The Ebola virus has shown us some viability and survivability in the recent past as the World Health Organization (WHO) reported on studies that showed that men who recovered from Ebola virus disease were reported to shed live virus in semen up to 82 days after onset of symptoms.
Now, researchers from two Pennsylvania universities and the National Institutes of Health (NIH) suggest that the procedures for disposal of Ebola-contaminated liquid waste might underestimate the virus’ ability to survive in wastewater.
In fact, researchers from the University of Pittsburgh, Drexel University, and the NIH report in a study published in the journal Environmental Science & Technology Letters say the virus can survive in detectable concentrations in wastewater for at least a week or longer.
“Initial research by the WHO and CDC recommended disposing of Ebola-contaminated liquid waste into a latrine or treatment system without disinfection because the virus wasn’t expected to persist in wastewater,” explained Kyle J. Bibby, assistant professor of civil and environmental engineering at Pitt’s Swanson School of Engineering and principal investigator of the study. However, Bibby notes, “We found that the virus persisted over a period of at least eight days.”
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. The testing was performed in a secured lab at the 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.
“These results demonstrate a greater persistence of Ebola virus in wastewater than previously speculated,” said Charles Haas, co-author; head of the Department of Civil, Architectural, and Environmental Engineering; the LD Betz Professor of Environmental Engineering; and director of the Environmental Engineering Program. “While the Ebola virus was found to be generally less persistent than enteric viruses in wastewater, the identified survival period might suggest a potential of a wastewater exposure route.”
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.
The team also notes that the virus’ seemingly early decay upon entry into wastewater might be due to the viral particles clumping together or latching onto other particles in the water, rather than the virus dying.
A proposed solution, already adopted by the WHO, would be to hold the contaminated liquid waste for a longer period of time before releasing it into the sewage system.
The West Africa Ebola Virus Disease (EVD) outbreak has resulted in more than 28,000 cases and 11,000 fatalities, according to the WHO.
