The deadly outbreak of Ebola virus disease in West Africa that began in March 2014 raised new questions about the resilience of the virus and tested scientists’ understanding of how to contain it.

The latest discovery by a group of researchers, including Drexel’s Charles Haas, the LD Betz Professor of Environmental Engineering in the College of Engineering, suggests that the procedures for disposal of Ebola-contaminated liquid waste might underestimate the virus’ ability to survive in wastewater.

Current official epidemic response procedures advise that after a period of days, Ebola-contaminated liquid can be disposed of directly into a sewage system without additional treatment.

However, new data from researchers at Drexel, the University of Pittsburgh and the National Institutes of Health indicate that Ebola can survive in detectable concentrations in wastewater for at least a week or longer.

The researchers gathered their data by observing the change in viral particle concentration in two samples, spiked with different concentrations of the virus, over an eight-day period, all in a secured lab at NIH. While the researchers observed a 99 percent decrease in concentration after the first day, the remaining viral particles were detectable for the duration of the experiment.

Historically, it was believed that the virus could only be transmitted through direct contact with bodily fluids, but there have been cases where people contracted the disease without apparently coming in contact with infected fluids.

This, the study suggests, could be an indication that large liquid droplets might be a vector for the virus — which means greater care should be taken when handling contaminated liquid waste.