State health officials say their initial suspicions were correct: Norovirus caused an outbreak of sudden nausea, vomiting and diarrhea among Anchorage high school students last week.
The illness spread quickly and struck without much warning. In more than one instance, as students were taking standardized state tests, test-takers were overcome by vomiting, according to the Anchorage School District. Working with the school district and the municipal health department, epidemiologists with the state Department of Health and Social Services said they conducted interviews with sick students, collected stool samples and pinpointed the culprit: norovirus.
The virus causes gastrointestinal illness and is typically not life-threatening, so long as the sick person stays hydrated. The outbreak was most severe at Dimond and Service high schools but likely affected other schools and the general public, the school district said.
Of the five samples collected and sent to the state's Public Health Virology Lab in Fairbanks, all five tested positive for norovirus, DHSS spokesman Greg Wilkinson said.
Epidemiologist Brian Yablon said it is unclear precisely how many people have been affected, but the sickness spread quickly and caused many students to call in sick or be sent home from school, Yablon said.
"Just at those couple schools, easily over 200 total students. District-wide, the estimate would have to be several hundred, at least," Yablon said. "This is out there in the community, and it's not just an issue in the schools, and it's not for sure that it started in the schools."
Health workers found no evidence that a common source -- one particular sick student, for example, or something all of the sick students ate -- caused the outbreak, Yablon said. And, he said, that is not something the epidemiologists expect to find.
While the virus must be ingested to take hold, it can go airborne in the form of invisible particles during a public episode of vomiting or can be transferred from a variety of surfaces, including doorknobs or stair railings, Yablon said.
"There's a certain amount of bad luck, Yablon said. "That's no one's fault. That's just how these outbreaks happen."
The best way to prevent the spread of norovirus is for people to wash their hands with soap and warm water after using the bathroom, before eating and after touching surfaces that other people have been touching, Yablon said. Such surfaces, or areas used for food preparation, should be cleaned thoroughly, he said.
The onset of symptoms is often quick and catches people off guard. Anyone with even an inkling they are getting sick with a gastrointestinal problem should not go out in public, Yablon said.
"Don't wait for the vomit to happen. You need to stay home from school or work if you feel that illness coming on," he said. "Once you're having those symptoms, you need to ride it out at home. First of all, so you don't feel miserable in public, and second so you're not infecting other people."
More information on norovirus and its prevention is available online from the state Division of Epidemiology at epi.alaska.gov.
Reach Casey Grove at casey.grove@adn.com or 257-4589.
By CASEY GROVE