Students and staff at East Meadow's Barnum Woods Elementary School were hit with a stomach virus this week that resulted in many of them staying home Friday.
School officials did not return calls, but Nassau County health officials said they learned of the outbreak Thursday night and were working with the school.
"We are investigating, and it appears to be a viral type of illness," health department spokeswoman Mary Ellen Laurain said. "We have provided recommendations to contain and prevent further spread of the illness."
The major recommendation, Laurain said, was to "thoroughly disinfect" the school with a bleach-based cleanser.
Laurain could not provide a count of those who contracted the virus.
In an email Friday to Nassau officials, Commissioner of Health Lawrence Eisenstein estimated that "over 175 staff and students appear involved."
Eisenstein wrote that the source was unknown "but presently appears to be norovirus-like (like on a cruise ship)."
Sarah Stolberg, whose 8-year-old daughter got sick Tuesday, criticized the school's slow response to the outbreak.
"This started early in the week, but the school didn't address it until today," Stolberg, a registered nurse, said Friday.
None of the illnesses reported to date were believed to be life-threatening, officials said.