Norovirus May Cause 20% of Acute Gastroenteritis Worldwide‏

Laurie Barclay, MD

July 01, 2014

Norovirus is associated with nearly one fifth of all cases of acute gastroenteritis worldwide‏, suggesting the need for vaccines or other targeted interventions to reduce norovirus burden, according to a systematic review and meta-analysis published online June 27 in Lancet Infectious Diseases.

"Despite substantial decreases in recent decades, acute gastroenteritis (diarrhoea and vomiting) causes the second greatest burden of all infectious diseases, estimated at 89.5 million disability-adjusted life-years...and 1.45 million deaths worldwide every year," write Sharia M. Ahmed, from the Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, and colleagues.

"Noroviruses are a leading cause of sporadic cases and outbreaks of acute gastroenteritis across all age groups. We aimed to assess the role of norovirus as a cause of endemic acute gastroenteritis worldwide."

The researchers included 175 studies that used polymerase chain reaction testing to assess norovirus prevalence in patients with acute gastroenteritis. They included studies done continuously for at least 1 year in a specified geographical area or population group. Among 187,336 patients with acute gastroenteritis, the pooled prevalence of norovirus was 18% (95% confidence interval [CI], 17% - 20%), as determined by fitting linear mixed effect meta-regression models. Compared with inpatient settings, in which norovirus prevalence was 17% (95% CI, 15% - 19%), there was a trend toward higher prevalence in community settings (24%; 95% CI, 18% - 30%) and outpatient settings (20%; 95% CI, 16% - 24%), but the difference was not statistically significant (P = .066).

Prevalence was also higher in low-mortality developing (19%; 95% CI, 16% - 22%) and developed (20%; 95% CI, 17% - 22%) countries than in high-mortality developing countries (14%; 95% CI, 11% - 16%; P = .058). Patient age did not appear to affect norovirus prevalence, nor did surveillance occurring during years of novel strain emergence.

"Norovirus is a key gastroenteritis pathogen associated with almost a fifth of all cases of acute gastroenteritis, and targeted intervention to reduce norovirus burden, such as vaccines, should be considered," the study authors write.

In an accompanying comment, Ulrich Desselberger, MD, from the Department of Medicine, and Ian Goodfellow, PhD, from the Department of Pathology, University of Cambridge, Addenbrooke's Hospital, United Kingdom, note that this is the largest analysis of norovirus infection and disease to date.

They point out study limitations, including uneven geographical representation of data and likely underestimation of prevalence because of lack of capture of cases associated only with vomiting.

"The inability to propagate human norovirus in cell culture has substantially hindered the identification of neutralising antibody epitopes, although these restrictions have been partly overcome," the editorialists conclude. "Thus, the development of a universal, probably multivalent norovirus vaccine might be well within reach. This development makes research on norovirus biology, virus–host associations, epidemiology, and evolution much more important."

The Foodborne Disease Burden Epidemiology Reference Group of the World Health Organization and the Government of the Netherlands funded this study. The study authors and editorialists have disclosed no relevant financial relationships.

Lancet Infect Dis. Published online June 27, 2014. Article abstract, Comment extract

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