In BC, syphilis and HIV testing are recommended for all women at prenatal screening for optimal clinical care and to prevent mother-to-child transmission of these infections.
Prenatal HIV screening has been universal since 1994, due to the growing number of BC women living with HIV and the effectiveness with which transmission to the baby can be prevented with antiviral treatment.
Hepatitis C virus (HCV) testing is not universally recommended, but targeted to women with specific risk factors for HCV infection such as HIV positivity and/or a history of injection drug use, among others.
While prenatal screening has clinical and public health importance, it is not routinely monitored at a provincial level in BC. We set out to evaluate trends in prenatal screening for syphilis, HIV, and HCV using linked laboratory and surveillance data, focusing on test uptake, diagnosis rates and prevalence.
For women undergoing any prenatal test between 2007 and 2011, we assessed their history of laboratory testing and reportable diseases through data linkage.
For each disease, we determined test uptake, or the percentage of women undergoing each type of testing. We determined the number of cases newly diagnosed at the time of screening as well as the prevalence (new plus previously diagnosed cases).
Summary of Evidence
Of the 233, 203 prenatally-screened women, test uptake for syphilis and HIV was in the desired range and improving over time. HCV uptake was 17.6% in 2007 and increased annually to 25.9% in 2011 (Figure 1).
Figure 1. Syphilis, HIV, and HCV Prenatal Screening Test Uptake, 2007 – 2011, BC
There were low rates of maternal syphilis (15.4 cases per 100, 000 women screened) and HIV new diagnoses (5.1 cases per 100, 000). The prevalence of HIV+ women undergoing prenatal screening was moderate and stable (45.9 cases per 100, 000). Mother-to-child transmission of congenital syphilis and HIV have been low and decreasing, with 2 cases per year of congenital syphilis from 2007-09 and no cases in 2010-12, and no infants found to have acquired HIV perinatally since 2008.
HCV new diagnoses at prenatal screening were high and decreasing (from 106 to 62 new diagnoses per 100,000). The prevalence of HCV+ women undergoing prenatal screening was high and stable (551.5 cases per 100,000) – about eight times more HCV+ women than HIV+ women undergo prenatal screening each year. About 40% of women with a prior HCV+ diagnosis on record were re-tested at a subsequent prenatal screen, suggesting their status was not known by their prenatal provider.
Implications for Practice
Prenatal screening for syphilis and HIV is high and increasing annually. The rates of new and prevalent infections highlight the need to continue the important and effective universal screening and treatment programs for HIV and syphilis.
HCV prevalence is high in this population. Finding ways to provide a woman’s HCV testing history at prenatal screening may reduce repeat testing of previously identified cases and help with patient engagement in further testing, counselling, care and, potentially, treatment outside of pregnancy.
For further information
See the full publication for more details: http://www.jogc.com/currentPastIssues_e.aspx#PastIssues
Drs. Naveed Janjua and Mark Gilbert, Clinical Prevention Services, BCCDC
- The College of Family Physicians of Canada and The Public Health Agency of Canada. Primary Care Management of Chronic Hepatitis C. Professional Desk Reference 2009. Available at: http://www.bccdc.ca/NR/rdonlyres/6C087975-B517-43FD-A579-FF644ABB9EA9/0/HEP_C_PC_Guide.pdf.
- British Columbia Centre for Disease Control. HIV Annual Report 2012. Available at: http://www.bccdc.ca/util/about/annreport/default.htm.