SAN FRANCISCO (Reuters) ? A Jesuit high school in San Francisco was closed for the rest of the week on Wednesday after about 300 students and 30 faculty were stricken by a stomach ailment marked by nausea and vomiting, officials there said.

The outbreak at Saint Ignatius College Preparatory school, initially believed to have been caused by a virus, sent a handful of the sickened students to hospital emergency rooms for treatment of dehydration, principal Patrick Ruff said.

He said he did not know if any were admitted.

“A large percentage of students and about 30 faculty are sick, and we thought it would be best to close on Thursday and Friday,” Ruff told Reuters, adding that about 50 students called in sick on Wednesday and more than 100 left during day.

But school spokesman Paul Totah said roughly 300 pupils in all, out of the school’s 1,360-member student body, were believed to have been affected in some way.

Extra maintenance staff were brought in to scour the entire school with a bleach-based solution, and the process will be repeated on Thursday, Ruff said.

The school consulted with San Francisco health inspectors, who visited the school Wednesday and ruled out cafeteria food or waterborne sources for the outbreak, he said.

For now health officials were describing the malady generally as viral gastroenteritis, often called stomach flu even though the illness is not related to influenza. But further testing is needed to determine whether norovirus, a common cause of gastroenteritis, was the culprit, they said.

Dr. Tomas Aragon, San Francisco’s chief medical officer, said the outbreak may have originated from a single infected student who got sick in an often-used doorway.

“A student vomited on central doors, on the rods that open these big doors. Then the bell rang and a lot of students went through that door.”

Aragon said the norovirus can survive on surfaces for days and is highly contagious.

In a message to parents updated Wednesday afternoon on the school’s website, officials said students should stay home at least 72 hours after symptoms have subsided.

(Editing by Steve Gorman and Greg McCune)

Source: http://us.rd.yahoo.com/dailynews/rss/education/*http%3A//news.yahoo.com/s/nm/20120202/us_nm/us_school_illness_california

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