An apparent norovirus that causes diarrhea and vomiting continued Monday to afflict a substantial portion of students enrolled in Lake Harriet Community School's lower campus.

School officials said that 63 students were absent Monday with complications of the illness that resembles what used to be called stomach flu but is not a respiratory influenza. The school enrolls kindergarten through second graders.

The number of absent students is down slightly from late last week, when almost one in five of the 390 students enrolled at the campus was missing with the symptoms.

The school's upper campus for third through eighth grade students reported about twice as many students absent as on a normal Monday. Sixteen of them, or about half of those absent, had the same symptoms that have swept through the lower campus, almost all of whom have lower campus siblings.

Health officials said they hope to know more by mid-week about the strain of norovirus affecting the school after analyzing stool samples from some of those who fell ill.