The prevalence of genital CTI in women requesting ToP was threefold higher in undocumented migrants than in women with legal residency permit (OR 3.2 (95% CI 1.4;7.3)). Insecure contraceptive methods (condoms, withdrawal, calendar) were frequent in both study groups. Compared to the control group, undocumented migrants used less hormonal contraception and were twice as likely to not use any contraception. The lesser use of contraception and the fact that over one third of women reported to have occasional partners may partially explain the high prevalence of CTI (12.8%) in this group.
There are no population studies on CTI prevalence in Switzerland. However, data from sentinel populations and laboratory findings have shown an overall prevalence of CTI of 2.8 to 4% [6, 14], which corresponds to the findings in our control group (4.4%) and is three times lower than the prevalence found here in undocumented migrants (12.8%). In a recent study conducted in women screened for ToP in Liverpool, the prevalence of CTI was 7.3%, mostly affecting women from 20 to 24 years of age . Studies in Latin America show CTI prevalence rates of 1.9% to 4.5% in Chile, Peru, Brazil, and Mexico [4, 10, 11] and a rate of 12.2% in women attending family planning clinics [4, 12]. A study in Italy offered free screening for STI to female migrant sex workers and found a CTI prevalence of 14% . The highest prevalence rates were observed in sex workers from Eastern Europe and, although not directly comparable, it suggests that undocumented migrant women in our study may actually be engaging in high risk sexual behaviours, whether on a voluntary basis or not. In any case, the encountered high prevalence rates of CTI and the availability of single-dose antibiotic treatment urges health professionals to consider systematic STI screening.
To the best of our knowledge, this is the first time in a Europe, that ToP characteristics were studied in undocumented migrants and compared to a local control group. Another strength of the study is the prospective and systematic inclusion of a relatively large number of this hard-to-reach population.
Limitations of the current study concern the representativeness of our sample from this hard-to-reach population and from the general population of pregnant women. Nevertheless, several aspects lead us to believe that this study reached a substantial proportion of pregnant, undocumented women requesting ToP in Geneva and is therefore representative of them: 1) The free medical care unit is well known by this hard-to-reach population; 2) The proportion of Latin Americans (78%) is similar to that found by other sources: by investigation of the origin of undocumented workers, the Geneva trade union recently found 76% were Latin Americans ; 3) In order to achieve optimal participation, undocumented women were enrolled in collaboration with the Woman's University Hospital, which is the only public Women's hospital in the Canton of Geneva. Finally, it is possible that the study sample still differs from the whole undocumented population of Geneva, which is, by definition, unknown. Although our control group was not a random sample from the general population, it was obtained by systematically sampling all the women with valid residence permits who were seen on selected days at the same hospital by the same nurse during the same time period that the sample of undocumented migrants was obtained.