Ebola virus disease (or Ebola hemorrhagic fever) was first found to infect humans in 1976. Because the deadly disease was discovered relatively recently, there is no cure or vaccine for Ebola, and treatment options are limited.
Ebola is considered by the U.S. Centers for Disease Control (CDC) to be a highly infectious disease, yet not particularly contagious. The Ebola virus is infectious because exposure to a very small amount of it — perhaps as little as one virus particle — can cause a fatal infection. Ebola is not highly contagious because it spreads only by direct contact with secretions (blood, vomit, diarrhea) from a person or animal who has the disease.
Read on for a timeline of the Ebola virus, from the first epidemic to 2014. (Note that the Democratic Republic of the Congo and the Republic of Congo are two separate countries.)
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1976: The first recognition of the Ebola virus occurs in Zaire (now called the Democratic Republic of the Congo), resulting in 318 human cases and 280 deaths. Ebola got its name from the Ebola River, which was at the epicenter of the first epidemic.
Almost simultaneously, an outbreak of a different strain of Ebola occurred in Sudan (now called South Sudan), resulting in 284 cases and 151 deaths. In Sudan, many of the infected were healthcare workers.
In England, one person in a medical laboratory was infected after an accident with a contaminated needle; the patient survived.
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1979: An outbreak of Ebola occurred in Sudan (now called South Sudan), resulting in 34 cases and 22 deaths.
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1989: In a laboratory in Reston, VA (a suburb of Washington DC), macaque monkeys arrived from the Philippines for medical testing and were found to be infected with a new strain of Ebola (later named the Ebola-Reston virus*). No humans were infected, but the story led to the 1995 bestselling book, The Hot Zone, by Richard Preston.
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1990: Ebola-Reston virus was discovered in laboratories in Virginia and Texas in monkeys imported from the Philippines. Four humans tested positive for Ebola antibodies but none got sick.*
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1989-1990: Macaques died en mass at a primate facility that exports animals to the United States. Three workers in the facility tested positive for Ebola antibodies but none got sick.*
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1992: Monkeys in a lab in Italy tested positive for Ebola-Reston virus. The monkeys came from the same Philippine export facility that was involved in the previous cases in the United States. No humans were infected.
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1994: 52 people became sick and 31 died in gold mining camps in Gabon. The cause was originally thought to be yellow fever but was later identified as Ebola.
A scientist contracted Ebola after conducting an autopsy on a chimpanzee in Ivory Coast. He was airlifted to Switzerland, where he recovered.
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1995: An outbreak occurred in the Democratic Republic of the Congo (formerly Zaire), resulting in 315 cases and 250 deaths. The epidemic swept through hospitals and families.
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1996: A small outbreak occurred in Gabon, resulting in 37 cases and 21 deaths, when a dead chimpanzee was discovered and eaten. 19 of the people involved in the butchering of the chimp became ill; the other cases were family members.
A few months later, again in Gabon, another 60 cases resulted in 45 deaths. The source of the second wave of Ebola was also traced to the finding of a dead chimpanzee.
A medical professional treating the Gabon cases became infected and was airlifted to South Africa. He recovered, but a nurse who treated him became ill and died.
Infected monkeys were again discovered in Texas and the Philippines.
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2000-2001: An Ebola outbreak in Uganda led to 425 cases and 224 deaths. This outbreak made it known that some African funeral practices can spread Ebola from the dead to the living.
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2001-2002: An outbreak occurred at the border of Gabon and the Republic of Congo, which results in 122 cases and 96 deaths.
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2002-2003: An outbreak occurred in the Republic of Congo, resulting in 143 cases and 128 deaths. Shortly after the epidemic in the same country, another 35 cases and 29 deaths were identified as from Ebola.
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2004: An outbreak occurred in Sudan (now called South Sudan), resulting in 17 cases and 7 deaths. Sudan suffered an outbreak of measles simultaneously, which at first led to several cases of misidentification.
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2007: An outbreak in the Democratic Republic of the Congo resulted in 264 cases and 187 deaths.
An outbreak in Uganda resulted in 149 cases and 37 deaths and was identified as a new strain (the fourth) of the Ebola virus.
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2008: The first known instances of pigs having Ebola-Reston are discovered at a farm in the Philippines. Six workers from the pig farm tested positive for Ebola, but none became ill.*
An outbreak occurred in the Democratic Republic of the Congo, resulting in 32 cases and 15 deaths.
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2011: One person in Uganda died of Ebola.
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2012: Two outbreaks occurred in Uganda just months apart, resulting in 17 cases and 7 deaths.
An outbreak occurred in the Democratic Republic of the Congo, resulting in 36 cases and 13 deaths.
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2014: The largest outbreak of Ebola on record occurred in Guinea, Liberia, Sierra Leone, and Nigeria, resulting in 1528 cases and 844 deaths as of August, 2014. Two American doctors in Liberia contracted the virus and were airlifted to Atlanta, GA, where they recovered.
An unrelated outbreak occurred in the Democratic Republic of the Congo, resulting in at least 2 deaths.
Both of the 2014 epidemics are ongoing.
*The Ebola-Reston virus has since been discovered to be the only one of the five strains of Ebola that is not contagious to humans.