GHENT UNIVERSITY Karoline FONCK - International Centre for ...

We believe that the observed decline in syphilis rates in pregnant women in Nairobi is a real
event. Population differences and consultation bias cannot be excluded but are not likely to
play a major role, as population characteristics (age, parity, ethnicity) have remained
unchanged over the years. The number of women screened has increased substantially
since 1995, which could be responsible for a selection bias. Most likely however, the
coverage of the program, expanding slowly, was not complete until 1995-96, and explains
the rising numbers of women in the study. Obviously, the syphilis control program by itself
might have an impact on the declining syphilis rates. The decentralized syphilis program was
initiated in Nairobi in June 1992. From that time high numbers of syphilis seroreactive women
in the reproductive age group have been adequately treated for syphilis in pregnancy. Since
the mean interval between 2 pregnancies is about 2 years for Kenyan women, some of them
may attend the clinics for a subsequent pregnancy and will not be RPR positive anymore
because of previous treatment, unless re-infection occurred.
Syphilis prevalence in pregnancy seems to show a large spread in different African countries.
In a nationwide study performed in Burkina Faso in 1994-95, a syphilis prevalence of 2.5%
was found in pregnant women (Sangare 1997). In Rwanda, in a prospective cohort study in
1992-93, 5% of the pregnant women tested positive for syphilis (Leroy 1995). Guarenti et al.
reported a syphilis prevalence of 4.8% in pregnant women in 4 different areas in Tanzania in
1995 (personal communication). A high syphilis prevalence was found in South African
publications, varying from 17% in 1990 (Bam 1994) to 9.3% in 1992 (Qolohle 1995) and
6.5% in 1994 (Wilkinson 1997). These figures could reflect a decline in syphilis prevalence in
South Africa between 1990 and 1994, but are derived from different settings, not allowing
calculating trends over time.
In conclusion, this study provides data on trends in syphilis screening results in a set
population of pregnant women in Nairobi between 1994 and 1997. Until 1995 the syphilis
prevalence was on the rise, followed by a marked decline in 1996 and 1997. Population bias
or other unrelated factors could theoretically play a role, but we believe that this decline is
real suggesting an effect of prevention and intervention programs aimed at sexual behavior
modifications, changes in health-seeking behavior and improved health services.
PREVALENCE AND RISK FACTORS OF STI 36