Burden of rotavirus disease: A population-based study in Eastern Townships, Quebec.

Background: Since July 2010, the National Advisory Committee on Immunization of Canada has recommended rotavirus vaccination for all healthy infants. However, before implementing this vaccine in routine health programs, Canadian provinces need to establish current epidemiological data on rotavirus-associated acute gastroenteritis (AGE).

Methods: A retrospective cohort study of children <5 years of age with AGE from 2002 to 2008 was performed in Eastern Townships, Quebec (population in 2006: 298,780). Data were collected on visits to outpatient clinics, emergency department (ED) visits, hospitalizations (standard and short-stay units) and nosocomial AGE. The winter residual estimation and Brandt methods were used to estimate the proportion of AGE attributable to rotaviruses.

Results: During the six-year study period, a total of 1435 hospitalizations, 3631 ED visits and 6220 ambulatory care visits were attributed to AGE. The specific rotavirus burden was estimated to be 449 to 666 for hospitalizations, 1050 to 1361 for ED visits and 1633 to 1687 for outpatient visits. The epidemic curve showed a periodicity with higher incidence in March and April. Short-stay unit hospitalizations represented 58% of all hospitalizations. The annual incidence rate of rotaviruses was estimated to be 50 to 74 per 10,000 children for hospitalizations, 117 to 152 per 10,000 children for ED visits and 182 to 188 per 10,000 children for outpatient visits.

Conclusion: Most available retrospective studies probably underestimate rotavirus-associated hospitalizations because they do not take into account short-stay unit hospitalizations. Furthermore, these data on emergency and outpatient visits provide an exhaustive appraisal of the rotavirus burden, which serves as crucial information for the evaluation of immunization programs.