As many as 200 people have gotten sick in a norovirus outbreak at a downtown Seattle office building, health officials reported Monday.
Illness at the Russell Investments Center grew exponentially after a catered event in the building, but several cases were reported before the event last Tuesday, according to Public Health-Seattle & King County, which is still investigating the outbreak that began last week.
Between 175 and 200 cases have been reported to the health department either independently or through a survey of people who went to the catered event in the building.
Nearly 200 people out of roughly 600 people who attended the party catered by California-based Bon Appetit Management Co on Tuesday reported some level of sickness, said Dr. Meagan Kay, medical epidemiologist for communicable diseases with the Seattle and King County Public Health Department.
"The source of this illness remains unclear, and we are as eager as anyone to learn precisely how and when it began," the catering company said. "We have worked with our food safety experts to disinfect the surfaces in our facility and have taken all other necessary steps to ensure food safety."
Two people have been hospitalized overnight and eight people visited an emergency room for their illness, though the conditions of the patients were not known, Kay said.
"We anticipate that number is probably low," said Kay.
Norovirus is very common, and more than a dozen outbreaks are confirmed or probable in the county each year, Kay said. "This time of year, norovirus can spread person-to-person very quickly," she said.
The Seattle building was thoroughly cleaned over the weekend, and all food service in the building has been shut down by the health department.
The virus causes the stomach or intestines or both to become inflamed with acute gastroenteritis which leads to stomach pain, nausea and diarrhea, according to the Centers for Disease Control and Prevention (CDCP).
It is the most common cause of foodborne-disease outbreaks and acute gastroenteritis in the United States, causing some 19 million to 21 million illnesses and 570-800 deaths annually, according to the CDCP.
"Door knobs, handrails, all of those things can easily get contaminated," Kay said. "It may be it is something that's still out there."
Health officials warned that people can continue to spread norovirus for weeks after symptoms are over so they should continue to be careful about handwashing and sanitation.