During a 1995 outbreak of Ebola in Kikwit, Congo, a team of scientists studied 316 people diagnosed with the disease. For the vast majority, there was an explanation of how they contracted the disease. They had a history of very close contact with a patient and body fluids, many of them in a hospital where patients were being treated.
But for 12 people there was no clear explanation of how they had become infected, said Dr. C.J. Peters, a virologist at the University of Texas Medical Branch at Galveston. He headed the research team when he worked for the CDC.
Because there was no evidence that those 12 people had been close to an Ebola patient, the researchers said they had to consider such possibilities as droplets containing virus, airborne virus particles or the touching of a contaminated object.
“The patterns suggest that most, if not all, of the infections are due to direct contact with fluids,” Peters said. “However, I cannot exclude based on the evidence that we had, a minority might be due to small particle aerosols.”