Ebola Virus: Transmission, Symptoms, Diagnosis, Treatment and Prevention

Ebola virus is a severe viral hemorrhagic fever that affects human beings and other primates. Learn about its transmission, symptoms, diagnosis, treatment and prevention. Understand the role of agent, host and environmental factors in the spread of the virus. Get insights into clinical diagnosis and available treatments.

Ebola virus 1
Ebola virus
Ebola is a serious virus disease which affects human beings and other primates. Ebola is
said to be a viral hemorrhagic fever due to its severity and fatality in human beings. The rates of
fatality of this virus vary and are dependent on the strain. This viral disease first emerged in 1976
in Sudan and Zaire, and since then, there have been at least 10 outbreaks in different regions (Li
and Chen 2014). The disease has since then been a very common outbreak disease in the tropical
regions of sub-Saharan Africa. These include Guinea, Gabon, Democratic Republic of Congo
(DRC), Uganda, South Sudan, Nigeria, Mali, Senegal, Sierra Leone, Liberia, and Ivory Coast. In
2019, the intensity of transmission of this virus in the DRC has remained substantial. According
to World Health Organization (WHO) (2019), 3054 cases have been reported in DRC as of 4th of
September 2019 with 2945 confirmed cases, 109 probable cases of which 2052 have been death
cases with an overall case fatality ratio of 67%.
Transmission of Ebola
Ebola virus is usually transmitted to people through different means. According to
Malvy, McElroy, de Clerck, Günther, and van Griensven (2019), the most common form of
transmission of this virus is primarily through having a direct contact with the infected body
fluids and corpses. The fluids that may contain Ebola virus include mucus, saliva, vomit, feces,
sweat, tear, breast milk, urine and semen. In a situation where the there is lack of enough
resources, this contact can result into a major epidemic. The entry points of this deadly disease
are the nose, mouth, open wounds, cuts and abrasions, eyes, and even larger droplets. Osterholm
et al. (2015) argue that this virus is capable of surviving in dried state objects for a few hours and
few days on the body fluids which are outside human beings. This makes having contact with

Ebola virus 2
objects and surfaces that have been contaminated by the Ebola virus a mode of transmission of
the infection. Research conducted by Mate et al. (2015) reveals that Ebola virus is capable of
persisting in semen after recovery for more than 3 months. Therefore, sexual intercourse with an
infected person can result into an infection. Dead bodies and animals are very infectious and the
people handling them must take necessary precautions when disposing them off. Traditional
burial ceremonies and embalming are not recommended as they highly expose people to the
infections. Although there are no clear circumstances on how Ebola virus initially spread from
animals to human beings, it is believed that it is spread through direct contact with an infected
animal or fruit bat. Health care workers are also at risk of contracting Ebola especially when lack
appropriate protective gears, when they fail to properly handle the contaminated surfaces,
clothing and objects, when they do not properly wear their protective gears. It is important to
note that a person who has Ebola but has no symptoms of the disease cannot spread it (Lo,
Marston, Dahl and De Cock 2017). Although there has been several investigations done on this
disease, it is only believed to be a zoonotic but its natural reservoir has not yet been determined.
Signs and symptoms
The incubation period of Ebola virus ranges from 2 to 21 days after infection (Holmes,
Dudas, Rambaut and Andersen 2016). The symptoms of this disease are non-specific therefore
making the clinical diagnosis difficult. However, there are certain symptoms that can be used for
diagnosis. The early symptoms of this disease include fatigue, fever, joint and muscle pain, sore
throat, lack of appetite, weakness, and headache. The later symptoms of this disease include
vomiting, diarrhea, nausea, stomach pain, unexplained bruising for instance bloody nose,
bloodshot eyes, bloody urine, and bloody diarrhea. Some patients may also experience rash,
hiccups, cough, chest pain, difficulty in breathing, difficulty in swallowing and bleeding inside

