"It's safe to say we have ruled out food poisoning in favor of a virus," University sanitary inspector Charles Krause said yesterday, after completing his investigation of Monday's sudden outbreak of stomach illnesses.

Krause's conclusion came after four days of sampling the central kitchen's food handling processes and portions of food similar to that served Saturday and Sunday, the meals that most likely would have caused 21 people to complain of diarrhea, vomiting and severe nausea early this week.

But the manner of investigation and case-closed verdict of a virus leaves more questions unanswered than resolved. Students who complained of illness had symptoms that did not correspond with viralgastroenteritis, but rather staphylococcal food poisoning.

Krause said that analysis of a stool sample from one person hospitalized for the sickness showed no signs of staphylococcal food poisoning, a disease that appears one to six hours after ingestion of either improperly refrigerated meat or handlercontaminated milk products. But a stool sample could not reveal staph bacteria, because of the peculiar nature of the toxin.

The investigators failed to ask most of the stricken students what it was exactly they ate. "They probably wouldn't remember that far back," Krause said, but nutritionists at the School of Public Health said yesterday that this criterion was one of the first concerns sanitary inspectors must address if there is a possibility of food poisoning.

The investigators also failed to take into account that in Eliot House, where most of the cases occurred, only about one in five sickened students bothered to report their illness to UHS--a figure that would reinforce the probability that it was a form of mass staphylococcal infection, rather than simply a small virus-susceptible minority, which was affected.