Trends in syphilis incidence in Wisconsin, 1985-1991.

Between 1985 and 1991, increases in early (infectious) syphilis occurred among Wisconsin residents (1.8 to 18.4 cases per 100,000 persons). Males represented 54% and females 46% of early syphilis cases. Increases in early syphilis morbidity occurred among both white residents (0.9 to 1.5 cases per 100,000 persons) and black residents (25.4 to 330.4 cases per 100,000 persons). The largest increases occurred in Milwaukee County; in 1990, 90% of the cases of early syphilis in Wisconsin occurred among residents of Milwaukee County. In 1990 and 1991, age-specific rates of early syphilis among Milwaukee County residents were highest in the 20- to 24-year-old age group. Increases in early syphilis are likely to be due to increased participation in high risk behaviors. Between 1985 and 1991, congenital syphilis increased among all Wisconsin infants (1.4 to 38.9 cases per 100,000 live births), white infants (0 to 3.3 cases per 100,000 live births), and black infants (20.8 to 326.0 cases per 100,000 live births). Of the 28 mothers giving birth in Wisconsin in 1990 to infants meeting CDC criteria for congenital syphilis, 22 (79%) attended at least one prenatal care visit (mean, four visits; range, 1-10 visits). Of the mothers who attended at least one prenatal care visit, only 11 (50%) were tested for syphilis during their first prenatal visit, and 5 (23%) were not tested until the time of delivery. Inadequate prenatal screening for syphilis contributed to the increase in congenital syphilis.