By Margaret Pizer
Viruses tend to fly—or float—under the radar when it comes to most water quality standards, but Wendi Quidort’s research may be changing that soon. The Virginia Sea Grant Graduate Research Fellow, who is working towards her Ph.D. at Virginia Institute of Marine Science (VIMS), has been making some interesting discoveries about what viruses released from wastewater treatment plants might be doing in Virginia’s creeks and estuaries.
Although the main focus of wastewater regulations is bacteria, a variety of viruses from human digestive tracts are also released by wastewater treatment plants. These viruses can cause diseases ranging from conjunctivitis to respiratory infections to classic “stomach flu.” However, many viruses in the water are difficult to detect, and the most common method of detecting them, called quantitative PCR, does not distinguish infective viruses—those that can make people sick—from those that are inactive.
To address these issues, Quidort has been studying patterns in the persistence of human adenovirus in estuarine water, as well as the infectivity of the virus, and, in a separate set of experiments, the uptake of the virus by oysters. Adenovirus is very common in wastewater treatment plant outflows, and can cause a variety of illnesses.
During three seasons of careful sampling—fall 2011, spring 2012, and summer 2012—Quidort, along with her advisors, VIMS professors Kim Reece and Howard Kator, has placed bags of adenovirus-contaminated estuarine water in a Virginia creek under a variety of conditions. They have found that adenovirus can persist in the water for more than a month. The virus breaks down more quickly in the presence of light, but even in the dark it breaks down faster in the summer than in the fall or winter. This suggests that water contamination with adenovirus may be more of an issue during the colder months, when other indicators of fecal contamination such as E. coli are often less prevalent.
In the summer, adenovirus also disappears faster in the presence of other estuarine microorganisms that in sterile estuarine water. Quidort says there are several possible explanations for this difference. It may be that the other microorganisms are consuming the virus, or that algae in the water produce chemicals that degrade the virus.
As a complement to her work in the field, Quidort is looking at oyster uptake of adenovirus in the lab. Oysters do accumulate the virus in their tissues, but she has also found that when moved to uncontaminated water, the oysters gradually eliminate the virus from their systems. This is a promising result for oyster relay, a process in which oysters are moved to clean water for a period to allow them to remove toxins and disease organisms from their systems before they are taken to market.