(Fair Use Excerpt): Nearly 300 passengers aboard the Royal Caribbean's Oasis of the Seas cruise ship were sickened with a stomach virus since it departed Port Canaveral in Brevard County, Florida, on Sunday.
The ship has been docked in Jamaica today but passengers were not permitted to disembark and the ship will be returning to Port Canaveral, where the cruise will terminate.
Norovirus (formerally known as the Norwalk virus, Norwalk-like virus, or Norwalk agent) is a member of the viral family caliciviridae. In humans, norovirus most commonly causes acute-onset nausea, vomiting and/or diarrhea, usually with abdominal pain or at least abdominal discomfort. Fever, body aches, and generalized malaise are common, as is loss of appetite. Sometimes, we see patients also exhibiting mild upper respiratory symptoms (congestion, cough, runny nose). The disease usually lasts 2-7 days before resolving. It's rarely fatal in developed countries, but it's very unpleasant. This particular virus is quite interesting to me as a physician with a graduate degree in molecular biology because of just how effective it is as a molecular parasite and also just how stubborn it is as a virion (virus particle).
The illness is often called "stomach flu" although norovirus is not related to influenza virus. I discourage the use of this misnomer and prefer "winter vomiting disease." The proper medical term is "acute gastroenteritis," or "AGE."
*The disease itself is extremely contagious. During the peak of the illness, a single gram of diarrhea or vomitus can contain a staggering one trillion virus particles. However, it takes as few as 18 particles to make someone ill. (GRAPHIC SENTENCE) Because vomiting can be forceful, microscopic droplets of vomitus containing at least 18 particles can be suspended in the air for several minutes and travel several meters, infecting individuals on the other side of a restaurant (for example).
*30% of people infected with norovirus show no symptoms but continue to shed virus for several days. Moreover, even those who do develop symptoms can shed virus for 24-48 hours prior to the illness and shedding has been reported as long as 7 days later.
*The virus particles themselves are extremely robust. They can survive on surfaces (especially when protected from sunlight) for weeks and in still water for perhaps years. They can survive heating above 60°C and most common disinfectants won't inactivate them. Basically, boiling, bleach, and incineration are the only effective ways to destroy the virus particles. Oasis's interior will need to be thoroughly wiped down with bleach.
*Immunity to norovirus after infection is incomplete with as many as 30% of patients having no detectable antibodies. In addition, when immunity develops, it is short-lived, lasting 4-7 years. The virus seems to employ a number of molecular tricks to evade immune surveillance.
*There is no specific treatment for norovirus, although two vaccine candidates (one oral and one injected) are in clinical trials. Anti-nausea meds can assist with oral hydration. I usually advise my patients to avoid artificial red dyes as these may be confused for blood in vomitus or diarrhea and trigger an unnecessary visit to an emergency room (and a lot of parental anxiety... I always say: "let's not make this any harder than it has to be"). I don't recommend anti-diarrheal medications; best to get the disease out rather than holding it in.
Hoping that those aboard Oasis stay well and have a safe trip home. I think of those flying home from Port Canaveral and really hope that none of them develop acute gastroenteritis mid-flight. That would be terrible.