Health department still investigating waterborne parasite

August 10, 2018

After announcing an investigation into a waterborne parasite last Thursday, the Minnesota Department of Health hadn’t pinpointed an outbreak of cryptosporidiosis at Zumbrota campgrounds.

They are limited by the difficulty of investigating recreational waterborne diseases, according to Trisha Robinson, an epidemiologist and waterborne diseases unit supervisor.

“Water testing in general has a lot of limits to it,” Robinson said. “If we take a sample from one area and it’s clear, sometimes three feet over it may not be.”

What the MDH has done, instead, is try to assess the types of activities done by people who reported getting sick. The idea is to determine where the exposures may have taken place.

Cryptosporidiosis is a diarrheal disease caused by a parasite called cryptosporidium.

The parasite spreads through contact with fecal matter from infected people or areas. It is the most common cause of waterborne illness in the U.S.

The MDH has determined that some people who became sick after visiting the Zumbro camp areas had not gone into the river. They probably won’t ever determine where the first exposure took place.

“When you’re in a place where you have multiple bodies of water, it’s hard to tell,” Robinson said.

Eliminating a waterborne parasite outbreak is also tough, said Steven Diaz, the assistant division director for the Department of Environmental Health, said.

A pool, he said, could be hyperchlorinated to kill the resistant, long-lasting cryptosporidium. But with natural bodies of water, the MDH just has to wait and depend on time and dilution to carry away the danger.

In the end, the only solution has been to inform people around the Zumbro camp areas so they can make their own risk decisions, Diaz said.

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