A local health official announced Friday that seven more cases of cryptosporidium have been detected in Lawrence.
Kay Kent, director of the Lawrence-Douglas County Health Department, said that new cases that have been detected brings the total to 22 in the city.
Cryptosporidium is a microscopic organism that is a parasite to humans. It causes diarrhea, loose or watery stool, stomach cramps, upset stomach and a slight fever.
Local health officials are working with the federal Centers for Disease Control and the Kansas Department of Health and Environment to track down the source.
Most, but not all, of the cases have been linked to swimming pools in Lawrence.
The pools at the Lawrence Aquatic Center, Kansas University, Haskell Indian Nations University and Alvamar were closed and treated for the organism last weekend.
Kent sent home letters and questionnaires Thursday to families of students at Hillcrest, Prairie Park, Quail Run and Sunflower schools.
She said the Health Department would also try to track other cases by conducting random phone surveys.