WHO recommends rapid dual HIV/syphilis tests for pregnant women

Syphilis is the second most common cause of stillbirth in the world but testing and treatment for this sexually transmitted infection (STI) among pregnant women is poor in many countries, and much less common in antenatal care than HIV testing and treatment.

Globally, there has been marked progress towards eliminating mother-to-child transmitted HIV but progress is much slower for preventing congenital syphilis, with around 660,000 cases reported in 2016. More than 350,000 of these led to birth complications, including 200,000 stillbirths and neonatal deaths.

To close the gap, the WHO has released a new policy brief recommending countries offer a single finger-prick rapid diagnostic test that screens for HIV and syphilis simultaneously.

These simple tests can detect antibodies to both Treponemal pallidum (the cause of syphilis infection) and HIV, and can be carried out in health facilities rather than being sent for laboratory analysis. This means results are available quickly, enabling those who test positive for either infection to start treatment. They are also cheaper compared to standard, separate testing.

However, because the dual test does not differentiate between active or past syphilis infection, a past syphilis infection may still produce a positive result. For this reason, the WHO recommends that any woman testing positive for syphilis be prescribed benzathine penicillin then referred for further testing for a final, confirmatory diagnosis.

Countries introducing the dual HIV/syphilis test into antenatal care will need to revise their HIV testing strategy for pregnant women. This is because the testing strategy needed for dual detection of HIV and syphilis differs from the recommended strategies for separately testing for HIV or syphilis. In particular, it is important not to offer the dual test to women living with HIV who are taking antiretroviral treatment, those with an existing syphilis infection which is being treated, and for retesting for HIV.

In addition to increasing syphilis testing and treatment, use of the dual-purpose test will save costs in several ways. It has the potential to simplify the training of testers because it requires staff to learn one testing method rather than two. It will also reduce storage and transportation costs because rapid diagnostic tests do not require refrigeration and will reduce waste disposal.

The policy brief includes a checklist of issues to consider when implementing dual testing in order to maximise its benefits, such as the need to provide the service in community settings to reach pregnant women from key populations who are at heightened risk for both HIV and syphilis.