Special Articles: Review of Infectious Disease Literature
Increase in Viral Gastroenteritis Outbreaks in Europe and Epidemic Spread of New Norovirus Variant
Editor's Note: This section of IDCP features summaries of publications relevant to the practice of HIV/AIDS. In most cases, a comment is provided from the editor concerning interpretation, impact or further relevant information on the topic reviewed. This represents a modification of selected entries in the "What's News" section of the Johns Hopkins website for ID HIV/AIDS (reprinted from www.hopkins-aids.edu with permission). John G. Bartlett, Johns Hopkins University, School of Medicine, Baltimore, MD.
Increase in Viral Gastroenteritis Outbreaks in Europe and Epidemic Spread of New Norovirus Variant Lopman B et al. Lancet. 2004;363:682
This study addressed the issue of the apparent increase in outbreaks of norovirus in hospitals in the United Kingdom and cruise ships in the United States. The study was based on results of a surveillance network of viral gastroenteritis in 10 European countries. Three regions, including England, Germany, and the Netherlands, had sustained epidemiologic and virologic data from 1995 to 2002. Outbreaks were generally identified using RT-PCR to identify norovirus. The results of the surveillance showed a striking increase in outbreaks in 2002, and this coincided with the detection of a new predominant norovirus variant of genogroup 114, a new previously unrecognized strain that had a consistent mutation in the polymerase gene. This new strain was detected in 9 of the 10 countries. During the 8-year period of review, there were 2324 laboratory-confirmed outbreaks of norovirus in this database. This includes 614 in 2002 which represented a 77% increase from the previous peak of 347 in 1995. Of 351 outbreaks in 2002, 232 (66%) involved genogroup 114. The authors postulated that this new variant was either more virulent or more environmentally stable to account for the surge in cases. The following table summarizes data for individual countries for the comparison of 2002 for the previous period of study with an indication of this change in percent.
Comment: Norovirus was identified as a cause of 85% of 3714 outbreaks of nonbacterial gastroenteritis in 10 European countries in 1995 to 2000 according to the editorial comment by Colonel Kirkwood (Lancet. 2004;363:671). This is an enteric pathogen which requires a record small inoculum of less than 10 virions. Furthermore, these strains remain viable on surfaces for weeks and possibly months, and patients continue to shed the virus long after symptoms have resolved (Rockx B et al. Clin Infect Dis. 2002;35:246). These observations presumably account for its frequency as an important cause of epidemic gastroenteritis which have been reported in nursing homes, hospitals, and cruise ships. The recent increase in outbreaks has been attributed to the appearance of a new strain which, as noted, may be more virulent or have unique properties for survival in nature.© 2004 Lippincott Williams & Wilkins, Inc.