An epidemiologic investigation of a rubella outbreak among the Amish of northeastern Ohio.

From April 1990 to April 1991, 278 cases of rubella were reported to the Ohio Department of Health. Of these, 276 (99 percent) were among the Amish of northeastern Ohio. The outbreak involved eight counties in an area that contains large settlements of Old Order Amish. Members of this community of Amish frequently take religious exemption from recommended immunization practices and are believed to represent a high proportion of Ohio's rubella-susceptible persons. Vaccination history was known only for 146 of the Amish people. Of those, only four had a positive history of rubella vaccination. Of the 276 Amish with cases of rubella, 65 (24 percent) were younger than age 5 years, 104 (38 percent) were ages 5-14, 46 (17 percent) were ages 15-19, 32 (12 percent) were ages 20-29, 6 (2 percent) were ages 30 or older, and age was not reported for 23 (8 percent). The ratio of males to females with rubella was 1:1. Five women of the Amish community were pregnant; four had been ill with symptoms consistent with rubella. Three were in their first trimester. Congenital rubella syndrome did not occur in any of the four live births. Serology was available for only the two non-Amish people, and both were acute phase serum-positive for Immunoglobulin M.