LYNNWOOD — An infant and a toddler from the same day care have tested positive for E. coli, though their symptoms have been mild, the Snohomish Health District and the childcare center said.

Tests are pending on two other children from Precious Child Care and Preschool for the dangerous bacterial infection.

The day care reported the first case to the health district Aug. 1. The center at 16707 13th Ave. W. in Lynnwood has been working closely with health officials to prevent any further outbreaks.

“It didn’t originate at the day care center,” health district spokeswoman Suzanne Pate said. “This facility has cooperated at every step of the way to ensure a safe and healthy environment for the children they look after.”

E. coli symptoms include diarrhea and stomach cramping. Some people develop a more serious condition that could cause kidney failure or death. Young children and the elderly are more at risk.

Steps to prevent the illness include thorough hand washing, especially after changing diapers, handling raw meat or being around pets. It’s important to wash children’s hands as well. Other important countermeasures are adequately cooking meat and washing fruits and vegetables.

Staff at Precious Child Care notified the health district as soon as they learned that a child they look after was confirmed to have E. coli, board member Leaha Carson said. It would have helped the center to know earlier, at the first signs of illness, Carson said.

“We were not notified it was even a possibility that he was exposed until it was confirmed,” she said.

The infant who first contracted the illness outside the center later passed it on to a classmate, Carson said. This week, the center sent home three other toddlers who showed possible symptoms, though tests for one child have already come back negative.

Lab tests for the other two children are expected by early next week, Pate said.

The number of E. coli cases in Snohomish County varies greatly from year to year. The health district has reported nine cases so far in 2011. There have been as many as 47 cases in 2008 and as few as 17 in 2010.

Noah Haglund: 425-339-3465, nhaglund@heraldnet.com.