Researchers Find Disease-Causing Parasite, Bacteria In Northeast Iowa Waters

Apr 29, 2019

Scientists at Luther College in Decorah have found signs of disease-causing bacteria and parasites in some northeast Iowa waters. The findings could be a concern in an area known for ecotourism and water recreation.

Luther College researchers tested private drinking wells, streams and springs in Winneshiek County, looking for signs of pathogens and identifying bacteria from humans, cows, and pigs.

The team, led by Luther College biologists Jodi Enos-Berlage and Eric Baack, found some sites had levels of contaminants that could cause disease, if even a relatively small amount of water were to be ingested.

The team detected the parasite cryptosporidium at 11 of the 22 private wells they tested, albeit at low levels.

Among their 48 surface water samples, more than half tested positive for crypto, and more than 20 percent contained the Shiga toxin, which is produced by pathogenic E. coli, which can sicken people.  

"We know that rural areas often have aging septic systems and they can mean that there's human fecal matter making its way to the water, in those bacteria. We didn't expect to see it in over half of our samples, which we did." - Eric Baack, biologist, Luther College

Biology professor Jodi Enos-Berlage says the levels of pathogens were generally higher in streams and springs than in private wells, though numbers varied by site and recent rainfall amounts.

“In the surface waters, crypto dominated in terms of prevalence. And the levels range from low to high, high enough where a cup of water or so could be expected to cause disease,” Enos-Berlage said.

Biology Professor Eric Baack says the levels detected in streams and springs aren’t likely to be an issue unless visitors are directly drinking the water, or accidentally ingesting it while swimming.

“We do see people in our part of Iowa that go to a spring and fill up their water bottles and start drinking, and on some times, we are definitely seeing levels of pathogens where, if you are drinking a liter of water, you are consuming levels of pathogens that could be infective,” Baack said.

Cryptosporidium and pathogenic E. coli can both cause diarrhea, stomach cramps and vomiting. According to the Centers for Disease Control and Prevention, while some infections can be mild and symptoms generally pass in a matter of days, in some cases both infections can be life-threatening, particularly for young children, the elderly, or those with compromised immune systems.

The research team tested specifically for the strain of E. coli known to cause disease, including potentially fatal complications. This strain is different than the “indicator bacteria” that public water systems typically test for, and which was detected in thousands of private wells in a recent survey by the Environmental Working Group. This indicator bacteria is itself harmless and naturally occurring in the environment, but can signify that other potentially harmful bacteria may be present.

"We want to make sure that we give ourselves the opportunity and the permission to get in the water. Because otherwise we miss a big part of outdoor experience and love of that outdoor experience and then care of those resources." - Jodi Enos-Berlage, biologist, Luther College

Apart from pathogens, the team also tracked biological markers in surface waters and groundwater, looking for signs that could link particular pathogens to specific sources, whether that be humans or ruminants.

The researchers found only a small amount of markers in private wells. But at testing sites in Winneshiek County’s springs and streams, markers for cow and human feces were widespread.

“That was a bit of a surprise. We know that rural areas often have aging septic systems and they can mean that there’s human fecal matter making its way to the water, in those bacteria. We didn’t expect to see it in over half of our samples, which we did. But at low levels,” Baack said.

Enos-Berlage says the research findings can help visitors make decisions about recreating in northeast Iowa waters, whether that’s kayaking or fishing, or more direct contact activities like swimming.

“I was already at a point to where I’m reluctant to go in the water, or with my family, shortly after rain events, in part because I know what the E. coli levels are, which means risk is elevated.”

Recreation is a growing industry in scenic Winneshiek County, with tourism spending amounting to $30 million a year, and neighboring Allamakee County, which sees about $40 million of tourism spending annually, according to a 2016 study conducted for the Iowa Economic Development Authority.

Enos-Berlage says the results of the study shouldn’t necessarily keep people out of northeast Iowa waters altogether. Active recreation plays an important part in environmental stewardship, she says.

“We want to make sure that we give ourselves the opportunity and the permission to get in the water. Because otherwise we miss a big part of outdoor experience and love of that outdoor experience and then care of those resources.”