American doctor Kent Brantly is believed to be the first Ebola patient in the U.S. when he arrived in the country earlier this month. The doctor's planned arrival has stirred controversy early on as many feel threatened of the presence of patients infected with a highly fatal virus in the country.

It appears though that this is not the first time that the U.S. had cases of Ebola. The country has already dealt with the virus 25 years ago albeit it involved a strain that is not lethal to humans.

In 1989, dozens of cynomolgus macaques that were imported from Ferlite Farms in Mindanao, Philippines, suddenly died at the primate quarantine unit of the Hazelton Research Products (HRP) in Reston, Virginia, where animals were kept before they are sold for laboratory testing.

Concerned that they might be dealing with a simian hemorrhagic fever outbreak, HRP officials contacted the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID ) in Fort Detrick, Maryland. Initial tests showed that the virus responsible for the deaths of the monkey was the Zaire strain of the Ebola virus, the most fatal strain of the virus with 90 percent fatality rate in infected humans.

Four individuals working at the quarantine facility were also found positive for exposure to the virus although these individuals did not get sick. Scientists later on learned that the virus they were dealing with is of a different strain. The Ebola-Reston strain may look similar to the Zaire strain under the microscope but it is the only one of the five forms of Ebola virus that does not pose harmful risks to humans.

Had the virus been deadly to humans, it could have a serious impact as Dr. C.J. Peters, who was involved in containing the outbreak and is now with the University of Texas Medical Branch, said that there were opportunities for trouble such as a nearby shopping center 

At the time, Ebola is believed to spread through the air so the infected monkeys were euthanized. Now, scientists are already aware that the virus spreads via direct contact with body fluids of those infected and not through the air.

"The big difference between now and 1989 is that nobody else knew what Ebola was," said Gerald Jaax, an army scientist who was among those who responded to the outbreak more than two decades ago.

Jaax, who now serves as Kansas State University's associate vice-president, said that one of the most important legacies of the Reston outbreak was that none of the dozens of workers who contained the outbreak was exposed to the virus. The plan used to keep the outbreak responders safe worked and now even provides a good blueprint for the protocols observed in bringing back the two Americans who were infected of the Ebola virus in Liberia.

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