Syphilis infection in pregnancy causes high rates of fetal and early infant death and adversely affects the health of women. The prevalence of reactive syphilis serology among pregnant women in Africa ranges from 6% to 16%[1-5]. The findings of pregnancy studies conducted prior to instigating syphilis treatment programmes indicate that untreated syphilis has one of the following outcomes: approximately a third of cases result in second trimester spontaneous abortions or perinatal deaths; a third result in congenitally infected infants; and a third result in healthy uninfected infants. This high level of perinatal mortality has serious psychological and cultural implications for women in societies where fertility and childbearing are a critical part of social standing and self-image.
Although there is a simple screening test for syphilis, and penicillin continues to be effective for its treatment, the disease remains a largely ignored maternal and perinatal health problem in most sub-Saharan African countries. The implementation of an effective antenatal screening and treatment intervention requires a functioning health care system that collects blood specimens from women early in pregnancy, accurately carries out and interprets syphilis serology tests and reports them to the health facility, and promptly treats positive women and their partners. Currently, the resources required for antenatal syphilis screening and treatment programmes are either lacking or difficult to sustain. The need for such programmes or the need to sustain an existing programme by diverting resources frequently has to be justified by repeated demonstration of the extent of adverse outcomes. Also, although programmes of this type are available in large towns in many African countries, they are operationally ineffective because of centralized testing, which results in low follow-up and treatment of positive women.
In Malawi, despite national policy, routine antenatal syphilis screening programmes were discontinued in many rural district hospitals when they could not sustain the programmatic requirements. In such a setting and within the context of a population-based study of malaria prevention in pregnant women, we examined and quantified the prevalence of and risk factors for acquiring syphilis and its outcomes among a rural population of pregnant women.
Enrolment and follow-up
We carried out a prospective study of malaria chemoprophylaxis among pregnant women between 1987 and 1990 in a rural district in Malawi. Consecutive pregnant women who were attending any of four antenatal clinics were enrolled and followed up throughout pregnancy and then once every two months for more than a year after delivery. Because 93% of pregnant women in Malawi attend antenatal care (L. Schultz et al., unpublished results, 1993) and the study women and their infants were followed up in the community, the study can be considered to be population-based. The women received routine antenatal care, including monthly visits, tetanus toxoid, iron supplements, and malaria chemoprophylaxis, but there was no routine syphilis screening through the clinic system. Stored blood specimens collected during the antepartum period and at delivery as part of the malaria study were later tested serologically for syphilis.
Syphilis serology testing and case definition
The sera were tested in 1991-92 for syphilis, using Venereal Disease Research Laboratory (VDRL) or rapid plasmin reagin (RPR) tests and a microhaemagglutination assay for antibodies to Treponema pallidum (MHA-TP). All VDRL/RPR reactive sera were diluted to an endpoint titre.
The definitions of syphilis used in the study were based on the serological findings expected for the various stages of the disease. The last cases of yaws in Malawi occurred prior to 1977, and this condition is considered to have been eradicated from the country. …