The health department is still investigating the cause of the illnesses. As many as 300 people may have attended the customer appreciation picnic at Neff's Lawn Care on July 3.
A 4-year-old female, a 14-year-old male, and a 73-year-old male have developed hemolytic uremic syndrome (HUS), a kidney disease associated with severe E. coli infections.
Of those ill, 16 have tested positive for the same E. coli strain.
The health department has also reported one case of secondary infection, likely caused by a victim passing the bacteria to her younger sister.
The health department is urging those who attended the picnic and fell ill to contact health officials at 937-225-4460.
