Background: A substantial number of surveillance studies have documented rotavirus prevalence among children admitted for dehydrating diarrhea. We sought to establish global seasonal patterns of rotavirus disease before the introduction of widespread vaccination.
Methods: We reviewed studies of rotavirus detection in children with diarrhea published since 1995. We assessed potential relationships between seasonal prevalence and locality by plotting the average monthly proportion of diarrhea cases positive for rotavirus according to geography, country development and latitude. We used linear regression to identify variables that were potentially associated with the seasonal intensity of rotavirus.
Results: Among a total of 99 studies representing all 6 geographic regions of the world, patterns of year-round disease were more evident in low- and low-middle income countries compared with upper-middle and high-income countries where disease was more likely to be seasonal. The level of country development was a stronger predictor of strength of seasonality (P = 0.001) than geographic location or climate. However, the observation of distinctly different seasonal patterns of rotavirus disease in some countries with similar geographic location, climate and level of development indicate that a single unifying explanation for variation in seasonality of rotavirus disease is unlikely.
Conclusion: While no unifying explanation emerged for varying rotavirus seasonality globally, the country income level was somewhat more predictive of the likelihood of having seasonal disease than other factors. Future evaluation of the effect of rotavirus vaccination on seasonal patterns of disease in different settings may help understand factors that drive the global seasonality of rotavirus disease.
From the *National Center for Immunizations and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA; †Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ; ‡Fogarty International Center, National Institutes of Health, Bethesda, MD; and §Yale School of Public Health, New Haven, CT.
Accepted for publication November 8, 2012.
This work was partially supported by the Bill and Melinda Gates Foundation and the RAPIDD program of the Science & Technology Directorate, Department of Homeland Security and the Fogarty International Center, National Institutes of Health (VEP). The funders had no role in study design, data collection, analysis and interpretation, or writing of the report. Manish Patel had full access to all the data in the study and had final responsibility for the decision to submit for publication. The authors have no other funding or conflicts of interest to disclose.
Address for correspondence: Manish Patel, MD, Centers for Disease Control and Prevention, 1600 Clifton Rd, MS A-47, Atlanta, GA 30333. E-mail: email@example.com.