Epidemiological Characteristics of Congenital Rubella Syndrome Cases during Rubella Epidemic in Japan, 2012–2014

Abstract

BackgroundRubella infection during the first 20 weeks of pregnancy can cause congenital rubella syndrome (CRS). The main defects of CRS are known as classic triads; hearing impairment, congenital heart disease, and cataract. In Japan from 2011 to 2013, rubella outbreak occurred mainly among adults in their 20s to 40s, and consequently notification of CRS cases increased.MethodsWe collected information of epidemiological characteristics regarding all reported CRS cases and their mothers retrospectively by questionnaire to the physicians and interview to the several members of patients’ association of CRS. We conducted descriptive analysis to evaluate public health impact on CRS in Japan.ResultsA total of 45 CRS cases were reported from October 2012 to October 2014. Majority of cases (96%: 43/45) were diagnosed at less than three months old, except for two cases whose diagnoses at 9 months old and 13 months old due to late onset of cataract and hearing impairment. Males accounted for 56% (25/45). The median gestational week at birth was 38 weeks (range: 31 to 41 weeks) and mean birth weight was 2,171 g (standard deviation: ± 626 g). Frequencies of clinical manifestations at the time of diagnosis revealed that 67% (30/45) of cases had hearing impairment, 58% (26/45) had congenital heart disease, and 16% (7/45) had cataract. The most frequent heart diseases was patent ductus arteriosus (77%: 20/26), followed by pulmonary stenosis (15%: 4/26), and atrial septal defect (15%: 4/26). Only 7% (3/45) had classic triads. Thrombocytopenia which accounted for 73% (33/45) was the most frequent manifestation developed other than classic triads. Eleven cases died at the time of investigation, indicating 24% of case fatality proportion of reported CRS cases in this outbreak. Among ten cases died before 6 months old, nine were complicated by congenital heart disease. None of the mothers of reported CRS cases had two doses of Rubella Containing Vaccine (RCV) before pregnancy; meanwhile 24% (11/45) of mothers had one dose of RCV.ConclusionHigh case fatality proportion of CRS pointed out obvious high public health impact in Japan. Vaccination of two doses of RCV before pregnancy is necessary to preventing CRS.Disclosures All authors: No reported disclosures.