Hepatitis C virus among childbearing women in Scotland: prevalence, deprivation, and diagnosis

Objectives: ( A) To examine the prevalence and demographic characteristics of hepatitis C virus (HCV) infection among childbearing women in Scotland; and ( B) to determine the extent of maternal HCV infection diagnosed prior to birth. Methods: ( A) Residual dried blood spot samples from routine neonatal screening, collected throughout Scotland during March-October 2000, were unlinked from identifiers and tested anonymously for HCV antibodies; and (B) electronic record linkage of Scotland's databases of births and diagnosed HCV infections was performed. Results: (A) Of 30 259 samples, 121 were enzyme linked immunosorbent assay repeat reactive and 88 of these were confirmed as anti-HCV positive in the recombinant immunoblot assay, representing a seroprevalence of 0.29 - 0.40%. HCV seroprevalence was high among 25 - 29 year olds (0.4 - 0.57%), in high deprivation areas (0.92 - 1.07%), and in Greater Glasgow (0.83 - 0.96%) and Grampian (0.38 - 0.62%). Adjusted relative risk for HCV infection was highest among residents in high deprivation areas of Glasgow (7.2 (95% confidence interval 2.0 - 25.5)). ( B) Of 121 HCV infections found among women at delivery, 24% and 46% were estimated to have been diagnosed prior to pregnancy and birth, respectively. Conclusions: HCV prevalence among Scottish childbearing women is consistent with that expected from injecting drug use. Based on reported rates of mother to child transmission, 8 - 11 paediatric infections are expected per annum. Diagnosis in only 24% of infected women prior to pregnancy indicates the extent to which HCV goes unrecognised in the injecting community. The current HCV screening approach - to test only those with a history of injecting drug use ( or other risk factors for infection) - identifies approximately a quarter of previously undetected infections among pregnant women.