Screen test: detecting and treating syphilis in pregnant women in Tanzania

Up to 17 per cent of pregnant women in sub-Saharan Africa are infected with syphilis. This has serious consequences for their baby’s health. Research co-ordinated by the London School of Hygiene and Tropical Medicine looked at poor pregnancy outcomes due to syphilis in Mwanza Region, Tanzania, and the impact of treatment.

Researchers tested 380 pregnant women for syphilis at delivery. In this population, they found that 61 per cent are uninfected, 19 per cent have high-titre active syphilis, seven per cent have low-titre active syphilis and two per cent have past/treated syphilis infection. Compared with uninfected women, those with high-titre active syphilis have:

• four-fold increased risk of any adverse pregnancy outcome
• eighteen times greater chance of stillbirth
• three times the probability of having a low birth weight infant
• six-fold greater risk of premature delivery
• higher rates of illiteracy and poor housing.

Among unscreened women, half of all stillbirths, a quarter of premature live births and 17 per cent of all adverse pregnancy outcomes are due to maternal syphilis. Antenatal syphilis screening is highly cost-effective and could reduce this huge burden. But what is the best strategy for treatment?

In a related study, the researchers screened women for syphilis at antenatal clinics. They treated 133 women with high-titre syphilis and 249 women with low-titre syphilis using a single injection of benzathine penicillin. They compared birth outcomes among these women with 950 uninfected women. The study showed that:

• The mean gestational age when women first access antenatal care is 24 weeks.
• 17.3 per cent of negative women have an adverse pregnancy outcome compared with 15.2 per cent of women treated for syphilis.
• There is no significant difference in the proportion of stillborn or low birth weight infants between the groups.
• With the exception of stillbirth, women with high-titre active syphilis have more frequent adverse birth outcomes if they are treated at a later stage of gestation than if they are treated in the first half of their pregnancy.

Syphilis infection rates, levels of stillbirth and premature birth, and the gestational age at first antenatal visit in Mwanza are similar to those in other parts of the continent. Policy-makers and practitioners addressing maternal and childhood health throughout sub-Saharan Africa should:

• prioritise syphilis screening and same-day treatment as an essential part of antenatal care
• educate pregnant women that untreated maternal syphilis is a danger to the unborn baby and that it can be diagnosed and treated
• encourage women to visit antenatal clinics that screen for syphilis early in their pregnancy
• provide other antenatal services that can improve the health of mother and infant, such as vitamin and iron supplements, anti-malarial drugs and treatment of other reproductive tract infections
• screen women for syphilis at delivery if they have not been to an antenatal clinic so that both mother and child can receive treatment
• consider mass syphilis treatment in pregnancy if a screening programme is not feasible.

Source(s):
‘Syphilis in pregnancy in Tanzania. I. Impact of maternal syphilis on outcome of pregnancy’, The Journal of Infectious Diseases 186: 940-947, by D. Watson-Jones, et al., 2002
‘Syphilis in pregnancy in Tanzania. II. The effectiveness of antenatal syphilis screening and single-dose benzathine penicillin treatment for the prevention of adverse pregnancy outcomes’, The Journal of Infectious Diseases 186: 948-957, by D. Watson-Jones, et al., 2002

Funded by: Wellcome Trust

id21 Research Highlight: 28 August 2003

Further Information:
Deborah Watson-Jones
Department of Infectious and Tropical Diseases
London School of Hygiene and Tropical Medicine
London
WC1E 7HT
UK

Contact the contributor: deborah.watson-jones@lshtm.ac.uk

London School of Hygiene and Tropical Medicine, UK

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