Researchers from the New Vaccine Surveillance Network prospectively evaluated a multi-state group of young children with and without acute gastroenteritis (AGE) to ascertain the burden of norovirus and rotavirus. Children <5 years of age seeking medical attention for AGE at hospitals, emergency departments (ED), or outpatient clinics in 3 US counties from 2009 to 2010 were enrolled. AGE was defined as ≥3 episodes of diarrhea and/or ≥1 episode of vomiting in 24 hours. Healthy control children <5 years old were also enrolled at well-child visits during 2009 and were frequency-matched to enrolled children with AGE by age and calendar month and were required to be free of AGE symptoms for 14 days and free of respiratory tract infection for 3 days. Stool specimens were collected from children with AGE within 10 days of the visit or admission and from controls within 5 days of enrollment. Fecal specimens were tested for norovirus by real-time polymerase chain reaction assays and for rotavirus by enzyme immunoassay. Estimates of both costs and rates of hospitalization, ED visits, and outpatient visits were calculated for each virus and extrapolated to the US population of children <5 years old.
There were 1,897 children with AGE and 806 healthy controls enrolled in the study. Fecal specimens were collected on 1,295 children with AGE and 493 controls. Overall, norovirus was detected in 21% of children with AGE and 4% of controls; rotavirus was detected in 12% of children with AGE and <1% of controls.
Forty-seven percent of medically- attended norovirus infection occurred in children 6 to 18 months old. Norovirus disease incidence peaked in January, but was noted to occur year-round. The estimated mean rates of hospitalization, ED visits, and outpatient visits per 10,000 children over the 2-year period for norovirus were 7.2, 140.7, and 319.0, respectively, with an associated cost exceeding $273,000,000 annually. For rotavirus, the rate of hospitalization per 10,000 was 11.6 in 2009 and 1.1 in 2010; the rate of ED visits per 10,000 was 111.1 in 2009 and 8.3 in 2010; and the rate of outpatient visits per 10,000 was 119.1 in 2009 and 0 in 2010.
The authors conclude that norovirus has become the most common cause of medically-attended AGE in children aged <5 years.
Dr Tolan has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.
This prospective surveillance study provides data on rates of norovirus infection in children aged <5 years. Interpretation of the results is potentially limited by concerns about how representative the populations sampled are of the entire country. Data on population-based rates were derived from US Census data from 2000, which may no longer be valid. Furthermore, the rates observed may not reflect true year-to-year...