Global prevalence of norovirus in cases of gastroenteritis: a systematic review and meta-analysis.

Background: Despite substantial decreases in recent decades, acute gastroenteritis causes the second greatest burden of all infectious diseases worldwide. 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.

Methods: We searched Embase, Medline, and Global Health databases from Jan 1, 2008, to March 8, 2014, for studies that used PCR diagnostics to assess the prevalence of norovirus in individuals with acute gastroenteritis. We included studies that were done continuously for 1 year or more from a specified catchment area (geographical area or group of people), enrolled patients who presented with symptoms of acute gastroenteritis, and used PCR-based diagnostics for norovirus on all stool specimens from patients with acute gastroenteritis. The primary outcome was prevalence of norovirus among all cases of gastroenteritis. We generated pooled estimates of prevalence by fitting linear mixed-effect meta-regression models.

Findings: Of 175 articles included, the pooled prevalence of norovirus in 187 336 patients with acute gastroenteritis was 18% (95% CI 17-20). Norovirus prevalence tended to be higher in cases of acute gastroenteritis in community (24%, 18-30) and outpatient (20%, 16-24) settings compared with inpatient (17%, 15-19, p=0·066) settings. Prevalence was also higher in low-mortality developing (19%, 16-22) and developed countries (20%, 17-22) compared with high-mortality developing countries (14%, 11-16; p=0·058). Patient age and whether the study included years of novel strain emergence were not associated with norovirus prevalence.

Interpretation: 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.

Funding: The Foodborne Disease Burden Epidemiology Reference Group (FERG) of WHO and the Government of the Netherlands on behalf of FERG.