Virus outbreak aboard cruise ship delays departure from New Orleans

Saturday, February 04, 2012

By The Times-Picayune

About 200 passengers aboard a cruise ship docked in New Orleans contracted norovirus Saturday, causing a delay in the ship's departure from the city. Norovirus can cause diarrhea, vomiting and stomach pain.

According to WDSU.com, 20 of the 200 affected passengers on the Royal Caribbean line's Voyager of the Seas were quarantined in the port as a result of their illness.

The ship's departure was delayed at least two hours Saturday evening as cleaning crews sanitized the Voyager of the Seas.

The 15-deck ship sails weeklong cruises out of New Orleans with as many as 3,100 guests on board.

Attempts to reach Royal Caribbean representatives were not successful.

Hours earlier, the Associated Press reported that more than 200 passengers aboard two Princess Cruise Lines ships headed to Miami also had contracted norovirus.

The Crown Princess was docked at Port Everglades, Fla., after a seven-day cruise during which 140 passengers and 18 crew members were affected by the virus.

Meanwhile, 81 passengers and nine crew members aboard the Ruby Princess were also reported to be affected by norovirus. That ship is scheduled to dock Sunday morning.

Does the story sound familiar?

Norovirus (formerly "Norwalk Agent") is an RNA virus (Family Caliciviridae) that is responsible for approximately 90% of epidemic nonbacterial outbreaks of gastroenteritis around the world, and may be responsible for as much as 50% of all foodborne outbreaks of gastroenteritis in the US. 

Most outbreaks or epidemics occur in places where people come together in close contact (for example, cruise ships). Norovirus infections are transmitted person to person, by contaminated food and water, and by viruses on contaminated surfaces.

History

Norovirus was probably first noticed by Dr. J. Zahorsky in 1929 and termed "winter vomiting disease." In November 1968 in Norwalk, Ohio, there was an outbreak of gastroenteritis among children at Bronson Elementary School thought to be caused by a virus. In 1972, electron microscopy on stored human stool samples identified a virus, which was given the name Norwalk virus (also termed particle or agent). It was classified as a "small round virus" and later, after genetic studies, classified as a member of the family Caliciviridae, with a single strand of RNA for its genome. The name of the genus, Norovirus, was approved in 2002.

Pathophysiology

Norovirus affects people of all ages. The virus is transmitted by contaminated food (particularly shellfish and salad ingredients) or water, by person-to-person contact, and via aerosolization of the virus and subsequent contamination of surfaces. The virus is highly contagious, with as few as one to ten virus particles being able to cause infection. Infections spread very rapidly; many norovirus outbreaks have been traced to food that was handled by one infected person. Infected individuals continue to shed the virus after symptoms have subsided, which can continue for many weeks.

When a person becomes infected, norovirus begins to multiply within the small intestine by attaching to gastrointestinal cells. After approximately one to two days, norovirus symptoms can appear. The principal symptom is acute gastroenteritis that develops between 24 and 48 hours after exposure, and lasts for 24-60 hours. The disease is usually self-limiting, and is characterized by nausea, forceful vomiting, watery diarrhea, and abdominal pain; and, in some cases, loss of taste. General lethargy, weakness, muscle aches, headache, coughs, and low-grade fever may occur. Severe illness is rare-although people are frequently treated at emergency wards, they are rarely admitted to a hospital. The number of deaths from norovirus in the US is estimated to be around 300 each year, with most of these occurring in the very young, elderly, and persons with weakened immune systems. Symptoms may become life-threatening in these groups if dehydration is ignored or not treated.

After infection, immunity to norovirus is usually incomplete and temporary. There is an inherited predisposition to infection; individuals with blood type O are more often infected, while blood types B and AB can confer partial protection against symptomatic infection.

Prevention/Treatment for Norovirus Infections

In the majority of norovirus infections, medical treatment is not required because most infections are self-limiting and resolve with no lingering problems. Oral intake of fluids is recommended for all people with norovirus infection to avoid dehydration. People with severe nausea and vomiting are often given medications to reduce or stop vomiting. Individuals who become dehydrated may require intravenous fluids with electrolytes to avoid complications of dehydration. A few severely dehydrated patients may require hospitalization.

Although research is ongoing to produce a vaccine to norovirus, currently there is none available. Further, there are many different strains of the virus, which makes vaccine development difficult. Even the body's immune defense mechanisms have difficulty producing effective immune responses to norovirus. In addition, the infection is short-lived and usually self-limiting which suggests that the body does not produce a good immune responses to this infection. Although all of the reasons are not understood in detail, it is clear that most individuals can be repeatedly infected with norovirus.

Acknowledgments

Wikipedia:http://en.wikipedia.org/wiki/Norovirus

C. P. Davis. Noroviurus Infection, in 

emedicinehealth.com: February 9, 2012

For More Information

http://www.cdc.gov/ncidod/dhqp/id_norovirusfs.html

http://emedicine.medscape.com/article/224225-overview