HIGH-INCIDENCE OF CONGENITAL-RUBELLA SYNDROME AFTER A RUBELLA OUTBREAK

Previous studies of the incidence of congenital rubella syndrome (CRS) after rubella outbreaks have been limited because most women with inf ection during the first trimester elected to have their pregnancies te rminated. After a rubella outbreak in 1991 we measured prospectively t he impact of maternal infection on CRS among the Amish in one county i n Pennsylvania. We compared rubella serology of Amish women delivering before and after the outbreak and cord blood rubella IgM from Amish a nd non-Amish infants. Before the outbreak 20% of Amish women were susc eptible to rubella; after the outbreak 4% were (P = 0.001). Of Amish i nfants 15% tested positive for rubella IgM; no non-Amish infants did ( P < 0.001). This rubella outbreak in a largely unimmunized community l ed to a high rate of CRS. The annual CRS rate among the Amish was 2130 /100 000 live births. Health care providers should promote immunizatio n in all clients and intensify efforts among the Amish.