Intussusception and rotavirus associated hospitalisation in New Zealand

Aims: To describe the epidemiology of intussusception and its relation to rotavirus associated hospitalisation in New Zealand. Methods: National hospital discharge data between January 1998 and June 2003 for all children younger than 3 years of age with intussusception were reviewed. Independently, children from the same age group, admitted to eight paediatric units with rotavirus gastroenteritis between May 1998 and May 2000, were identified prospectively. Epidemiological characteristics of cases with intussusception were compared with those of hospitalised rotavirus disease. Results: During the 5.5 year study period, there were 277 cases of intussusception and no deaths. Most ( 72%) occurred in the first year of life ( age adjusted incident rate 65 per 100 000 child-years, 95% CI 56 to 74). Risk of intussusception was less in females ( risk ratio 0.58; 95% CI 0.43 to 0.78) and for Maori ( risk ratio 0.52; 95% CI 0.35 to 0.77) when compared with European infants. In contrast to hospitalised rotavirus cases, intussusception peaked at a younger age and lacked seasonality. Conclusions: This study provides national baseline data on intussusception for future rotavirus vaccine programmes in New Zealand. Wild-type rotaviruses do not appear to have a major role in triggering intussusception. Prospective surveillance systems, using standardised case definitions and nested case-control methodology, are needed to further our understanding of the aetiology and epidemiology of intussusception.