Ebola

First discovered near the Ebola River in present day Democratic Republic of the Congo in 1976, Ebola virus disease (EVD) or Ebola hemorrhagic fever (EHF), is a rare but deadly disease caused by Ebola virus. It is known to affect mostly humans and other primates, with four of the five of the Ebola viruses infecting humans.Since it was first discovered, several outbreaks have been reported, with most of them taking place in Africa. The mortality rate for the outbreaks has varied form 25% to 90%, and currently, there is no known cure.2

Transmission

Ebola is oftentimes transmitted by contact with the bodily fluids of an infected person or animal, which can be alive or dead. This typically occurs through contact with blood, semen, or urine from an infected body or contact with objects such as needles or syringes that contain infected bodily fluid. Additionally, Ebola can be transmitted from sexual contact with an infected person whether it be through vaginal,  anal, or oral sex.​Ebola has been found within the semen of men who were previously infected, but recovered. It is unknown how long the virus can linger in semen. The disease can also spread from animal to human, with some people contracting the disease through contact with an infected fruit bat or primate. Ebola is not spread through air, water, or food, but if an infected animal is consumed, it will mostly result in infection. Healthcare workers who look after infected patients are the ones who are at highest risk for infection, due to a lack of proper protection and disposal of contaminated equipment.3

 

Symptoms and Diagnosis

Ebola has an incubation period of 2 to 21 days. The first signs of Ebola include the onset of flu-like symptoms such as the following:3

·  High fever (over 101° F or 38.3° C)

·  Fatigue

·  Headache

·  Joint and muscle aches

·  Sore throat

·  Weakness

·  Stomach pain

·  Loss of appetite3

Early diagnosis can be misleading as early symptoms are usually mild and similar to symptoms of other diseases such as typhoid fever or malaria, but becomes increasingly worse as time passes. Later symptoms include the following:

  • Diarrhea

  • Rashes

  • severe weight loss

  • Bruising

  • external and internal bleeding

Typically, death occurs about 6 to 16 days after onset of symptoms and is usually due to low blood pressure from high amounts of blood loss (hemorrhage). Death is often preceded by shock or tachycardia (rapid heart rate) and patients sometimes enter a coma before succumbing. On the other hand, for patients who are able to survive, recovery usually occurs 7 to 10 days after the appearance of symptoms. The recovery process includes a long period of reported fatigue, weakness, low appetite, and weight loss.4

If symptoms are caught early enough, diagnosis can be performed using a antigen-capture enzyme-linked immunosorbent assay (ELISA) test, which isolates proteins of the virus, a polymerase chain reaction (PCR), which isolates RNA of the virus, and an isolation of the virus itself.  In the later stages of the disease or during recovery, tests identifying the presence of IgM and IgG antibodies are used. Once a person has died, PCR and virus isolation tests are used to determine if Ebola virus was present.3

Treatment

Ebola is a relatively new disease and a cure has not been found yet. Instead, patients are provided with supportive care such as hydration, replacement of electrolytes, supplying of nutrition and oxygen, blood transfusion, and maintaining steady blood pressure and are kept in isolation rooms. Although there is no current cure, possible treatments are being developed.

ZMapp

One of these treatments is a drug called ZMapp, a mix of  three different monoclonal antibodies ( proteins in blood that attack bacteria and viruses). These antibodies are produced by specially bioengineered tobacco plants and when ZMapp was tested on nonhuman primates, it was found that they were protected for up to five days before succumbing to Ebola.5 During the 2014  West Africa Ebola Outbreak, ZMapp was used for the first time on humans. The drug was administered under emergency use to two American medical workers, three African doctors, and a Spanish priest. Aside from the priest who died, all other subjects showed improvement after the administration of ZMapp, marking the first time that a drug has been effective against Ebola.6 This momentous event was clouded by controversy due to the fact that the extremely scarce treatment was used on Americans and Europeans immediately rather than African patients who had been infected for longer. This controversy has sparked conversation on fair distribution on this potentially life-saving drug.7

