State health officials are warning beach lovers in Waikiki about a spike in an “indicator bacteria” in the waters off Sans Souci Beach that could lead to diarrhea and vomiting.

Health Department officials aren’t sure what caused levels of the indicator bacteria called enterococci Wednesday to increase to a rate of 130 enterococci per 100 milliliters, said Myron Honda, an environmental health specialist with the department’s Clean Water Branch.

“Right now we’re not sure what caused this,” Honda said. “Normally it’s due to rainfall and surface runoff, but I’m not aware of any rain event in that area. It grows in the soil, especially around streams. Whenever it rains, all of that stuff gets washed down and ends up in the ocean.”

High levels of enterococci “would indicate sewage pathogens that would probably cause gastrointestinal distress like diarrhea, vomiting, things like that,” Honda said.

Regular weekly water samples were taken Wednesday. Test results take 24 hours, and health officials posted warning signs Thursday, Honda said.

Everyone has enterococci in their system, he said.

“It’s a normal gut bacteria,” he said. “Everybody has it in the gut.”

Sans Souci Beach, also known as Kaimana Beach, is located Diamond Head of the Waikiki Natatorium War Memorial.

In February nearby Moana Beach saw an even bigger jump: 150 enterococci per 100 milliliters, Honda said.

“The very next day it went down,” he said.

Another spike in enterococci was detected at Ko Olina earlier this year.

“Same thing,” Honda said. “It went down the next day.”

The Clean Water Branch late last year began complying with Environmental Protection Agency requirements to specifically test for enterococci, Honda said.