Charles J. Krause Jr., UHS sanitary inspector, said that while he had received a copy of O’Leary’s letter, he did not agree that the temporary employees constituted a health hazard.

And Wacker said that the temporary employees were not banned because they were considered health hazards. Rather, he said, it would be impossible to test the temporary employees—who are assigned on a day-to-day basis—because UHS did not receive test results until three days after testing.

Interhouse dining hall restrictions did not last long, and were lifted after about one week.

Wacker said he was very pleased to be able to lift the ban so quickly.

“Even the students at South House, who have been most inconvenienced, have been very good about it,” he said.

In late November, the State Department of Health laboratories identified a salad worker at the Central Kitchen as a potential Salmonella carrier. Krause said that the infected employee was removed temporarily. He also selected specimens of the salad handled by the worker to test for Salmonella.

While they identified some of the possible carriers, UHS officials never found out how Salmonella spread from the Union to Winthrop House. They suspected, however, a student carried the infection, Krause said.

While at the end of November eggs remained off the dining hall menus, at the semester’s close most student employees were allowed to return to their positions, provided that they were cleared by UHS.

“On the basis of this experience, we’re going to reinforce the usual sanitary practices,” Wacker said. “You may as well learn from something like this.”

—Staff writer Risheng Xu can be reached at xu4@fas.harvard.edu.