Norovirus -now more important than rotavirus

Norovirus has become more important than rotavirus. This is evident based on a recent review (NEJM 2012; 367: 2126-32).

Key points:

Noroviruses are the most common cause of acute gastroenteritis requiring hospital ER evaluation in U.S. adults. It is predicted to become the most common cause of diarrhea in all age groups worldwide once rotavirus infection is controlled through vaccination.
Noroviruses are small nonenveloped single-stranded RNA viruses from the Calciviridae family. There are six major genogroups.
Exposure can occur from other individuals, contaminated food/water, and environment sources, including nosocomial.
Chronic infection is common in immunocompromised hosts, perhaps 15-20% of some immunocompromised populations. Evolution of the norovirus genome in patients infected for extended periods is relatively rapid (3.3% amino acid substitutions per year).
In normal hosts, viral shedding lasts 20-40 days; in the immunocompromised, shedding can occur for years.
Can be detected readily with RT-PCR assays.
There are no vaccines or specific viral agents available that have proven efficacy. Passive antibody therapies have been given in individual cases.
Hand-washing is crucial, especially in the hospital. In one study, 80% of hospital surfaces were contaminated with multiple norovirus strains—this study was done in a unit for children with immunodeficiencies.

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