1293. The Roles of Norovirus and Clostridium difficile among Gastroenteritis Deaths in the United States, 19992007
Session: Poster Abstract Session: Viral Epidemiology
Saturday, October 22, 2011
Room: Poster Hall B1
Background: Globally, diarrhea is recognized as an important contributor to mortality among children, but diarrheal deaths among adults have been poorly described. Clostridium difficile has emerged as an important cause of diarrheal deaths in the elderly and anecdotal evidence suggests norovirus may also contribute, although population-based data are limited. We described trends in gastroenteritis deaths across all ages in the United States and estimated the contribution of norovirus and C. difficile.

Methods: Gastroenteritis-associated deaths in the United States during 1999–2007 were identified from the National Center for Health Statistics multiple cause-of-death mortality data. All deaths in which the underlying cause or any of the contributing causes listed gastroenteritis were included. Time-series regression models were used to identify cause-unspecified gastroenteritis deaths that were likely due to specific causes; model residuals were analyzed to estimate norovirus-associated deaths. Coded and modeled deaths were summed and population-based rates were calculated using census data.

Results: Gastroenteritis contributed to an average of 11,255 deaths per year (39/1,000,000 person-years), of which 5556 (49%) were cause-unspecified. The highest all-cause gastroenteritis mortality rates were observed among persons aged ≥65 years (258/1,000,000 person-years). On average, norovirus was estimated to cause 797 deaths per year (3/1,000,000 person-years) while C. difficile caused an estimated 7,385 deaths per year (25/1,000,000 person-years). Norovirus deaths peaked during December–February, while C. difficile deaths were most frequent during March–May. C. difficile mortality increased 5-fold from 9/1,000,000 person-years in 1999-00 to 45/1,000,000 person-years in 2006-07. Norovirus mortality rates surged by up to 50% during epidemic seasons associated with emergent viral strains.

Conclusion: While C. difficile is recognized as an important cause of diarrheal death in the elderly, norovirus is likely the second leading infectious cause. The disease burden and distinct seasonal patterns associated with these pathogens should help guide appropriate clinical management strategies and vaccine development.

Subject Category: V. Virology including clinical and basic studies of viral infections, including hepatitis

Aron J. Hall, DVM, MSPH, Aaron T. Curns, MPH, L. Clifford McDonald, MD, Umesh D. Parashar, MBBS, MPH and Ben A. Lopman, MSc, PhD, CDC, Atlanta, GA


A. J. Hall, None

A. T. Curns, None

L. C. McDonald, None

U. D. Parashar, None

B. A. Lopman, None

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