Four cases of mumps have been confirmed on Harvard’s campus, according to Harvard University Health Services Director Paul J. Barreira, marking the return of active cases of the contagious disease that swept across campus in the spring.

In the spring, a mumps outbreak ultimately resulted in 66 active cases on campus, and the University quarantined some students to try and prevent the spread of disease. No active cases of the disease were on campus in September.

It is unclear whether the new cases are connected to the previous outbreak, which began in February. HUHS is collaborating with local and state public health officials to “track and monitor the situation,” according to Barreira.

“At this time, public health officials are still investigating the origins of these cases to determine whether they are officially connected to the other cases at Harvard or are isolated incidents,” Barreira wrote in an email to Harvard affiliates.

As Harvard prepares for thousands of Yale students to come to Cambridge for this weekend’s annual Harvard-Yale football game, Barreira said he and HUHS are working to contain the disease. In his email, Barreira urged any individuals experiencing mumps symptoms of the disease to “refrain from public activities, avoid travel and public transportation, and contact Harvard University Health Services.”

The outbreak began in February, when HUHS confirmed the first two infections on Harvard’s campus. Mumps cases steadily rose throughout the semester, and there were 58 active cases at the end of the 2015-2016 academic year.

Harvard and Mass. state health officials said earlier this year that they thought the decline in infection over the summer was due to students’ departures from Harvard for the summer.

Barreira wrote in a separate email Thursday evening that HUHS “is actively working with groups from across the University to keep the Harvard community informed about best practices for preventing the spread of mumps.”

On Wednesday, the Boston Globe reported that Tufts University identified nine additional cases of the disease in the past three weeks. Tufts and Boston University also had mumps outbreaks in the spring.

—Staff writer Kenton K. Shimozaki can be reached at kenton.shimozaki@thecrimson.com. Follow him on Twitter @KentonShimozaki.