Ebola virus 3
and outside the body. The fatality rate of Ebola virus is between 40% to 90% depending on
different factors like the species of the virus and the age of an individual (Kucharski and
Edmunds 2014). It is important to note that once the symptoms start showing, then the infected
individual is highly contagious and must be isolated so as to prevent further transmission. Also,
the people who survive are still contagious for 21-42 days after the symptoms go away
(Kucharski and Edmunds 2014). Mental confusion can also be a sign of Ebola virus infection.
Role of agent, host and environmental factors
Ebola virus disease is one of the hemorrhagic fevers caused by an infection with a virus
of the Filoviridae family of the genus Ebolavirus in the order of Mononegavirales (Malvy et al.
2019). In this genus, the genome of the viruses has a single strand of RNA enveloped in a lipid
membrane which consists of a negative polarity. The filovirus particles are known to form a long
and in some cases branched filaments of different shapes and sizes. Ebolavirus genus has five
different species of taxonomic designations. These include the Bundibugyo ebolavirus
(Bundibugyo virus), the Reston ebolavirus (Reston virus), Sudan ebolavirus (Sudan virus), Taï
Forest ebolavirus (Taï Forest virus), and Zaire ebolavirus (Ebola virus) (Malvy et al. 2019).
However, not all of them have been associated with the outbreak of diseases in human beings.
The only viruses which have so far been proved to cause diseases in human beings are Sudan,
Bundibugyo and Zaire ebolaviruses (Center for Disease Control and Prevention (CDC) n.d). The
Reston virus although pathogenic is found in nonhuman primates. On the other hand, there has
been an evolutionary overlap of rates with other viruses of RNA. Hoenen et al. (2015) argue that
the genomes of viruses from at least 5% of all the cases that have been reported have been
sequenced thereby allowing the reconstruction of Ebola virus across country borders.

Ebola virus 4
There are also few adaptive mutations which including alanine to valine which enhances
the entry of the virus into the cells of human beings during the outbreak of a strain. Upon
entering the body in an enclosed package which contains RNA, the virus specifically targets the
cells of the liver, the cells of the immune system as well as the cells of the endothelial tissues, all
of which are in line with the blood vessels. It is important to note that the virus gets into these
cells by travelling through the cell membrane, a barrier which offers protection from the cell’s
environment. Macropinocytosis, an engulfing process which allows the cell membrane to be
consumed by the virus after entering the cells through one of the pathways of nutrients intake
enables the Ebola virus cells to replicate (Tseng and Chan 2015). This in turn limits the proper
functioning of these cells or even their death. Once the virus is replicated, it then buds its viral
pieces so as to form its own cell membrane to make a capsule so as to enable its safe travel to the
nearby cells.
Ebola virus is capable of making its own protein known as the Ebola virus glycoprotein
which disrupts the adhesion of cells once it is inside (Bornholdt et al. 2016). When the cells have
difficulty in sticking together, the blood vessels start leaking hence hemorrhage as well as
internal bleeding. The virus targets the cells of the liver because it reduces its ability to clear the
toxic waste of the body thereby causing a compromise on the bloodstream as well as infecting
the immune system of the body. This leads to a rapid increase of the virus in the body area of
infection. With time, the infection can lead to severe loss of electrolytes, blood plasma and fluids
due to excessive bleeding, diarrhea and vomiting (Smith, Rawlinson, Kok, Dwyer and Catton
2015). It is important to note that the survival of Ebola virus highly depends on the host
mechanism. Human beings are not the host mechanism of this virus although they get infected
when they come into contact with the infected host.

Ebola virus 5
Clinical diagnosis
It is difficult to diagnose the early signs of Ebola virus disease as they are similar to other
similar hemorrhagic infections. The differential diagnosis of Ebola virus disease includes
malaria, yellow fever, typhoid fever and other hemorrhagic and bacterial infections (Broadhurst,
Brooks and Pollock 2016). Therefore to ensure that a proper diagnosis is achieved, it is important
to assess the history of the patient including having any contact with a dead or sick animal,
having any contact with a suspected, having any kind of contact with contaminated objects and
surfaces, having sexual intercourse with a man who has recovered from Ebola virus disease,
taking breast milk from a woman who has recovered from Ebola virus disease, probable or even
a confirmed Ebola virus disease patient before 21 days of the onset of the symptoms. To
ascertain that a patient is suffering from Ebola virus disease, laboratory diagnosis must be carried
out under maximum biological containment conditions (Broadhurst et al. 2016). This is to ensure
that safe and expeditious strategies of testing the virus are highly established. Ebola virus can be
found in the bloodstream immediately after the onset of the symptoms especially fevers.
However, the detectable levels of this virus may take up to three days.
The detection of antigens as well as conducting molecular tests has proved to be effective
ways of diagnosing Ebola virus disease (Public Health Laboratory Network 2014). There are
some diagnostics which are purposely meant for detecting the Ebola virus and those that that
purposely differentiate the different types of Ebola virus. According to Broadhurst et al. (2015),
to determine if there is current or even prior Ebola virus disease infection, serological assays of
detecting specific antiviral antibodies in the serum of a patient can be used. This entails
irradiating the infected serum suspensions or cell cultures and incubating with the probable
exposures by using an indirect fluorescent antibody detection test (IFAT), and enzyme-linked

