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Magill’s Medical Guide, 9th Edition

Ebola virus

by Soraya Ghayourmanesh

Category: Disease/Disorder

Anatomy or system affected: Blood, circulatory system, gastrointestinal system, muscles, skin

Specialties and related fields: Epidemiology, public health, virology

Definition: A virus responsible for a severe and often fatal hemorrhagic fever.

Key terms:

Filoviridae: the family to which the Ebola virus belongs

maculopapular rash: a discolored skin rash observed in patients with Ebola fever

CAUSES AND SYMPTOMS

The Ebola virus is named after the Ebola River in northern Zaire (now the Democratic Republic of the Congo), Africa. The virus was first detected in 1976, when hundreds of deaths were recorded in Zaire as well as in neighboring Sudan. Four subtypes of the virus cause human disease: Zaire, Sudan, Côte d’Ivoire (or Ivory Coast), and Bundibugyo. A fatal disease among cynomolgus laboratory monkeys that were imported from the Philippines to Texas in 1996 was caused by the Reston subtype of the virus, which causes disease in nonhuman primates and in pigs but is not believed to cause symptoms in humans. Another devastating outbreak among humans took place in early 1995 in Kikwit, Zaire, claiming the lives of 250 patients out of 315 reported cases, an 88 percent fatality rate. It is interesting to note that the epidemic ended within a few months, as suddenly as it began; this puzzled scientists, who are still not fully aware of the causes and nature of the virus. Despite the dreadful speed with which the disease killed its victims, scientists were able to contain it with a relatively small number of fatalities. Outbreaks in Africa have continued to occur, some of them severe; a 2007 outbreak in the Democratic Republic of the Congo resulted in 264 cases and 187 deaths.

The Ebola virus appears to have an incubation period of two to twenty-one days, after which time the impact is devastating. The patient develops appetite loss, increasing fever, headaches, and muscle aches. The next stage involves disseminated intravascular coagulation (DIC), a condition characterized by both blood clots and hemorrhaging. The clots usually form in vital internal organs such as the liver, spleen, and brain, with subsequent collapse of the neighboring capillaries. Other symptoms include vomiting, diarrhea with blood and mucus, and conjunctivitis. An unusual type of skin irritation known as maculopapular rash first appears in the trunk and quickly covers the rest of the body. The final stages of the disease involve a spontaneous hemorrhaging from all body outlets, coupled with shock and kidney failure and often death within eight to seventeen days.

TREATMENT AND THERAPY

The Ebola virus is classified as a ribonucleic acid (RNA) virus and is closely related to the Marburg virus, first discovered in 1967. The Marburg and the Ebola viruses are the only two identified members of the Filoviridae family, which was first established in 1987. Electron microscope studies show the Ebola virus as long filaments, 650 to 14,000 nanometers in length, that are often either branched or intertwined. Its virus part, known as the virion, contains one single noninfectious minus-strand RNA molecule and an endogenous RNA polymerase. The lipoprotein envelope contains a single glycoprotein, which behaves as the type-specific antigen. Spikes are approximately seven nanometers in length, are spaced at approximately ten-nanometer intervals, and are visible on the virion surface. It is believed that once in the body, the virus produces proteins that suppress the organism’s immune system, thus allowing its uninhibited reproduction. In 2002, researchers announced a new discovery about how Ebola makes entry into and subverts human cells. Findings show that the virus targets a “lipid raft,” tiny fat platforms that float atop the membranes of human cells. These rafts act as gateways for the virus, the assembly platform for making new virus particles, and the exit point where new particles bud. This research is a significant step toward one day creating drugs that would stop viruses from replicating.

An enlarged view of the Ebola virus that causes African hemorrhagic fever.

MMG2022_p891_001.tif

Photo by NIAID, via Wikimedia Commons.

The Ebola virus can be transmitted through contact with body fluids, such as blood, semen, mucus, saliva, and even urine and feces. It is thought that the first person in an outbreak acquires the virus through contact with an infected animal, including carcasses of dead animals.

The level of infectivity of the Ebola virus is quite stable at room temperature. Its inactivation is accomplished via ultraviolet or gamma irradiation, 1 percent formalin, beta propiolactone, and an exposure to phenolic disinfectants and lipid solvents, such as deoxycholase and ether. The virus isolation is usually achieved from acute-phase serum of appropriate cell cultures, such as the Ebola-Sudan virus MA-104 cells from a fetal rhesus monkey kidney cell line. Satisfactory results have been accomplished using tissues obtained from the liver, spleen, lymph nodes, kidneys, and heart during autopsy. The virus isolation from brain and other nervous tissues, however, has been rather unsuccessful so far. Neutralization tests have been inconsistent for all filoviruses. Ebola strains, however, show cross-reactions in tests of immunofluorescence assays.

