UPDATE | 2:28 p.m.: Eleven units and 107 patients at Atascadero State Hospital are under quarantine, officials said. There haven't been any fatalities or serious complications so far, according to Jennifer Turner with the California Department of Mental Health.
Individuals within the hospital can be on or off quarantine within a few days, Turner said, depending on the duration of symptoms.
The hospital has not yet released when the quarantine began.
During a quarantine, patients are confined to their unit and not allowed to leave until symptoms aren't present for two full days, Turner said, pending a doctor's approval.
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"Staff who work on a quarantined unit are not permitted to work on another housing unit until symptoms discontinue," she added, which halts staff cross coverage within the facility.
Other precautionary actions are taken, including ramping up janitorial services, serving meals individually rather than in a dining hall and delaying admissions that can be legally rescheduled.
Gastrointestinal illness is commonly found in institutions, cruise ships, campuses and long-term facilities, Turner added.
Parts of Atascadero State Hospital are in quarantine because of a recent increase in gastroenteritis viral illness, officials announced Friday morning.
"Certain units within the hospital have been placed on quarantine to best protect the health and safety of the patients and staff within the facility," said Jennifer Turner with the state Department of Mental Health.
The number of people affected has not yet been disclosed.
The virus, which has symptoms similar to the stomach flu, can be spread through close contact with an infected person, Turner said. Close contact, she added, includes sharing food, water or eating utensils.