Ebola hemorrahagic fever is a 20 year old virus that, with a mortalityrate of 50% to 90%, is one of the world’s deadliest viruses. Its causativeorganism is called Ebola virus. Ebola virus is a member of filoviridae, afamily of negative-strained RNA viruses. The filoviridae family consists offive known members, Marburg, Ebola Zaire, Ebola Sudan, Ebola Reston, and EbolaTai.
Ebola virus is spread in a number of ways. An outbreak starts when aninfected animal or insect, called a vector, transmits the virus to a human.
Scientists know that monkeys are both a vector and victim of Ebola, but othervectors are unknown. The natural reservoir for the virus, or organism that isimmune to it and carries it is also unknown. A search for the reservoir willtake a long time because there are so many possibilities, since Africa is in thetropics. Another way that humans can get Ebola is by eating an infected animalor drinking the milk of an infected animal.
Ebola is spread from human to human by contact with infected blood,infected body fluids, or through sexual contact. Even after a person recoverscompletely from Ebola, it may stay in the semen for up to seven weeks. In theAfrican outbreaks it has also been transmitted by the reuse of needles becausethe health care systems are so under financed. Ebola wasn’t thought to be anairborne virus, but recent studies by the US Army Medical Research Institute ofInfectious Diseases and the CDC found that monkeys showed Ebola like symptomsafter being exposed to aerosolized Ebola. The studies also found that the virusis many times present in the respiratory systems of Ebola victims. Although the1989 outbreak in Reston, Virginia wasn’t harmful to humans, it was found thatdroplet and vomit transmission played a major role in spreading the diseasethrough the quarantine facility.
The onset of the Ebola virus is very quick. The incubation periodranges anywhere from two days to twenty-one days. After signs of the virusappear, the victim can die within days, or at the most, a week. There are afew stages after being infected with the virus. The symptoms of the first stageinclude headaches, fever, muscle pain, fatigue, chills, and loss of appetite.
The second stage consists of vomiting, diarrhea, abdominal pain, sore throat,and chest pain. The last stages are very ugly. They consist of severe clottingand hemorrhaging. The clots form throughout the body and shut of blood to manyorgans, especially the brain, liver, and spleen. These organs that don’treceive blood begin to decay. Blood leaks into tissues, fills internal cavities,and stops clotting. Blood leaks through the skin and all other openings. Theskin becomes very easily ripped and the victim can bleed profusely just by beingtouched. Then the body’s connective tissues lose their stretchiness and becomevery spongy. Hemorrhages and blood clots in the brain cause the person’s faceto become expressionless and frozen. The Ebola virus spreads to all fluids inthe body and the victim eventually dies from blood loss and shock. When thevictim dies all that is left is a decayed body filled with virus particles.
Ebola virus is diagnosed in only one way. It is diagnosed inspecialized laboratory tests on blood specimens. These tests look for Ebolaantigens, antibodies, or the isolated virus in the specimens. Since the virusis so deadly, these diagnostic tests are an extreme biohazard and are performedonly with extreme caution.
The Ebola virus is the world’s third deadliest infectious disease,behind HIV, and rabies, which has a vaccine. The only treatment that can begiven to Ebola victims is support. They are usually very dehydrated and needmanagement of fluid and electrolyte balance. Victims may sometimes require IVfeeds to replace liquids. Before shock occurs it may be helpful to replaceplasma albumin. There is currently no cure or vaccine for the Ebola virus.,although it is recorded that someone in the United Kingdom was infected withEbola Zaire and was injected with the plasma of a recovered Ebola Zaire victimand recovered fully. The opposite was also shown when recovered Ebola Restonmonkeys were infected with Ebola Zaire and died faster than monkeys infectedwith just the Ebola Zaire strain. Therefore, it is thought that plasmainjections only work on common strain victims.
The first occurrence of the Ebola virus was discovered in July of 1979near the Ebola River in Northern Zaire after a worker in a cotton factory inNzara, Sudan became very ill. Later that year a similar virus spread throughmore than 50 villages along the river in Zaire. This outbreak caused about 500deaths. Scientists from the CDC in Atlanta named the new virus Ebola, subtypeZaire. The virus that caused the outbreak in Sudan was later called Ebola Sudan.
In 1977 a child in Tandala, Zaire died of a hemorrahagic fever. In 1977another outbreak occurred in Sudan and the first case was pinpointed to the sameroom in the cotton factory that the victim in 1979 had worked in.
In 1989 another strain of Ebola was found in Reston, Virginia. Thisstrain was named Ebola Reston. This outbreak was traced to monkeys that hadbeen imported from the Philippines. The monkeys infected four humans, but thisstrain of Ebola was found only to give humans flu-like symptoms.
From January through August of 1995 there was a major outbreak in andaround Kikwit, Zaire. In this outbreak there was a mortality rate of 77%, with315 cases and 244 deaths. In May of 1995 the city was put under quarantine andtroops monitored it. On July 14, 1995 the last reported victim of Ebola wasdischarged from the hospital. Health officials waited twice the maximumincubation period and on August 24, 1995, 42 days after the last reported victimrecovered, the outbreak was declared over and the quarantine was lifted.
On December 19, 1995 a small Ebola scare in the Cote d’Ivoire/Liberiaborder region was declared over. In this small outbreak only one person wasinfected, but he survived. Mr. Jasper Chea was infected with the virus whiledissecting a dead monkey. He recovered in a local hospital. This new strain ofEbola was called Ebola Tai.
The most recent Ebola outbreak was officially declared over after twoincubation periods without any other new cases on April 23, 1996. This outbreakof the disease occurred in Gabon, Africa. This outbreak resulted in 21 deathsout of 37 cases, a 57% fatality rate.
An interesting side-note to the history of Ebola is that from 430-425 BCa deadly plague killed 300,000 in Athens. Scientists from the CDC suggest thatthis ancient plague was actually Ebola. Scientists found many similaritiesbetween this plague and the recent Sudan and Zaire outbreaks. They also foundpaintings on Greek islands near Athens that have pictures of green monkeys.
This theory is questioned by Kevin DeCock, of the London School of Hygiene andTropical Medicine because he says that “one of the main symptoms of Ebola iscopious quantities of blood, which does not feature in Thucydide’s (ancientAthenian who recorded the plague) account.”Since Ebola is still an active virus and there is no cure or vaccinethere is a lot of research being done. Most of the research focuses aroundpinpointing the reservoir organism. Two major institutions are taking up thisresearch, the WHO and the CDC. The CDC is starting this research by collectinganimals and insects to experiment with. The WHO is looking for the reservoir inCote d’Ivoire. In Cote d’Ivoire the chimpanzees get infected with Ebola everyother Autumn, but there has never been enough money to research this. The WHOis doing this research and raising money to do other research on Ebola. Thereis also research for a possible cure or vaccine.
