“It is very likely that at least some degree of Ebola virus transmission currently occurs via infectious aerosols generated from the gastrointestinal tract, the respiratory tract, or medical procedures, although this has been difficult to definitively demonstrate or rule out, since those exposed to infectious aerosols also are most likely to be in close proximity to, and in direct contact with, an infected case,” the scientists wrote. Their peer-reviewed study was published in mBio, a journal of the American Society of Microbiology.

The study’s lead author, Michael T. Osterholm, an epidemiologist at the Center for Infectious Disease Research and Policy at the University of Minnesota, touched off a small furor and was condemned by some experts last Sept. 11 when he raised the same possibility in an op-ed piece in the New York Times as concern over the spread of the deadly disease was increasing rapidly.

Less than a month later, Thomas Eric Duncan, a Liberian infected with Ebola in his home country, died in a Dallas hospital, but not before two nurses who treated him became infected, sparking fears about how prepared U.S. hospitals were to handle the disease. Public health authorities reassured Americans they were in no danger of contracting the hemorrhagic disease from casual contact with others. Ebola is transmitted by contact with infected body fluids — mainly blood, feces and vomit — experts around the world have said. This is why health care workers and people who had contact with victims were most likely to become infected in the current epidemic, they said.