The Big Sioux River and Rapid Creek winding through
the heart of South Dakota’s two biggest cities transform into nature’s
playground during the summer months, but they are far from pristine. They are
among the nearly 70 percent of waterways on the state’s list of impaired bodies
that do not meet water-quality standards.
The Big Sioux has been on the list nearly two decades,
but until last year no one had sampled it for genes that can make the
often-harmless E. coli into a disease-causing pathogen, which sickens
around 95,000 Americans annually, according to the Centers for Disease Control.
Faculty researchers Dr. Lisa Kunza, an aquatic
ecologist, and Dr. Linda DeVeaux, a microbiologist and geneticist, both from
the South Dakota School of Mines & Technology Department of Chemistry &
Applied Biological Sciences, are searching for answers that could ultimately
improve public safety. Biomedical engineering doctoral student Kelsey Murray
has been assisting.
Their initial findings last spring caused alarm among
Sioux Falls city and county officials. Ninety-five percent of the samples
pulled from Skunk Creek and the Big Sioux, both in Sioux Falls, contained a
Shiga toxin gene that can turn E. coli into a dangerous strain. Intimin,
a gene that helps E. coli colonies embed themselves in the human gut and
thrive, was found in 100 percent of the samples.
In comparison, the presence of toxin genes in every
other state where similar experiments were conducted only reached 30 percent.
An additional $50,000 from the East Dakota Water
Development District and the City of Sioux Falls is funding SD Mines research
to help discover the magnitude of the problem and potential for super bugs to
appear.
In Rapid City, Mines researchers found disease-causing
traits from six testing sites in Rapid Creek, and research is continuing to
gain a better understanding of the problem.
Are all traits carried in the same bacterium,
suggesting an immediate health concern, or do different bacteria have different
traits, posing a future health risk? Is the primary cause related to fecal
matter washing into the water after storms or is it so embedded in the
ecosystem the problem is re-suspension?
Though answers remain elusive, the commitment to help
ensure the public’s health is not. Kunza, DeVeaux, and Murray also presented at
the South Dakota Public Health Association’s meeting in June.