Information on Ebola Virus

Causes: Viral infection

Symptoms: Severe blood clotting and hemorrhaging, fever, lethargy, appetite loss, headaches, muscle aches, skin rash

Duration: Acute

Treatments: None

There appears to be no known or standard treatment for Ebola fever. No chemotherapeutic or immunization strategies are available, and no antiviral drug has been shown to provide positive results, even under laboratory conditions. Human interferon, human convalescent plasma, and anticoagulation therapy have been used with unconvincing results.

At this stage, therapy involves sustaining the desired fluid and electrolyte balance by the frequent administration of fluids. Bleeding may be fought off with blood and plasma transfusion. Sanitary conditions to avoid further contact with the disease are required. Proper decontamination of medical equipment, isolation of the patients from the rest of the community, and prompt disposal of infected tissues, blood, and even corpses limit the spread of the disease.

PERSPECTIVE AND PROSPECTS

The puzzling characteristics of the Ebola virus are the location of its primary natural reservoir, its sudden eruption and quick end, and the unusual discovery of the virus in the organs of people who have survived it.

In the past, experimental work on the virus has been slow because of its high pathogenicity. The progress of recombinant deoxyribonucleic acid (DNA) technology has shed the first light on the molecular structure of this virus. It is hoped that further work using this technique as well as the results of viruses of lower pathogenicity (such as the Reston virus) will provide the desired information on replication and virus-host interactions. Finally, the improvement of the various diagnostic tools will allow more accurate virus identification and assessment of transmission modes.

In 1995, the World Health Organization (WHO) investigators and epidemiologists captured about three thousand birds, rodents, and other animals and insects that are suspected of spreading the disease in order to investigate the source of the virus. The results, however, were obscure and inconclusive, and the main facts about the disease are still a mystery, with the exception of the established link between primates and Ebola virus infection in humans. This conclusion was reached after the fatal infection of a French researcher in Côte d’Ivoire who performed an autopsy on a chimpanzee that had died from a disease with the same symptoms as Ebola fever. Yet, the human outbreaks in the Democratic Republic of the Congo and the Sudan have not been traced to primates. As long as these puzzling questions linger, the disease should be contained, with particular emphasis on the improvement of sanitary conditions and the control of body fluid contact.

See also Bleeding; Centers for Disease Control and Prevention (CDC); Dengue fever; Epidemiology; Hemorrhage; Marburg virus; Tropical medicine; Viral hemorrhagic fevers; Viral infections; Zoonoses.

For Further Information:

1 

A.D.A.M. Medical Encyclopedia. “Ebola Hemorrhagic Fever.” MedlinePlus, August 24, 2011.

2 

Balter, Michael. “On the Trail of Ebola and Marburg Viruses.” Science 290, no. 5493 (November 3, 2000): 923-25.

3 

Biddle, Wayne. A Field Guide to Germs. 2d ed. New York: Anchor Books, 2002.

4 

Dyer, Nicole. “Killers Without Cures.” Science World 57, no. 3 (October 2, 2000): 8-12.

5 

Global Alert and Response. “Ebola Haemorrhagic Fever.” World Health Organization, 2013.

6 

Jaax, Nancy. Lethal Viruses, Ebola, and the Hot Zone: Worldwide Transmission of Fatal Viruses. Lincoln: University of Nebraska Foundation, 1996.

7 

Jahrling, Peter B., et al. “Filoviruses and Arenaviruses.” In Manual of Clinical Microbiology, edited by Patrick R. Murray et al. 8th ed. Washington, DC: ASM Press, 2007.

8 

McGraw-Hill Encyclopedia of Science and Technology. 10th ed. 20 vols. New York: McGraw-Hill, 2007.

9 

Peters, C. J., and J. W. LeDuc. “An Introduction to Ebola: The Virus and the Disease.” Journal of Infectious Diseases 179, supp. 1 (1999): ix-xvi.

10 

Special Pathogens Branch. “Ebola Hemorrhagic Fever” Centers for Disease Control and Prevention, December 21, 2012.

11 

Special Pathogens Branch. “Known Cases and Outbreaks of Ebola Hemorrhagic Fever, in Chronological Order.” Centers for Disease Control and Prevention, July 31, 2012.

12 

Strauss, James, and Ellen Strauss. Viruses and Human Disease. 2d ed. Boston: Academic Press/Elsevier, 2008.

Citation Types

Type
Format
MLA 9th
Ghayourmanesh, Soraya. "Ebola Virus." Magill’s Medical Guide, 9th Edition, edited by Anubhav Agarwal,, Salem Press, 2022. Salem Online, online.salempress.com/articleDetails.do?articleName=MMG2022_0415.
APA 7th
Ghayourmanesh, S. (2022). Ebola virus. In A. Agarwal, (Ed.), Magill’s Medical Guide, 9th Edition. Salem Press. online.salempress.com.
CMOS 17th
Ghayourmanesh, Soraya. "Ebola Virus." Edited by Anubhav Agarwal,. Magill’s Medical Guide, 9th Edition. Hackensack: Salem Press, 2022. Accessed October 22, 2025. online.salempress.com.