The leading cause of foodborne disease is making its mark this winter. Just this February, Norovirus caused more than 200 attendees at a cheerleader camp in Washington State to become ill. In St. Maarten, a cruise ship returned to port as 31 became ill. In Virginia, an elementary school was closed because so many students were ill. And in New Jersey, more than 400 college students become ill at three universities located in the same county.
There are some important reasons that lead to so many people becoming ill from Norovirus. One is the virus’s low infectious dose. It is estimated that it may take only 10 viral particles to make someone ill. Then, there is the ability of the virus to survive for up to two weeks on dry surfaces and in water for months. The virus can be spread through a number of ways including through contaminated food or water, from contaminated surfaces, directly from a sick person, or from the intake of aerosolized droplets of vomitus.
The main symptom of Norovirus infection is another factor for its spread – acute-onset vomiting. This prevents people from becoming sick in a secure location. Rather, rapid onset can occur at a dinner table, on a carpet, or on the bus. People usually become ill within 24 hours of exposure, although longer incubation periods do occur. Once someone is sick, they can experience symptoms for 24 to 72 hours, and can remain contagious for up to 3 days.
Because of this short incubation time, low infectious dose, and ease of spread, one can see why it spreads through a school or a cruise ship so quickly. While rarely fatal, people who become ill need to watch so that they do not become dehydrated.
The most important key in preventing infection is frequent, but correct hand washing – scrubbing hands with soap and warm water. Additionally, it is important for people to stay home when ill, especially when they may have been exposed to someone who has had the illness. They should also stay home for at least 48 hours after systems have subsided. Contaminated surfaces must be cleaned using a strong chlorine bleach solution, 1 cup of bleach o one gallon of water. Cooking will destroy the organism.
CDC link for additional information