Norovirus infection can make for a miserable cruise. According to the Centers for Disease Control and Prevention (CDC) web site, this gastrointestinal virus causes acute gastroenteritis, which is also called stomach flu or food poisoning.
Noroviruses are not related to influenza viruses, which cause ordinary flu, but the name stomach flu is common. The symptoms are vomiting and diarrhea, which usually last for one to two days.
Infected individuals are contagious from the moment they feel ill until as long as two weeks after recovery. The virus can be transmitted by touching contaminated surfaces, from consuming food or drinks containing virus particles, or by direct contact with an infected person.
The online publication Cruise Critic provides information on norovirus outbreaks on cruise ships. Cruise lines are required to report all cases to the CDC, and to create a special report when the virus sickens more than 2 percent of a ship's population.
Some notable outbreaks include the following:
1. February 4, 2012. The Crown Princess reported 394 cases, and the Ruby Princess 105 cases. Both ships received special cleanings in their home port of Fort Lauderdale, Florida, delaying their departure for their next scheduled cruises.
2. March 18, 2010. The Celebrity Mercury returned home a day early after 369 passengers (20 percent of the total) reported gastrointestinal symptoms.
3. December 30, 2010. The Queen Mary 2 of Cunard reported 167 sick passengers and 28 sick crew members. Crew members began dishing out food at the buffets, in addition to extensive sanitizing procedures.
Norovirus outbreaks can happen anywhere, not just on cruise ships. Everardo Vega and colleagues at the CDC provided a review of the surveillance network called CaliciNet.
Caliciviridae is the name of the family of viruses that include norovirus. CaliciNet was started in March 2009. In the first year, 552 outbreaks were reported.
“Noroviruses are the primary cause of epidemic viral gastroenteritis and the leading cause of foodborne outbreaks in the United States,” Vega explained. Outbreaks occur year-round, but are most common in the winter months.