Roughly 200 students at Ursinus College in Pennsylvania have been sickened by a stomach bug, the cause of which remains unclear. Above, the Bakes Athletic Center at Ursinus. Montgomery County Planning Commission/Creative Commons

A stomach bug has sickened approximately 200 students at Ursinus College in Pennsylvania, sending nearly two dozen to the hospital, even as the cause of the illness remains unclear. Thursday and Friday classes and weekend activities were canceled as a result, but school officials have said that classes would resume Monday.

Students first began reporting symptoms, including vomiting and diarrhea, Tuesday night, and the school decided to close Wismer Dining Hall, its cafeteria, Wednesday, after the Montgomery County Department of Health visited the facilities and recommended several corrective actions.

Those recommendations included reviewing procedures with staff for reporting illnesses and ensuring that sick cafeteria workers did not return to work until they were symptom-free for 48 hours. It also recommended better cleaning and sanitizing of surfaces where food was prepared, along with the implementation of other food safety and illness-related procedures.

The dining hall then reopened for dinner Thursday, after the health department deemed Ursinus and its dining hall to be "in full compliance with ... the department's recommendations," the school said.

Ursinus College | StartClass

The number of students reporting illness has declined since the start of the outbreak, with fewer than 10 cases over the weekend. Students who were sickened had recovered within 12 to 24 hours, the school said, as it reassured students, parents and other members of its community that "all public spaces and common areas on our campus have been cleaned, sanitized and disinfected." It added that hand sanitizer dispensers would be installed at entrances to buildings and other "high traffic areas" over the course of the coming week.

The Montgomery County Health Department's investigation into the source of the outbreak is ongoing, and a statement posted Saturday on the school's website stated that "we cannot confirm it is foodborne nor that Wismer Dining Hall was its source of origination." As a result of the outbreak, the school began offering students free video consultations with doctors at Jefferson University Hospital, in Philadelphia, through the end of February, to "make sure that all students have as many medical care resources as possible at your fingertips."

Ursinus College is a private, four-year liberal arts college in Collegeville, Pennsylvania, about 25 miles from Philadelphia, with a student body of about 1,650.