Ebola virus 6
immunosorbent assay tests (ELISA) (Kaushik, Tiwari, Jayant, Marty and Nair 2016).ELISA can
also used for the detection of protein-antigen of the Ebola virus. Other diagnosis includes the use
of an electron microscopy, reverse transcriptase polymerase chain reaction (RT-PCR) assay,
antigen-capture detection tests, and serum neutralization test. When selecting a diagnostic test
kit, a healthcare practitioner must consider the technical specifications of the kit, the incidence
and prevalence of the disease, the medical and social implications of the results of the test to be
conducted (WHO n.d). An individual who shows signs of Ebola virus disease or even a possible
exposure must be isolated and the public health authorities must be notified. A positive
laboratory test is an indication of the presence of Ebola virus infection and therefore the public
health authorizes must conduct investigations and determine every possible exposure of any
contact.
Treatment
The signs and symptoms of Ebola virus disease are usually treated as they appear so as to
prevent further escalation or even more fatal incidences. Also, the chances of survival are
significantly increased if the basic supportive care is administered immediately after the
detection. These include infusing body salts into the veins, offering oxygen therapy, treating
other infections if they occur, using medication to support blood pressure, reduce vomiting and
diarrhea, and managing fever and pain.
There are several clinical treatments which are under experiment for the treatment of
Ebola virus disease; however, none of them have been approved for full-scale production or even
treatment of human beings. According to Henao-Restrepo et al. (2015), there are non-virulent
portions of a vaccine used to train the body on how to detect an Ebola virus as well as protect the

Ebola virus 7
body against such a virus in case there is an infection. One example is the one produced by
rVSV-ZEBOV. Since the vaccines have not licensed, WHO have warranted their uses in the
Ebola virus disease epidemics by laying out emergency protocols on its use as well as cautiously
finding ways to expand its reach to the infected populations.
Another treatment which is still being developed involves the usage of genetic materials
in small fragments. These genetic materials are called small interfering RNAs (siRNA). Henao-
Restrepo et al. (2015) argue that the RNA’s small particles have been devised to match the
specific pieces of the RNA of the Ebola virus. The siRNA is used to slow down the replication
of Ebola virus by sticking to it. If the siRNA sticks to the Ebola virus RNA, then new Ebola
particles cannot be created (Bishop 2015). This vaccine was approved for use in the year 2014
outbreak.
The use of antibodies is a treatment that has been widely used especially on healthcare
workers. According to Bishop (2015), antibodies are used because it has the large and Y-shaped
to recognize and neutralize viruses in the body. Currently, the most developed drug is known as
ZMapp, a cocktail of three different antibodies. Group and Multi-National PREVAIL II Study
Team (2016) argue that ZMapp neutralizes the glycoprotein which is the specific key and
subsequently keeps the virus out of the cell. This is because ZMapp is made up of monoclonal
antibodies which render the Ebola virus harmless by binding it. Although Zmapp is capable of
treating Ebola virus disease, it does not grant an ultimate resistance to the virus. A report as at
12th august 2019 however shows that 49% of patients who received ZMapp died (WHO 2019).
It is important to note that the recovery from Ebola virus disease depends on good
supportive care as well as the immune response of the patient. The use of mAb114 and REGN-

Ebola virus 8
EB3, all of which are a cocktail of three monoclonal antibodies have currently been
recommended because they have showed increased survival rates. WHO (2019) have found that
only 29% for REGN-EB3 and 34% on mAb114 deaths of patients were reported. Clinical trials
are however still being conducted to determine their safety.
Prevention
The prevention of Ebola virus disease highly focuses on avoiding any kind of contact
with the virus. One prevention measure is avoiding bush meat. Although thorough cooking kills
the virus, the preparation process exposes individuals as they come into contact with the animal’s
body fluids. Following the infection-control procedures is also a very vital preventive measure.
Usually, the healthcare professionals are exposed and such measures will help protect them from
the disease. Using appropriate and safe equipments to handle the remains of infected corpses is
also a prevention technique. This is because these bodies are still highly contagious. Healthcare
providers should also avoid coming into contact with the infected bodies, surfaces and objects.
The objects and clothing used should equally be disposed off appropriately. People should also
avoid traveling to the known areas of outbreak. However, in case individuals visit these places,
they should monitor their health in the first 21 days of their return. Also, infected persons must
be isolated and strict nursing barriers be used. The non-disposable equipment used must also be
properly disinfected.
Potential policy responses
World Health organization has partnered with different policy makers, Non-
governmental organizations and governments of the affected countries so as to come up with
policy and response plans to ensure that there is maximum coordination among all the actors of

