Another day, another large outbreak of norovirus.

This Saturday, the University of Michigan officially announced the presence of the stomach bug on its Ann Arbor campus grounds. The announcement was made following a formal investigation by officials from the Michigan Department of Health and Human Services. At least 100 students have come down with the telltale symptoms of vomiting and diarrhea associated with the disease and sought treatment in the past week, though the tally of victims is likely higher.

"We believe that this number does not reflect the actual extent of the illness, as students are generally following our advice to self-isolate in their rooms," Dr. Robert Winfield, the university's chief health officer, told The University Record.

Norovirus is the most common culprit of food poisoning in the United States, causing anywhere from 19 to 21 million cases of acute gastroenteritis (inflamed stomach and/or intestines) annually. according to the Centers for Disease Control and Prevention. Though typically seen as more of a nuisance than anything else, norovirus also sends upwards of 50,000 Americans to the hospital and as many as 800 to an early grave every year. Its highly contagious nature, which allows it to spread from person to person or through contaminated food and surfaces, makes fighting an outbreak particularly frustrating.

That hasn’t stopped U-M officials from doing their best to contain the virus, though. As of last Tuesday, the school implemented a rigorous virus-related cleaning procedure for all of its dining halls and residence halls and encouraged sick students to steer of contact with others until they’ve stayed symptom-free for at least 48 hours. People who become sick from norovirus often show symptoms 12 to 48 hours following infection and take anywhere from 1 to 3 days to recover fully.

The outbreak is merely the second university-related one to have been discovered this month. On February 16, officials from Ursinus College in Collegeville, Pennsylvania confirmed norovirus’ role in having sickened more than 200 students in a week’s time, with the first known case reported on February 9. Norovirus also caused an outbreak among Boston College students last December, with its likely source traced back to a nearby Chipotle. On the slightly bright side, that outbreak’s spread paled in comparison to the earlier, more infamous, outbreaks of E. coli that temporarily sent the chain restaurant’s stock prices and sales plummeting last year.

As of Sunday, the source of the U-M outbreak has not been identified.