Tiffany Lo-Art in Tanzania Internship
Ebola Virus Disease (EVD), most commonly known as just Ebola, is a rare and deadly disease in people and nonhuman primates (CDC, 2021). The viruses that cause the disease are located mainly in sub-Saharan Africa (CDC, 2021). People can become infected with the disease through direct contact with an infected animal (bat or nonhuman primate) or a sick or dead person who was infected with the Ebola virus. (CDC, 2021).
An infection with a group of viruses within the genus Ebolavirus causes it:
- Ebola virus (species Zaire ebolavirus)
- Sudan virus (species Sudan ebolavirus)
- Taï Forest virus (species Taï Forest ebolavirus, formerly Côte d’Ivorie ebolavirus)
- Bundibuygo virus (species Bundibuygo ebolavirus)
- Reston virus (species Reston ebolavirus)
- Bombali virus (species Bombali ebolavirus)
Only four (Ebola, Sudan, Taï Forest, and Bundibuygo) are known to cause disease in people (CDC, 2021). Reston virus is known to cause disease in nonhuman primates and pigs, but not in humans, whereas the Bombali virus is currently unknown to cause disease in either animals or humans (CDC, 2021).
According to the World Health Organisation, the average EVD case fatality rate is approximately 50%, although case fatality rates have varied from 25% to 90% in past outbreaks (World Health Organisation, 2021).
Transmission
Scientists believe that people are initially infected with the Ebola virus through contact with an infected animal, such as a fruit bat or nonhuman primate (CDC, 2021). After that, the virus spreads among people (CDC, 2021).
The virus is spread through direct contact, such as through broken skin or mucous membranes in the nose, eyes, or mouth, with:
- Blood of body fluids (urine, saliva, sweat, faeces, vomit, breast milk, amniotic fluid, semen) of a person who is sick with or has died from the virus
- Objects, such as clothing, bedding, needles, and medical equipment that were contaminated with body fluids from a person who is sick with or has died from the virus
- Semen from a man who recovered from the virus (through oral, vaginal, or anal sex). The virus can remain in certain body fluids of a patient who has recovered from the disease, even if they no longer have symptoms of severe illness. Currently, there is no evidence that Ebola can be spread through sex or other contact with vaginal fluids from a woman who had the virus
When people first become infected with the virus, they do not start showing or developing symptoms right away (CDC, 2021). A person can only spread Ebola to other people after they develop signs and symptoms of Ebola (CDC, 2021).
The virus is not known to be transmitted through food (CDC, 2021). However, through the handling and consumption of wild animal meat or wild animals infected with ebola, the virus can spread (CDC, 2021).
Symptoms and Ebola Diagnosis
Symptoms may occur anywhere from 2-21 days after contact with Ebola virus, with an average of 8-10 days (CDC, 2021). The illness typically progresses from “dry” symptoms such as fever, aches, pains, and fatigue to “wet” symptoms. Such as diarrhoea and vomiting when the person becomes more ill (CDC, 2021).
According to the Centers for Disease Control and Prevention, some primary symptoms of Ebola include some or several of the following:
- Fever
- Aches and pains, such as a severe headache, joint and muscle pain, and stomach pain
- Weakness and fatigue
- Diarrhea and vomiting
- Unexplained haemorrhaging, bleeding or bruising
Some other symptoms include red eyes, skin rash, and hiccups in the late stages. Many common illnesses share similar symptoms with Ebola Virus Disease, such as influenza, malaria, or typhoid fever (CDC, 2021).
Some diagnostic methods include collecting blood samples, as the Ebola virus can be detected in blood after symptoms appear. It may take up to three days after symptoms start for the virus to reach detectable levels (CDC, 2021). Another method is the Polymerase Chain Reaction (PCR), which is one of the most commonly used methods for diagnosing the virus, as it can detect low levels of the Ebola virus (CDC, 2021). However, when the virus is no longer present in high numbers in a patient’s blood, this method becomes ineffective, and other methods, based on the detection of antibodies on EVD case produces to an infection, can then be used to confirm a patient’s exposure and disease to the virus (CDC, 2021).
While Ebola is a rare disease, it is often severe and deadly, and recovery from the disease depends on the patient’s immune response and quality of clinical care (CDC, 2021). Survivors of the infection have antibodies that can be detected in the blood up to 10 years after recovery, and it is thought that survivors have some protective immunity to the type of Ebola that infected them (CDC, 2021). Ebola survivors may experience side effects after recovering from the disease, such as tiredness, muscle aches, eye and vision problems, and stomach pain (CDC, 2021).
