DENVER -- Officials at the Denver Public Health Department declared the University of Denver campus safe after students reported symptoms including stomach cramps, vomiting and diarrhea this week.

Health officials said a norovirus caused the stomach flu that affected 63 of the university's more than 11,000 students. The virus is spread by direct contact with contaminated surfaces, people, food or other objects. It is non-life-threatening and symptoms generally pass within 12 to 36 hours.

Most of the affected students reported symptoms April 13 and 14. By Wednesday, April 16, the number of new cases dropped off dramatically.

Since Sunday, seven students have been admitted to Porter Adventist Hospital; all but one recently admitted student have been released. Dr. Sam Alexander, executive director of DU's Health and Counseling Center, said he is working with the Denver Health Department to monitor cases and to help track the origin.

To contain the spread of the norovirus, health officials are advising regular hand washing and cleaning with disinfectants. Health officials are also advising students, faculty and staff not to clean up after ill individuals, but to call a building supervisor or custodian. DU is deep cleaning common areas at all facilities and is providing sanitizing wipes to residence halls.

Health officials inspected Centennial Halls, the residences where many of the ill students live and eat, and found no food contamination or violations of food handling protocols. Inspectors said it is safe for students, faculty and staff to live, work and eat at DU.

DU and the Denver Health Department are distributing fliers with additional information across campus. Students are being advised to contact the Health and Counseling Center.