Ebola virus 9
the delivery of effective care and support. The goal of policy response is to stop the transmission
of Ebola virus disease as well as prevent its spread. The response policies focus on three pillars
and activities. These include interventions focusing on immediate response to an outbreak
include assessment, and taking possible effective measures in reducing the spread and
interrupting possible transmission of the disease, improving on collaboration and coordination by
building on the local, regional and national coordination, encouraging the whole society to
positively respond, and promoting proactive preparedness of the neighboring countries, as well
as scaling up the mobilization of financial and human resources through training and social
mobilization, encouraging communication and public engagement, linking health and social care
responses. In case of an outbreak, WHO must respond immediately and take actions that support
the affected countries as well as intervene in the neighboring countries so as to enhance
preparedness and prevent an outbreak of Ebola virus disease. It is also recommended that in case
of an outbreak, all governments of the affected countries must establish a national task force for
Ebola outbreak response and the government must declare the Ebola virus disease as a threat to
national health (Calnan, Gadsby, Kondé, Diallo and Rossman 2018). The task force must ensure
effective coordination of the outbreak response activities; strengthen early detection, reporting of
cases, investigate and actively survey, create public awareness and institute prompt and effective
management of the disease.
Conclusion
Ebola virus is a serious epidemic disease which is mostly common in some parts of
Africa. This disease is transmitted through coming into contact with an infected object, fluid of
an infected person or an infected dead body. Although the host of this virus has not yet been
determined, people in the affected countries must take the precaution measures into

Ebola virus 10
consideration so as to prevent being infected. The common symptoms include fever, diarrhea,
vomit, bleeding and chest pains. However, these signs and symptoms cannot be used to conclude
that it is Ebola since the Ebola virus disease has several differential illnesses. People found to be
sick from Ebola must immediately be isolated so as to prevent further spread of the disease. The
treatment of Ebola virus has not yet been determined, however, there are vaccines and treatments
which have been found to be highly effective despite still registering few numbers of deaths.

Ebola virus 11
List of References
Bishop, B. M. (2015). Potential and emerging treatment options for Ebola virus disease. Annals
of Pharmacotherapy, 49(2), 196-206. https://doi.org/10.1177/1060028014561227
Bornholdt, Z.A., Ndungo, E., Fusco, M.L., Bale, S., Flyak, A.I., Crowe, J.E., Chandran, K. and
Saphire, E.O., 2016. Host-primed Ebola virus GP exposes a hydrophobic NPC1 receptor-binding
pocket, revealing a target for broadly neutralizing antibodies. MBio, 7(1), pp.e02154-15.
DOI: 10.1128/mBio.02154-15
Broadhurst, M.J., Brooks, T.J. and Pollock, N.R., 2016. Diagnosis of Ebola virus disease: past,
present, and future. Clinical microbiology reviews, 29(4), pp.773-793.
DOI: 10.1128/CMR.00003-16
Broadhurst, M.J., Kelly, J.D., Miller, A., Semper, A., Bailey, D., Groppelli, E., Simpson, A.,
Brooks, T., Hula, S., Nyoni, W. and Sankoh, A.B., 2015. ReEBOV Antigen Rapid Test kit for
point-of-care and laboratory-based testing for Ebola virus disease: a field validation study. The
Lancet, 386(9996), pp.867-874. https://doi.org/10.1016/S0140-6736(15)61042-X
Calnan, M., Gadsby, E.W., Kondé, M.K., Diallo, A. and Rossman, J.S., 2018. The response to
and impact of the Ebola epidemic: towards an agenda for interdisciplinary
research. International journal of health policy and management, 7(5), p.402.
doi:10.15171/ijhpm.2017.104
Centers for Disease Control and Prevention. Ebola virus disease distribution map: cases of Ebola
virus disease in Africa since. Retrieved from https://www.cdc.gov/vhf/ebola/history/distribution-
map.html