Treatment
Currently, two treatments are approved by the U.S. Food and Drug Administration (FDA) for the treatment of Ebola Virus Disease caused by the Ebola virus, specifically Zaire ebolavirus, in adults and children (CDC, 2021). The first drug is Inmazeb™, which was approved in October 2020 (CDC, 2021). The second drug is Ebanga™, which was approved in December 2020 (CDC, 2021). Both of these treatments were evaluated in a randomized controlled trial during the 2018-2020 Ebola outbreak in the Democratic Republic of Congo (CDC, 2021). Overall, the survival rate was much higher for patients that received either of the two treatments, however, neither Inmazeb™ nor Ebanga™ have been evaluated for their efficiency against other species of ebolavirus (CDC, 2021).
Basic interventions can also significantly improve chances of survival when it is provided early, and they include:
- Providing fluids and electrolytes (body salts) orally or through infusion into the vein
- Using medication to support blood pressure, reduce vomiting and diarrhoea, and to manage fever and pain
- Treating other infections, if they occur
Prevention
According to the Centers for Disease Control and Prevention, there are a number of ways to protect yourself and prevent the spread of Ebola Virus Disease:
- avoid contact with blood and body fluids (ex: urine, faeces, saliva, vomit, sweat, breast milk, amniotic fluid, semen, and vaginal fluids) of people who are sick
- Avoid contact with items that may have come in contact with an infected person’s blood or body fluids (ex: clothes, bedding, needles, and medical equipment)
- Avoid funeral or burial services that include touching the body of someone who died from EVD or potentially EVD
- Avoid contact with bats, forest antelopes, and nonhuman primates (such as monkeys and chimpanzees) blood, fluids, or raw meat prepared from these or unknown animals (ex: bushmeat)
Currently, the Ervebo vaccine is effective in protecting people from the species Zaire ebolavirus, and in December 2020, the vaccine was approved by the US Food and Drug Administration and prequalified by the World Health Organization for use in individuals over the age of eighteen (except for pregnant and breastfeeding women) for protection caused by the Zaire ebolavirus (World Health Organization, 2021). In May 2020, the European Medicines Agency recommended granting marketing authorisation for a two-component vaccine called Zabdeno and Mvabea for individuals over the age of one (World Health Organisation, 2021). The vaccine requires two doses, where Zabdeno is first administered, while the second dose, Mvabea, is given approximately eight weeks later (World Health Organisation, 2021). The 2-dose regimen is thus unsuitable for an outbreak where immediate protection and response is vital (World Health Organization, 2021).
The Ebola virus can also survive on dry surfaces, such as doorknobs and countertops, for several hours. Therefore, cleaning and disinfection should be performed using hospital-grade disinfectant (CDC, 2021).
Outbreak Preparation
Outbreaks in nonhuman primates and antelope often precede or happen at the same time as human cases of Ebola Virus Disease (EVD) in the same or nearby areas (CDC, 2021). An example is that in 1994, the chimpanzee population in the area where the Taï National Forest outbreak occurred decreased by half (CDC, 2021). Typically, cases of Ebola in people emerge after the handling and butchering of infected animals, and once the virus spreads to humans, it quickly spreads from person to person (CDC, 2021). As such, rapid identification of cases is vital to prevent large-scale epidemics (CDC, 2021).
However, because the early symptoms of Ebola are not specific to this disease alone, it can be hard to distinguish it from other illnesses, such as malaria, influenza, leptospirosis, yellow fever, and other viruses spread by insects, or viral or bacterial infections of the intestines, such as typhoid fever (CDC, 2021). Once a case is identified, everyone who has come in direct contact with the sick patient is found—this practice is called contact tracing (CDC, 2021). The contacts are watched for symptoms of Ebola for 21 days from the last day they came in contact with the Ebola patient. If the contact develops a fever or other symptoms, they are isolated, tested, and provided care (CDC, 2021). The cycle repeats until all new contacts are identified and observed for 21 days (CDC, 2021). The World Health Organisation declares an Ebola outbreak over when two incubation periods (42 days) have passed without any new cases (CDC, 2021).
Ebola in Tanzania
While there are no officially confirmed cases of Ebola in Tanzania, many countries nearby are battling Ebola outbreaks, such as the Democratic Republic of Congo (World Health Organization, 2019; Marchione, 2021). Due to the possibility of cross-border spread and regional risk, it is highly important to remain vigilant to prevent the spread of the disease.
Sources:
Centers for Disease Control and Prevention. (2021, March 18). Ebola (Ebola Virus Disease).
Marchione, M. (2021, March 31). Man’s Ebola relapse spawned dozens of new cases in Africa
World Health Organization. (2019, October 30). Cases of Undiagnosed Febrile Illness – United Republic of Tanzania
World Health Organization. (2021, February 23). Ebola virus disease
