Airborne transmission of Ebola not studied
Despite fear that the Ebola virus will rapidly mutate into an airborne pathogen, that possibility is low, scientists say.
In August, researchers in West Africa, Europe and the United States sequenced the genomes of Ebola virus isolated from dozens of patients and found it acquired mutations as it spread. They did not test whether those genetic changes affect its ability to infect and survive.
“It's an extremely difficult thing to speculate about,” said Charles Bailey, executive director of the National Center of Biodefense and Infectious Diseases at George Mason University, who was not involved in the study. “Is a mutation capable of making it airborne transmissible? Nobody knows.”
Bailey said that while he was at the Army Medical Research Institute of Infectious Diseases, a weaker strain of Ebola infected a small colony of research monkeys. Concentrated aerosols of Ebola have shown the ability to infect, he said, but it's not known whether a sneeze or a cough can do the same.
“That experiment hasn't been done yet,” said Bailey. “If there was no concern about aerosol transmission, then why are people wearing masks? There's no absolutes.”
Ebola is an RNA virus that can infect several kinds of cells, said Kelly Stefano Cole, associate professor of immunology at the University of Pittsburgh. Its affinity for cells that make up blood vessels leads to one of the infection's most gruesome manifestations — victims bleed from their eyes, mouths and other orifices.
The virus infects cells by attaching itself to proteins on the surface of the cell. The cell swallows the virus, and once inside, through mechanisms that scientists use as drug targets, the virus makes copies of itself. Eventually, the cell bursts, releasing the virus, which moves to the next cell.
Concern that Ebola could be transmitted in the air could stem in part from the use of hazmat suits by workers treating potentially infected patients, experts said. The suits can send a confusing message about how the virus is spread, said Dr. Susan McLellan of the School of Public Health and Tropical Medicine at Tulane University.
“If you want to reduce the risk of dying a horrible death, put on your bike helmet, wear your seat belt, stop smoking and get all the guns out of your house,” she said.
Ebola is spread through bodily fluids that find their way inside the mouths and noses of healthy people, according to the federal Centers for Disease Control and Prevention.
The risk of infection is low in developed countries that have running water and clean hospitals, McClellan said.
“We have lots of 409,” she said, referring to the Formula 409 home cleaning product. “Bleach is going to be readily available. We can wash our hands.”
There is no cure for Ebola and no commercially available treatment. Five known patients who were treated in the United States received experimental medications. The drugs included an antiviral that showed some ability to kill Ebola in test tubes, and one made in tobacco plants that combines three genetically engineered antibodies.
Megha Satyanarayana is a Trib Total Media staff writer.