Quarantine @ Michigan Hospital

Hand washing remains an effective method to reduce the spread of norovirus pathogens. Norovirus can be aerosolized when those stricken with the illness vomit. Surface sanitizing is recommended in areas where the norovirus may be present on surfaces.

Alcohol has been proven to be an effective sanitizer against norovirus. Quaternary ammonium can be used in conjunction with alcohol to increase the duration of the sanitizing action. In healthcare environments, the prevention of nosocomial infections involve routine and terminal cleaning. Nonflammable alcohol vapor in CO2 systems or sodium hypochlorite are frequently used to sanitize rooms occupied by patients with norovirus symptoms.

Associated foods

Norwalk gastroenteritis is transmitted by the fecal-oral route via contaminated water and foods. A CDC study of eleven outbreaks in NY State list the suspected mode of transmission as person-to-person in seven outbreaks, foodborne in two, waterborne in one, and one unknown. The source of waterborne outbreaks may include water from municipal supplies, wells, recreational lakes, swimming pools, and the often overlooked culprit: ice machines.

Shellfish and salad ingredients are the foods most often implicated in Norwalk outbreaks. Ingestion of raw or insufficiently steamed clams and oysters poses a high risk for infection with the Norwalk virus. Foods other than shellfish are contaminated by ill food handlers.

Cruise ships

Norovirus continues to be a problem on cruise ships. In 2002, there were 25 reported outbreaks, with 2,648 passengers becoming ill from the virus. [1] Outbreak investigations by the U.S. Centers for Disease Control and Prevention have shown that transmission among cruise ship passengers is almost wholly person-to-person. Cruise ship water supplies have never been implicated.

In November 2006, more than 700 passengers and crew members aboard a trans-Atlantic cruise fell ill with flu-like symptoms. The outbreak, believed to be norovirus, struck people aboard the Carnival Cruise Lines' Liberty, one of the world's largest cruise ships.

In December 2006, 384 passengers of Freedom of the Seas - the largest cruise ship in the world - contracted the norovirus. At the same time, 97 passengers and 6 [? crew members] of Sun Princess cruise ship appeared to have norovirus symptoms. Weeks earlier, 97 passengers of the same Freedom of the Seas had also contracted the virus.

 Relative frequency of disease

Only the common cold is reported more frequently than viral gastroenteritis as a cause of illness in the U.S. Although viral gastroenteritis is caused by a number of viruses, it is estimated that Norwalk viruses are responsible for about 1/3 of the cases not involving the 6-to-24-month age group. In developing countries the percentage of individuals who have developed immunity at an early age is very high. In the U.S. the percentage increases gradually with age, reaching 50% in the population over 18 years of age. Immunity, however, is not permanent and reinfection can occur. There is some evidence that blood types B and AB confer partial protection against symptomatic infection.