Keeping a Beach Trip from Going South

Norovirus infections transmitted through swimming water investigated in Oregon lake

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) Summer is just around the corner, which means trips to the lake, fun in the sun and ... stomach bugs?

A new study investigated an outbreak that occurred in 2014 at an Oregon lake. The authors of this study are urging people to take steps to stay safe while swimming this summer.

"On July 14, Multnomah County Health Department (MCHD) was notified of 13 cases of acute gastrointestinal illness among members of three separate groups who had visited Blue Lake Regional Park over the previous weekend, July 11–13," explained the authors of this new study, led by Amy Zlot, MPH, of the MCHD in Oregon.

MCHD officials interviewed people who were at Blue Lake that weekend to identify cases and learn more. In their research, they tested stool samples from patients and found that norovirus was causing the illness.

Norovirus is a contagious illness that is spread through contact with contaminated food, water or surfaces. It can cause symptoms like diarrhea, vomiting and stomach pain.

According to Zlot and team, there were an estimated 15,400 people at the lake that weekend, 70 of whom became ill.

People who swam in the lake were 2.3 times as likely to become ill as those who visited Blue Lake but did not swim.

While the patients ranged in age from 4 to 27, most were children — the average age was 10 years old.

“Children are prime targets for norovirus and other germs that can live in lakes and swimming pools because they’re so much more likely to get the water in their mouths,” explained Michael Beach, PhD, associate director for healthy water for the Centers for Disease Control and Prevention (CDC), in a press release.

Zlot and team determined that the likely source of the outbreak was a swimmer who was sick with norovirus and vomited or had diarrhea.

“Keeping germs out of the water in the first place is key to keeping everyone healthy and helping to keep the places we swim open all summer,” Dr. Beach said.

To this point, the CDC recommended a number of steps to prevent the spread of norovirus and other illnesses in swimming spots, such as showering before getting in the water and not swallowing water from lakes or pools.

And if you have been sick, it is wise to stay out of the water. The CDC stressed the importance of not swimming if you have diarrhea or have been vomiting — this can help prevent the spread of illness to others.

The CDC also recommended getting everyone out of the water every hour for bathroom breaks.

"Check diapers, and change them in a bathroom or diaper-changing area — to keep germs away from the water," according to a CDC press release.

This study was published online May 14 in the CDC's Morbidity and Mortality Weekly Report. The Council of State and Territorial Epidemiologists and the CDC funded this research. Zlot and team disclosed no conflicts of interest.

Review Date: 
May 14, 2015
Last Updated:
May 19, 2015