these a little less accessible.

Anyway, it was really interesting to learn about Ebola, and these posts are much better at helping me retain information than passively listening to episodes, which was particularly needed for this virus. Considering I was nine in 2014, I really didn’t know much about Ebola prior to listening to this episode, other than knowing it was a scary disease. The only memory I have attached to it is the time I freaked out with my friend because her mom told her she had Ebola because we didn’t know what the Cheeto dust on her leg was. 

I would have liked to hear more about the biological mechanisms of the virus and how the disease was confined in each outbreak, because it’s extremely impressive that some events were limited to just a few dozen cases. As you will learn next week, there weren’t really effective treatments, so it’s a miracle how well the disease was contained. Most of my commentary on the disease will relate to the 2014 epidemic, so stay tuned to hear about it and learn with me!

Click to access TPWKY-Episode-11-Ebola.pdf

Click to access TPWKY-Episode-11-Ebola.pdf