[Anti-rubella virus IgG in urine: epidemiological application of a new enzyme-liked-immunosorbent assay (ELISA)].

Objectives: To evaluate the utility of urinary assessment for epidemiological studies of rubella, we measured anti-rubella virus immunoglobulin G (anti-RV IgG) using samples from pediatric patients with initial rubella infection, healthy volunteers who received a prophylactic inoculation of live rubella vaccine, and 3 years-old children undergoing a health examination at a community health center.

Methods: Blood and urine samples were collected from 12 of spontaneous rubella cases treated at 7 local pediatric clinics during acute and convalescent stages. In addition, blood and urine samples were collected from 17 healthy volunteers receiving prophylactic rubella vaccination immediately before, and 3 and 6-7 weeks after vaccination. Urine samples for anti-RV IgG measurement were also collected from 740 children 3 years of age at Odawara Community Health Center after obtaining informed consent from their parents. In addition, a questionnaire survey of the past history of prophylactic vaccinations was conducted. Serum titers of anti-RV antibody were measured using VIDAS Rubella-IgG and IgM (bioMerieux Japan Ltd.) and urinary titers of anti-RV IgG by ELISA (Otsuka Pharmaceutical Co., Ltd.).

Results: 1) The sensitivity and specificity for anti-RV IgG measurement in urine were 99.4% and 100%, respectively. 2) Six of 12 cases suspected of rubella infection were confirmed as initial rubella infection, and showed significantly increased anti-RV IgG titers in convalescent sera. Anti-RV IgG titers were also increased in the urine specimens. 3) In 17 subjects who received prophylactic inoculation with live rubella vaccine, serum titers of anti-RV IgG were increased 6-7 weeks after vaccination and anti-RV IgG was also detected in urine samples from all cases. 4) Urine samples from 80.9% of the children were positive for anti-RV IgG. In addition, 81.7% of the 698 cases, whose parents completed the questionnaire had received prophylactic inoculation with live rubella vaccine, confirmed by the vaccination records in maternal and child health handbooks. Furthermore, urine samples from 12.5% of children who had not received prophylactic live rubella vaccination were positive for anti-RV IgG.

Conclusions: The results of this study suggest that increased antibody titers after spontaneous rubella infection and prophylactic vaccination can be confirmed by measuring antibody titers in the urine. The results also suggest that urine sampling is useful for epidemiological studies of rubella because collection is simple, even from children.