NH DHHS Issues Public Health Advisory for Swimmers at Silver Lake State Park

Concord, NH – The New Hampshire Department of Health and Human Services (DHHS) Division of Public Health Services (DPHS) is advising swimmers at Silver Lake State Park in Hollis, NH, of possible contamination of the lake water with Shigella bacteria. DPHS has received reports of five people who became ill with a gastrointestinal illness after swimming at the lake. Four of these people were confirmed to be infected with the Shigella bacteria.All five people were sick in July and have recovered.


Preliminary results from a water sample taken at Silver Lake on July 27, 2009 tested at the DHHS Public Health Lab suggest the lake water may contain Shigella bacteria, but further investigation is ongoing. DHHS and the Department of Environmental Services (DES) have taken a proactive approach to protect the health of the public by issuing an advisory at the Silver Lake State Park. DHHS and DES are continuing to sample and analyze water collected at the public beach. A series of E. coli samples, an indicator organism of sewage contamination, analyzed by DES did not measure levels above the State Standards for Designated Public Beaches.


“Shigella is a bacteria that causes diarrheal illness in humans and is most commonly spread from person to person, although consuming contaminated food or water can also cause illness,” said Dr. José Montero, Director of Public Health at DHHS. “Though it has not been confirmed yet that this lake is the cause of this outbreak, if you have been swimming in Silver Lake in Hollis, NH, you should be on alert for possible symptoms of Shigella. Typically, washing your hands before eating any food is the best way to prevent Shigella infection.”


Symptoms of Shigella illness include diarrhea, fever, and stomach cramps starting a day or two after being exposed to the bacteria. The diarrhea is often bloody. Shigella symptoms usually resolve in 5 to 7 days. People who have been swimming at this lake and are experiencing the above symptoms should seek medical attention and have their stool tested for Shigella.


Healthy swimming behaviors will help protect people from recreational water illnesses (RWIs) and help stop germs from getting into the water.


Healthy swimming behaviors include the following:

Don’t swim when you have diarrhea. You can spread germs in the water and make other people sick.

Don’t swallow the water. Avoid getting water in your mouth.

Practice good hygiene. Shower with soap before swimming and wash your hands after using the toilet. Germs on your body end up in the water.

Take children on bathroom breaks or check diapers often. Waiting to hear, "I have to go" from young children may mean that it's too late. Change diapers in a bathroom or a diaper-changing area and not on the beach or at the poolside. Germs can spread in and around the water. Wash your hands after changing diapers. Wash your child thoroughly (especially the rear end) with soap and water before swimming. Invisible amounts of fecal matter can end upin the water.


For more information about Shigella or other recreational water illnesses, visit the DHHS website at www.dhhs.nh.gov or the Centers for Disease Control and Prevention website at www.cdc.gov or call the New Hampshire Communicable Disease Control and Surveillance Section at 603-271-4496.