Favipiravir

Another experimental drug, Favipiravir, has been successfully tested on mice infected with Ebola. During the 2014 West Africa Ebola outbreak, it was administered on an infected French nurse, along with several other experimental treatments, who made a full recovery.8 In 2014, clinical trials were performed in Guinea, but results were not able to conclusively prove the efficacy of Favipiravir. The drug did not seem to have much of an effect on patients with higher levels of Ebola virus in their blood, but it seemed fairly safe in patients with lower levels, although more research is still being conducted.9

Melatonin

Researchers are also looking into the uses of melatonin, a hormone that influences sleep, to help treat Ebola. Studies have found that melatonin directly targets the immuno-inflammatory (inflammation caused by antibodies) effects of the virus. Because melatonin is a natural substance, it does not have as high risks as other experimental treatments and will hopefully be implemented into treatments to increase their effectiveness and safety.10

STRIVE

In 2015, the Center for Disease Control (CDC), the College of Medicine and Allied Health Sciences, University of Sierra Leone, and the Ministry of Health and Sanitation launched the Sierra Leone Trial to Introduce a Vaccine to Ebola (STRIVE). This program was created as a response to the 2014 West Africa Ebola outbreak and aims to test the effectiveness of Ebola vaccine rVSV-ZEBOV among healthcare workers. Participants were randomly selected to receive the vaccine and and were regularly checked up on for 12 months. As of 2016, no Ebola related events have occurred among the participants; however, efficiency of the vaccine cannot be concluded just yet due the small sample size used in the study.11

Prevention

Because Ebola is easily spread, a patient or a suspected patient must be isolated andhealthcare workers must follow standard personal protective  equipment (PPE) which consists of double gloves,a long gown that completely covers the body, a face mask, eye protection, a head cover, and boots. Healthcare workers are also strongly advised to wash their hands before and after interacting with patients as well as after being exposed to any amount of contaminated blood. Contaminated needles and syringes must be disposed of immediately after use.3

Community education and awareness is essential to preventing future Ebola outbreaks. Raising awareness of risk factors and taking protective measures against them will reduce rates of human transmission. The critical areas of education for outbreak prevention include the following:12

 

  • Decreasing the risk of wildlife-to-human transmission from contact with infected fruit bats, monkeys, apes, and the consumption of their raw meat.

  • Reducing the risk of human-to-human transmission from close or direct contact with people who are experiencing Ebola symptoms.

  • Enforcing rigorous outbreak containment measures, including safe burial of the dead, identification of people who have come in contact with the virus, and good hygiene habits.12

 

Outsiders visiting Ebola-infected areas are advised to do the same, and are strongly encouraged to monitor their health for at least 21 days after returning home. Visitors should immediately contact a health professional if any symptoms develop. Another important method of prevention is contact tracing. Contact tracing is when every individual that an Ebola patient has come in contact with is traced down and monitored for symptoms for up until 21 days from the last day they were in contact with the infected person. If a traced person develops symptoms, they are immediately isolated and everyone they have come in contact with is traced down, and the cycle continues. This method ensures that infected people are identified and isolated immediately, stopping the spread of the disease and providing treatment as early as possible.3

West African Ebola Epidemic

The West African Ebola Epidemic, which lasted from 2013 to 2016, is the worst Ebola outbreak to date. It spread over Guinea, Sierra Leone, and Liberia, even making its way to the United States and a few European countries. 28,652 cases were reported, with 11,325 deaths, with 2 in 5 people who contracted the disease dying.3 Researchers traced the start of the outbreak to a two year old boy in Meliandou, Guinea who had died of the disease in December 2013. By March 2014,  Ebola had spread throughout several parts of the country, eventually reaching Conakry, marking the first time ever that the disease has reached the capital of a West African nation. Infection continued to surge with more than 100 new cases being reported from March to April 2014. The disease spread quickly into nearby nations, with Ebola appearing in Liberia by the end of March, in Sierra Leone by May, and in Nigeria by July. By August of that year, the World Health Organization (WHO) declared a state of emergency.13