Ebola virus 12
Henao-Restrepo, A.M., Longini, I.M., Egger, M., Dean, N.E., Edmunds, W.J., Camacho, A.,
Carroll, M.W., Doumbia, M., Draguez, B., Duraffour, S. and Enwere, G., 2015. Efficacy and
effectiveness of an rVSV-vectored vaccine expressing Ebola surface glycoprotein: interim results
from the Guinea ring vaccination cluster-randomised trial. The Lancet, 386(9996), pp.857-866.
https://doi.org/10.1016/S0140-6736(15)61117-5
Holmes, E.C., Dudas, G., Rambaut, A. and Andersen, K.G., 2016. The evolution of Ebola virus:
Insights from the 2013–2016 epidemic. Nature, 538(7624), p.193. doi:10.1038/nature19790
Group, T.P.I.W. and Multi-National PREVAIL II Study Team, 2016. A randomized, controlled
trial of ZMapp for Ebola virus infection. The New England journal of medicine, 375(15), p.1448.
Hoenen, T., Safronetz, D., Groseth, A., Wollenberg, K.R., Koita, O.A., Diarra, B., Fall, I.S.,
Haidara, F.C., Diallo, F., Sanogo, M. and Sarro, Y.S., 2015. Mutation rate and genotype
variation of Ebola virus from Mali case sequences. Science, 348(6230), pp.117-119. DOI:
10.1126/science.aaa5646
Kaushik, A., Tiwari, S., Jayant, R.D., Marty, A. and Nair, M., 2016. Towards detection and
diagnosis of Ebola virus disease at point-of-care. Biosensors and Bioelectronics, 75, pp.254-272.
doi:10.1016/j.bios.2015.08.040
Kucharski, A.J. and Edmunds, W.J., 2014. Case fatality rate for Ebola virus disease in west
Africa. The Lancet, 384(9950), p.1260. DOI:https://doi.org/10.1016/S0140-6736(14)61706-2
Li, Y.H. and Chen, S.P., 2014. Evolutionary history of Ebola virus. Epidemiology &
Infection, 142(6), pp.1138-1145. DOI: https://doi.org/10.1017/S0950268813002215

Ebola virus 13
Lo, T.Q., Marston, B.J., Dahl, B.A. and De Cock, K.M., 2017. Ebola: anatomy of an
epidemic. Annual review of medicine, 68, pp.359-370. https://doi.org/10.1146/annurev-med-
052915-015604
Malvy, D., McElroy, A.K., de Clerck, H., Günther, S. and van Griensven, J., 2019. Ebola virus
disease. The Lancet. DOI:https://doi.org/10.1016/S0140-6736(18)33132-5
Mate, S.E., Kugelman, J.R., Nyenswah, T.G., Ladner, J.T., Wiley, M.R., Cordier-Lassalle, T.,
Christie, A., Schroth, G.P., Gross, S.M., Davies-Wayne, G.J. and Shinde, S.A., 2015. Molecular
evidence of sexual transmission of Ebola virus. New England Journal of Medicine, 373(25),
pp.2448-2454. DOI: 10.1056/NEJMoa1509773
Osterholm, M.T., Moore, K.A., Kelley, N.S., Brosseau, L.M., Wong, G., Murphy, F.A., Peters,
C.J., LeDuc, J.W., Russell, P.K., Van Herp, M. and Kapetshi, J., 2015. Transmission of Ebola
viruses: what we know and what we do not know. MBio, 6(2), pp.e00137-15.
https://mbio.asm.org/content/mbio/6/2/e00137-15.full.pdf
Public Health Laboratory Network., 2014. Laboratory procedures and precautions for samples
collected from patients with suspected viral haemorrhagic fevers. Canberra: Australian
Government Department of Health. Retrieved
from http://www.health.gov.au/internet/main/publishing.nsf/Content/cda-pubs-other-vhf.htm.
Smith, D.W., Rawlinson, W.D., Kok, J., Dwyer, D.E. and Catton, M., 2015. Virological
diagnosis of Ebolavirus infection. Pathology, 47(5), pp.410-413.
https://doi.org/10.1097/PAT.0000000000000292

Ebola virus 14
Su, S., Wong, G., Qiu, X., Kobinger, G., Bi, Y. and Zhou, J., 2016. Diagnostic strategies for
Ebola virus detection. The Lancet Infectious Diseases, 16(3), pp.294-295.
DOI:https://doi.org/10.1016/S1473-3099(16)00049-9
Tseng, C.P. and Chan, Y.J., 2015. Overview of Ebola virus disease in 2014. Journal of the
Chinese Medical Association, 78(1), pp.51-55. https://doi.org/10.1016/j.jcma.2014.11.007
World Health Organization., 2019. Emergencies preparedness, response. Ebola virus disease –
Democratic Republic of the Congo. Retrieved from https://www.who.int/csr/don/06-september-
2019-ebola-drc/en/
World Health Organization. Ebola virus disease. Retrieved from https://www.who.int/news-
room/fact-sheets/detail/ebola-virus-disease
World Health Organization., 2019. Update on Ebola drug trial: two strong performers identified.
Retrieved from https://www.who.int/news-room/detail/12-08-2019-update-on-ebola-drug-trial-
two-strong-performers-identified