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Ebola
Overview

Ebola

Previously known as Ebola Hemorrhagic fever, Ebola Virus Disease can be caused by four distinct viruses that belong to the Filoviridae family. Members of the Ebola virus species include Ebola virus, Sudan virus, Tai Forest virus, and Bundibugyo virus. A fifth member of this family exists and it is known as the Reston virus. So far, it has only caused disease in nonhuman primates and pigs.

History according to CDC [1]

History according to CDC [1]

The first documented case of Ebola Virus Disease (EBV) occurred in 1976 when two outbreaks occurred in Sudan and the Democratic Republic of Congo (DRC). In the DRC, the cases emerged from a village near the Ebola River, and hence the name Ebola was given to the discovered virus. The outbreak in Sudan was caused by the Sudan Virus. In 1977, 1 individual was infected with the Sudan virus in the village of Tindala, DRC. A small outbreak occurred in 1979 in the same Sudanese region as the outbreak of 1976. 34 cases were reported resulting in 22 deaths. Since the original outbreak of 1976, several others have occurred which have been confined to the continent of Africa, with the exception of the latest outbreak which has resulted in cases in the US.

The Reston virus was discovered in 1989 when monkeys housed in a Reston, Virginia research facility became ill. The virus was discovered again in monkeys in Virginia and Texas in 1990. During this episodes, 4 workers in the facilities contracted the virus but did not show any symptoms. It was then determined that the Reston virus did not cause disease in humans. The Reston virus made several more appearances in nonhuman primates and even pigs in 2008.

Current outbreak

Current outbreak

According to the CDC, the outbreak of 2014 is the largest Ebola outbreak in recorded history. It is thought to originate from Guinea where the presumed index case is believed to be a 2-year-old boy in December 2013. In March of the following year, the WHO reported that the Guinean Ministry of Health had officially announced an outbreak of Ebola. From Guinea, the disease spread to neighboring Liberia followed by Sierra Leone.
On July 25, Nigeria reported its first Ebola death and ultimately the country reported 20 cases. On October 20th, the WHO declared Nigeria to officially be Ebola free.

For the first time in recorded history, Senegal reported a case of Ebola as well. The patient was a Guinean man who ultimately recovered. On October 17th, Senegal was declared Ebola fee by the WHO.

Two health care workers from Spain also contracted the disease in Africa and were transported back to Spain for treatment. The workers ultimately died and a nurse involved in their care contracted the disease in Spain. This was the first case of Ebola to be contracted outside of Africa.

WHERE DOES EBOLA COME FROM?

WHERE DOES EBOLA COME FROM?

Scientists cannot say for sure, but the virus is thought to originate from bats, which are thought to be reservoirs [2], i.e. they carry the virus but do not get sick from it. In many parts of Africa, due to cultural practices or financial reasons, the consumption of bush meat is rather common. Bush meat, like monkeys and bats, are thought to harbor the virus and can infect individuals if the come into contact with their infected body fluids.

WHAT DOES EBOLA DO TO THE BODY?

WHAT DOES EBOLA DO TO THE BODY?

According to an article published in Science Magazine [4], the Ebola viruses target dendritic cells. These cells are integral members of our immune system and typically alert the body’s T-cells that an infection has occurred. The T-cells that coordinate an attack against the invading microbe. Without an adequate immune response, the virus is allowed to reproduce without interference. A second effect, the virus can have on our immune system, is to block the interferon pathway [5]. This molecular pathway is responsible for stimulating immune cells to attack virus-infected cells in the body. Additionally, the virus in ingested by macrophages and when inside the cells, causes them to release nitric oxide which causes the blood vessels in the body to become leaky and more likely to bleed.

The Ebola viruses do more than just attack the body’s immune system. It attacks the liver, which makes proteins that are involved in blood clotting; this attribute makes a person more likely to bleed from various parts of the body. It also infects the intestinal tract, which causes diarrhea, and in many cases this is what leads to death due to dehydration or shock. Ebola also attacks collagen [6] which is the structure that holds the body’s organs together.

Treatment of Ebola

Treatment of Ebola

Because of the rarity of this disease, treatment for this is largely supportive. The mainstay of treatment is intravenous fluid replacement to replenish the volume that is lost from diarrhea, vomiting, and/or bleeding [7-10]. Electrolyte concentrations must also be monitored and replenished accordingly. Additionally, treatment to manage nausea, vomiting, diarrhea, and fever can also be given [11].

Experimental Treatments

Experimental Treatments

A variety of experimental therapies have been tried in the wake of the current and past Ebola outbreaks. Administering blood or blood products from recovered Ebola patients has been tried although results can vary [12,13]. A new drug that is a combination of three antibodies that target surface proteins of the virus is currently being used and is called Zmapp. This drug was administered to two healthcare workers in the US and both survived. Two other patients were given the treatment but did not.
Individuals who have been diagnosed with Ebola should be placed under isolation. Healthcare workers involved in the treatment of such patients must be educated on the proper use of personal protective equipment or PPE. The body should never be exposed and care should also be taken when removing and discarding PPE.

1. “Outbreaks Chronology: Ebola Virus Disease.” Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 22 Oct. 2014. Web. 31 Oct. 2014. .

2. “American Society for MicrobiologyJournal of Virology.” Ebola Virus Pathogenesis: Implications for Vaccines and Therapies. N.p., n.d. Web. 30 Oct. 2014. .
4″What Does Ebola Actually Do?” Science/AAAS. Web. 1 Nov. 2014.

4. Shabman, Reed S. “The Ebola Virus VP24 Protein Prevents HnRNP C1/C2 Binding to Karyopherin α1 and Partially Alters Its Nuclear Import.”The Journal of Infectious Diseases 204.Supplement 3. Filoviruses (2011): n. pag. JSTOR. Web. 01 Nov. 2014. .

5. “What Does Ebola Do to the Body? | MD-Health.com.” What Does Ebola Do to the Body? | MD-Health.com. N.p., n.d. Web. 01 Nov. 2014. .

6. Ribner BS. Treating patients with Ebola virus infections in the US: lessons learned. Presented at IDWeek, October 8, 2014. Philadelphia PA

7. Fowler RA, Fletcher T, Fischer WA 2nd, et al. Caring for critically ill patients with Ebola virus disease. Perspectives from west Africa. Am J Respir Crit Care Med 2014; 190:733.

8. Kreuels B, Wichmann D, Emmerich P, et al. A Case of Severe Ebola Virus Infection Complicated by Gram-Negative Septicemia. N Engl J Med 2014.

9. Lamontagne F, Clément C, Fletcher T, et al. Doing Today's Work Superbly Well – Treating Ebola with Current Tools. N Engl J Med 2014; 371:1565.

10. Centers for Disease Control and Prevention. Checklist for patients being evaluated for Ebola virus disease (EVD) in the United States https://www.cdc.gov/vhf/ebola/pdf/checklist-patients-evaluated-us-evd.pdf (Accessed on October 24, 2014).

11. World Health Organization.Statement on the WHO consultation on potential Ebola therapies and vaccines. https://www.who.int/mediacentre/news/statements/2014/ebola-therapies-consultation/en/ (Accessed on September 09, 2014).

12. World Health Organization. Experimental therapies: growing interest in the use of whole blood or plasma from recovered Ebola patients (convalescent therapies). https://www.who.int/mediacentre/news/ebola/26-september-2014/en/ (Accessed on September 29, 2014