On October 1 the first case of Ebola in the United States was reported. Thomas Eric Duncan had been traveling in Liberia when he contracted the disease. Symptoms did not begin to show until September 24, five days after he had returned to Dallas, Texas.  Duncan was admitted to Texas Health Presbyterian Hospital four days later, and succumbed to the disease on October 8. Two health workers who had treated Duncan later tested positive for Ebola but soon recovered. Another independent case within the US occurred when a surgeon who had been treating patients in Sierra Leone contracted the disease. This patient died a short while after being treated in Nebraska. Several other cases occurred within Europe as well, specifically Germany, Norway, France, Italy, Switzerland, and the United Kingdom. Overall, the epidemic reached its peak in September 2014, with cases being reported up until April 2016.14

In May 2018, a new outbreak emerged in Congo, with 19 dead in just a matter of weeks. As of now, 39 total cases have been confirmed with around 400 people who have come in contact with the patients being monitored. WHO officials have announced that the experimental vaccine,  rVSV-ZEBOV, is going to be administered to patients. Officials hope that by targeting the outbreak early enough, an epidemic can be avoided and the disease can be eradicated quickly and efficiently.15

 

Concluding Remarks

Officials have found that targeting Ebola early and introducing better hygiene routine to high risk areas has already had a great effect on the number of outbreaks. By continuing to do research for a vaccine, scientists hope to greatly decrease the mortality rate of the virus and hopefully one day eradicate it totally.

References

  1. “Ebola.” MedlinePlus, U.S. National Library of Medicine, 14 May 2018.

  2. “Ebola (Ebola Virus Disease).” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 27 Dec. 2017.

  3. “Ebola (Ebola Virus Disease).” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 22 July 2015.

  4. “Viral Hemorrhagic Fevers.” Google Books.

  5. “Ebola Treatment Research.” National Institute of Allergy and Infectious Diseases, U.S. Department of Health and Human Services, 8 May 2018.

  6. Kadanali, Ayten, and Gul Karagoz. Advances in Pediatrics., U.S. National Library of Medicine, 2015.

  7. Pollack, Andrew. “Ebola Drug Could Save a Few Lives. But Whose?” The New York Times, The New York Times, 8 Aug. 2014.

  8. “First French Ebola Patient Leaves Hospital.” Reuters, Thomson Reuters, 4 Oct. 2014.

  9. Sissoko, Daouda, et al. “Experimental Treatment with Favipiravir for Ebola Virus Disease (the JIKI Trial): A Historically Controlled, Single-Arm Proof-of-Concept Trial in Guinea.” PLOS Medicine, Public Library of Science.

  10. Korkmaz, Ahmet, et al. “Ebola Virus Disease: Potential Use of Melatonin as a Treatment.” Freshwater Biology, Wiley/Blackwell (10.1111).

  11. Goldstein, et al. “Sierra Leone Trial to Introduce a Vaccine Against Ebola (STRIVE): Evolution of a Clinical Trial During an Ebola Outbreak | Open Forum Infectious Diseases | Oxford Academic.” OUP Academic, Oxford University Press, 24 Oct. 2016.

  12. "Ebola Virus Disease." WHO. N.p., Sept. 2014.

  13. “After Ebola in West Africa - Unpredictable Risks, Preventable Epidemics | NEJM.” New England Journal of Medicine, Oxford University Press.

  14. “Ebola: Mapping the Outbreak.” BBC News, BBC, 14 Jan. 2016.

  15. Phillips, Kristine. “Ebola Has Infected Dozens so Far in Congo, Killing 19, WHO Says.” The Washington Post, WP Company, 14 May 2018.

Last Updated: 15 May 2018.