BREMERTON — Horseshoe Lake County Park remains closed and will remain closed at least through July 18 as the investigation of multiple reports of a norovirus-type illness continues.

The Kitsap Public Health District and Kitsap County Department of Parks and Recreation temporarily closed Horseshoe Lake County Park on  July 14 and have been investigating multiple reports of a norovirus-type illness outbreak. The purpose of this release is to provide an update on the investigation.

The situation appears to be stabilized and no additional sample results will be available until early Friday afternoon at the earliest.

As of 4 p.m. on July 15, the Health District has received more than 200 reports of people getting ill after swimming at Horseshoe Lake County Park between July 10 and July 13. Based on interviews with affected people, the main symptoms being reporting are vomiting, diarrhea, and stomach cramps.

The onset of the illness is approximately four to 24 hours after swimming at the park, and the duration of the illness is approximately eight to 36 hours after the first signs of illness begin. Not all people who swam at the park during this period have become ill, and most of the people who were there have recovered.

The county park still appears to be the only affected area on Horseshoe Lake at this time. According to Kitsap County Parks and Recreation estimates, approximately 2,500 people visit the park each day during hot weather like last week.

At this point, bacteria do not appear to be the source of the illnesses.  Lake water samples for E coli bacteria that were collected on Monday morning were well below health threat levels – counts were at 9 coliform units per 100 mL and the closure standard is 126 coliform units per 100 mL. Drinking water samples from the park were also within acceptable levels and came up negative for the presence of bacteria. Based on reported symptoms and onset/duration of illness, the Health District still believes that a virus is the likely source of the illnesses.

Although there have been several reports that the toilets and showers in the restrooms were in poor condition on Saturday and Sunday with the number of people at the park, an inspection of the restrooms and septic system on Monday and Tuesday (today) showed that the facilities were in good working order. Based on interviews with affected people and the location and functional status of the septic system, it is not believed at this time that the septic system was a source of the illnesses, but the restrooms may have contributed to spreading the illness if they were overwhelmed by the amount of usage.

Stool samples have been collected from two of the ill people and have been sent to the state health laboratory for bacteria and virus analyses. Test results will not be available until Friday afternoon at the earliest. It is hoped that the stool analysis will identify the virus responsible for the illnesses.

With the help of the Centers for Disease Control in Atlanta, Georgia, the Health District will be collecting additional water samples from the park’s swimming area to be analyzed for viruses at the federal CDC laboratory. Although isolating viruses in environmental waters is extremely difficult and often unsuccessful, the attempt is being made in order to try and identify the specific virus responsible for the illnesses.

These test results also will not be available until Friday afternoon at the earliest.

The Health District has also issued an alert to all area health clinics, hospitals, labs, tribes and emergency services so they are aware of the situation.

If they have not done so already, people who visited Horseshoe Lake County Park between July 10 and July 13 who have become ill with diarrhea, vomiting, and/or stomach cramps are asked to call the Health District at 360-337-5623 to report their illness, the number of people affected, and which day(s) they were at the park.

People may also report their illness symptoms online at kitsappublichealth.org/about/health-concern.php.

If symptoms appear severe or do not improve within 24 hours, people should visit their primary care provider as soon as possible. In most instances symptoms will improve one to two days after onset.

The public is reminded that people who are ill or in diapers should not go swimming or into the water to prevent the spread of disease causing organisms.