HARVARD GAZETTE ARCHIVES

Unique Strain of Virus Blamed for '94 Outbreak

By William J. Cromie

Gazette Staff

Those who were part of it will never forget the three days of nausea, vomiting, headaches, chills, cramps, fever, diarrhea, and muscles aches. On Dec. 6-8 1994, 188 freshmen, 10 food-service workers, and uncounted others became victims of virulent stomach and intestinal distress.

Rooms, hallways, and toilets in University Health Services were overcrowded and odoriferous. Administrators and health workers were as upset as the students' stomachs. They surveyed and inspected everything: vomit, stool, blood, water, ice, food, kitchen surfaces, and utensils.

Weeks passed before researchers from the Centers for Disease Control and Prevention (CDC) in Atlanta identified the cause as a small round virus spread by a salad chef in the freshman dining hall.

The outbreak is scientifically chronicled in the April issue of the Journal of Infectious Diseases by 12 researchers representing the CDC, the Massachusetts Department of Public Health, University Health Services (UHS), and the Harvard School of Public Health.

The report says that the virus is a hitherto unidentified strain of the Norwalk type. The name honors Norwalk, Ohio, where the mother virus was first identified as the cause of a 1968 outbreak of gastroenteritis.

The virus was first seen through an electron microscope on Dec. 20, 1994, by CDC researchers. Its genes were then isolated and sequenced by a technique similar to the DNA fingerprinting used in the O.J. Simpson and other criminal investigations.

Contaminated Salad

The outbreak originated with an infected female who prepared salads in the kitchen of the freshman dining hall. She was found to be ill on Dec. 4, 24 hours before students started getting sick.

"This type of gastroenteritis has an incubation period of 24 to 30 hours," noted David Rosenthal, director of UHS. "Retrospectively, it was probably too late to change the outcome." In other words, salad ingredients may have already been infected.

Those who handle food at the Dining Services wear rubber gloves, but that's no protection against viruses. "Gloves can carry them on the surface just as hands can," noted Michael Berry, head of Dining Services.

The woman continued to work on Dec. 5. The next day, 102 students overwhelmed the Health Services.

Why wasn't the woman sent home? Berry was asked. "There's no way you can know the state of health of every employee every minute of the day," he replied. Of course, at this time the virus had not yet been identified. Also, UHS normally sees 6 to 12 cases of such gastroenteritis a day, according to Rosenthal.

"The initial batch of illness probably came from consumption of food in the salad bar," Rosenthal said. "Those who got sick after we closed the kitchen on Dec. 6 were infected by their roommates and friends."

UHS medical records show 147 cases on Dec. 7, dropping to 32 the next day, then to 14 on Dec. 9. True to the Norwalk signature, the vomiting, diarrhea, and cramping subsided in 24 to 30 hours.

It was the end of the convulsion for students, but not for the University. It took two weeks to determine the cause was a virus and not a bacterium that contaminated spoiled food. Harvard's Environmental Health and Safety Office, working with the Cambridge Department of Sanitation, checked water and sewage systems supplying the freshman dormitories and the dining hall. The products and facilities of those who supplied food were closely checked. Freshmen filled out questionnaires about what they ate, when, and who they had contact with.

Investigators wrapped up their case when the virus found in the feces of the salad maker matched those in the stools and vomit of the students.

Berry, who leaves shortly to become a vice president of Disneyland, notes that "we had a protocol for handling such outbreaks; we put it in place, and it worked well. Knowing what I did then, I wouldn't have done anything differently."

He has made changes, however, to lessen the odds of future outbreaks. "We've terminated some suppliers since then, not because they were responsible but because of details of how they handle food," he noted.

Berry also has increased inspections, training, and awareness. "We now have nine inspections a year, two by the city, three by the Environmental Health and Safety Office, and four internally," he said. "Managers attend a training program known as 'Serve Safe.' We provide plenty of sick leave, and caution everyone not to return unless they feel well. And we emphasize rudimentary procedures such as hand washing."

"Retrospectively," he continues, "we handled the outbreak in the best way that we could have. I'm not embarrassed about anything we did."