Two more people were diagnosed with dysentery in Taichung City following an outbreak of the disease at Beitun Elementary School six days ago.
The new cases involved the children of employees at the school's kitchen who are receiving medication for disease.
The new cases brought the total number of confirmed infections to 16 since the outbreak was reported on Thursday.
One of the patients was a student at a nearby private high school.
The Taichung City Bureau of Health has begun a comprehensive disinfection program to sterilize the entire high school in a bid to prevent the disease from spreading.
Despite repeated assurances by the Centers for Disease Control that the outbreak has been contained, parents have criticized the health agency for its alleged tardy response.
Although many parents had said they would keep their children at home, they allowed them to go to school yesterday lest their absence give rise to suspicion that they are the "patient zero" at the origin of the outbreak.
The school has refused to suspended classes, arguing that the outbreak has been contained and that students and faculty would now be safe.
Taichung Mayor Jason Hu (胡志強) ordered that all schools in the city disinfect their water supply systems and, if they had not done so already, to switch to tap water.
He also said that underground water could only be used for irrigation or cleaning and never for hand washing or drinking.