The Marburg virus was first identified in laboratory workers in Marburg, Germany, and Belgrade, Yugoslavia, in 1967. The researchers contracted the disease from African green monkeys that had been imported from Uganda. Twenty-five cases resulted from direct contact with monkeys (primary cases) and six cases resulted from others' contact with primary cases (secondary cases) in the first outbreak. Seven people died. Since then, there have been sporadic outbreaks in Zimbabwe, South Africa, and Kenya.
The symptoms and course of the disease are very similar to Ebola, although the fatality rate is lower, at approximately 25 percent.
Researchers who study these diseases do so under very strict safety conditions. In fact, there are only a couple of laboratories in the United States that have facilities that are set up to do work on such dangerous and highly contagious organisms.