Rubella outbreak on Tokunoshima Island in 2004: serological and epidemiological analysis of pregnant women with rubella.

AIM

This paper presents the serological and epidemiological background of the rubella-infected pregnant women following the rubella outbreak throughout Tokunoshima Island that occurred after the revision of the immunization law in Japan.

METHODS

Twelve of 149 pregnant women managed in Miyagami Hospital were enrolled as having a high risk for congenital rubella infection. They were interviewed about their immunization history with rubella vaccine, the presence of rash, onset of rash, and the presence and timing of contact with rubella-infected patients. The obstetric histories were investigated for past rubella HI antibody titer. Nine of 12 women continued their pregnancy and delivered a baby. A serological test for rubella IgM antibody and a reversed transcription-nested PCR assay using umbilical cord blood and the newborn urine for virus genome detection were performed for all babies. We also enrolled all 309 mothers who delivered during the last 2 years in Miyagami Hospital, and retrospectively collected their rubella HI titers.

RESULTS

Congenital rubella syndrome (CRS) and congenitally infected babies were born from 12 high-risk mothers. In our study, six pregnant women to be immunized by a catch-up program showed a lack of immunity to rubella. The remaining six women had low rubella immunity. Nine acquired rubella from members of their family, including their husband. The incidence of negative HI titer was 25% in women less than 25 years old who delivered during the last 2 years in this hospital.

CONCLUSIONS

More intensive immunization should be considered to eradicate CRS completely in Japan.