[Clinical evaluation of a norovirus antigen detection test in pediatric patients and study targeting application to...

Typical causative viruses of viral gastroenteritis in childhood are Norovirus(NV), Rotavirus(RV), and Adenovirus (AV). It is difficult to specify the type of virus based on the clinical symptoms, necessitating a search for the causative virus. Antigen testing is the mainstay for the definitive diagnosis of RV and AV. Molecular biology testing, however, is the mainstay for NV, and problems related to the rapidity and simplicity of the test have been a pending issue for many years. In this study, the clinical performance of an NV antigen detection test was investigated in children, and its application to combating infection was considered. Among 181 children with gastroenteritis tested by RT-PCR, there were 87 children (48.0%) showing positive NV findings in stool samples. Taking RT-PCR as the gold standard, the correlation with the antigen detection test showed a sensitivity of 76.0%, specificity of 100%, and a concordance rate of 89.5%. Results obtained in the basic study showed that the antigen detection test could be useful in everyday practice. As a result of studying how long the virus is shed in the feces of children infected by NV, however, the percentage of positive findings on RT-PCR testing was 16 of 17 (94.1%) on day 7 of illness and similarly 6 of 7 (85.7%) on day 14. However, only one case was positive using the antigen detection test on day 7 of the illness, and all were negative on day 14. The viral load of NV is assumed to drop below the sensitivity of the antigen detection test within 7 days. The appropriate method of use remains to be established, but the antigen detection test for NV appears to be able to make a contribution in everyday practice.