The Virginia Department of Health is investigating after the state agency received multiple reports of gastrointestinal illnesses, including illnesses in children stemming from E. coli bacteria, among visitors to Lake Anna State Park in Spotsylvania, Virginia, during the Memorial Day holiday weekend.

The state health department told ABC News as of June 12, 20 of the reported cases stem from Shiga toxin-producing E. coli bacteria, five cases are of hemolytic uremic syndrome (HUS) cases and 10 cases remain under investigation. Those who have reported falling ill started getting sick between May 27 and June 4 and at least 9 people have reported being hospitalized. The VDH said it is awaiting additional results from lake water testing conducted by the Virginia Department of Environmental Quality on June 11.

“We hope that those hospitalized continue to recover and can return home to their families soon,” Dr. Olugbenga O. Obasanjo, the Rappahannock Health District health director, said in a statement. “This is an ongoing investigation with the health department, and we will likely continue to learn about the situation in the coming days.”

According to the VDH, those who fell ill were reported to have swam in Lake Anna or had otherwise been exposed to the 13,000 acre lake, one of the most popular lakes in Virginia. However, the health department said they have not been able to confirm whether lake exposure or a portion of the lake is causing illnesses and the agency did rule out illness caused by harmful algal bloom as current algae activity in the lake is at its typical level.

The state health agency also added that although the department doesn’t have enough information to issue a swimming advisory, it does “encourage caution when swimming” and encourages the general public to follow swimming and boating safety tips.

These include:

• Never drink untreated water.
• Shower or bathe after swimming to wash off possible germs and contaminants.
• Avoid swimming if you have any cuts or open wounds.
• Avoid swimming near storm drains along natural waters.
• Avoid swimming if you are experiencing vomiting or diarrhea.
• Avoid any water with a green film on the water and keep pets out of water with a green film, which can indicate an algal bloom with toxins.
• Avoid swimming for three days after a heavy rain. Storm water can contain germs from sewage, polluted storm water and land runoff.
• Wash hands after using the bathroom and before preparing and eating food.
• Dispose human waste properly by discharging boat sewage at marinas with a pump-out unit or dump station.

What to know about E. coli

Escherichia coli, often shortened to E. coli, is a type of bacteria commonly found in the environment, food, water, and the bodies of people and animals. According to the Centers for Disease Control and Prevention, most E. coli bacteria are harmless, but there are strains that can cause illness, and E. coli illness in children can be more severe than illness in adults.

E. coli infections can cause various symptoms and issues, such as a high fever, severe stomach cramps, bloody or watery diarrhea, vomiting, urinary tract infections, pneumonia, sepsis, and more. Children under 5, older adults over 65 and those with weakened immune systems are at a higher risk of infection.

Shiga toxin-producing E. coli or STEC, in particular, can cause hemolytic uremic syndrome or HUS, which the CDC notes can lead to kidney failure, permanent health issues, or even death.

Anyone who notices diarrhea or vomiting lasting more than two days, bloody stool or urine, a fever higher than 102°F, or signs of dehydration or HUS should seek medical care immediately. Signs of HUS, a medical emergency, include little or no urination, loss of pink color in cheeks and inside the lower eyelids, unexplained bruising or rash of tiny red spots, blood in urine, fatigue, crankiness, or decreased alertness.

E. coli illnesses are treated in a variety of ways, according to the CDC, including with increased fluid intake, anti-diarrheal medication and the use of antibiotics.