This is part one of three-part article on Norovirus.

Norovirus, aka the stomach bug, hospitalizes up to 71,000 and kills nearly 700 people in the United States annually — mostly children and elderly, who are more susceptible to severe dehydration and malnutrition. The virus causes gastroenteritis, which is inflammation of the stomach and intestines and leads to diarrhea, vomiting and stomach pain.

The microscopic parasite can be transmitted via aerosolization of the virus through vomit or feces, through person-to-person contact, by touching a contaminated surface and then touching the mouth, or by contaminated food or water. From November to April, when people spend more time indoors with less natural ventilation, the virus can run rampant, especially in schools and daycares.

Considering that a person sheds billions of Norovirus particles in his or her vomit or stool and it only takes fewer than a hundred particles to infect a new host, it’s easy to see why Norovirus can be such a threat. According to the U.S. Centers for Disease Control and Prevention (CDC), 61 percent of diarrhea or vomiting outbreaks are spread by direct contact with an infected person or contaminated surface. So, everyday activities in school, like playing tag during recess or drinking from the water fountain could lead to the spread of Norovirus.

To help curb the risks, distributors should be able explain the risks of Norovirus to their clients and instruct how to prevent its spread.

“Every school should see their distributor as a partner, not just a supplier,” says Mark Bishop, a consultant for the Healthy Schools Campaign, Chicago. “Distributors can play a really important role in helping schools receive the training they so desperately need to keep the school clean, safe and healthy.”