Setting, study participants & enrolment
In Peru, sex work is permitted by FSW who are registered at a public health clinic and are of 18 years of age or older. Registration requires monthly health assessments which are free of charge, including treatment . Approximately two-thirds of Lima’s estimated 15,000 FSW are registered. The Centro de Salud ‘Alberto Barton’ (CSAB), located in the port city of Callao-Lima, provides healthcare to registered FSW, while an associated mobile clinic provides care to unregistered FSW. These monthly healthcare checks are provided by Peruvian Ministry of Health clinicians, and include genital examination and collection of cervical and vaginal swabs for basic onsite microbiology (including Gram stain, wet mount and KOH staining) in addition to gonococcal culture. Syphilis screening (by non-treponemal assay) is performed quarterly and HIV testing is performed twice per year. If required, much of the treatment is syndromic as per the National STI Guidelines .
FSW presenting for medical assessment at either of these clinics between November 2008 and January 2011 were invited to participate in this cross-sectional study. Unregistered and registered FSW were eligible to participate, with registration status determined on routine assessment. Unregistered FSW were offered enrolment (if eligible) when presenting for routine assessment at the mobile clinic. FSW 18 years of age or older were eligible for inclusion. Informed consent was obtained from all study participants. The study was approved by the Institutional Review Boards of the University of Washington, Universidad Nacional Mayor de San Marcos, the Directorate of Callao, and US Naval Medical Research Unit No. 6 (NAMRU-6), Callao, Peru.
All participants completed a face-to-face questionnaire to provide data on sociodemographic and behavioral variables and underwent genital examination with collection of vaginal, endocervical and blood samples. Genital examination was performed by one of the regular clinic doctors as an assigned study physician. Cervicitis was defined as the presence of mucopus and friability in concurrence with the Centers for Disease Control and Prevention recommendations . PID was defined as cervicitis in the presence of lower abdominal pain plus cervical motion tenderness, adnexal tenderness or uterine tenderness.
Saline wet-mount microscopy was performed on cervical samples for detection of Trichomonas vaginalis (TV) at an on-site laboratory at CSAB. Further cervical specimen testing occurred at NAMRU-6 laboratories in Lima, Peru. One cervical sample was placed in specimen transport medium (Digene Diagnostics, Silver Spring, MD) for molecular testing of Chlamydia trachomatis (CT), Neisseria gonorrhoea (GC) and Human Papillomavirus (HPV). CT and GC testing was performed using Amplicor CT/GC PCR according to the manufacturer’s instructions (Roche, Pleasanton, California, USA). HPV DNA was extracted and PCR analysis performed according to methods described elsewhere . Vaginal swabs were evaluated with Gram stain, KOH and saline wet mount tests for the detection of candidiasis, TV and BV. In accordance with recently standardised research definitions, BV was diagnosed by positive Amsel criteria and Nugent scoring . All vaginal swab testing occurred at CSAB.
Blood samples were transported to NAMRU-6 laboratories for analysis. Serum was screened for HIV using a Vironostika HIV Ag/Ab assay (bioMeriéux, Marcy l′Etoile, France); positive assays were confirmed by line immunoblot assay (INNO-LIA HIV I/II Score, Innogenetics, Gent, Belgium). Serum samples were also tested for HTLV-1/2 antibody by ELISA assay (BioElisa HTLV I/II 5.0 BioKit, Llica d’Amunt, Barcelona, Spain) with confirmatory testing using line immunoblot assay (HTLV I/II score, Innogenetics, Gent, Belgium). Serum was screened for syphilis using Rapid Plasma Reagin (RPR-nosticon II, bioMeriéux, Marcy l′Etoile, France) and confirmed by Treponema Pallidum Hemagglutination Assay (TPHA; Syphagen TPHA - Biokit, Llica d’Amunt, Barcelona, Spain). Women with positive STI test results were counselled and treated according to Peruvian Ministry of Health Guidelines .
All data were double entered into an electronic database and analyzed using STATA, version 12.0 (StataCorp, College Station, TX). Bivariate associations of cervicitis with sociodemographic, behavioral, and biological variables were examined using Chi-squared tests to determine significant differences between groups. Logistic regression was used to determine whether sociodemographic, behavioral, or other sexual health-related characteristics were associated with the diagnosis of cervicitis. Both unadjusted and adjusted logistic models were fit to estimate odds ratios (OR) and 95% confidence intervals (95% CI). For sociodemographic variables, we used the criterion of a greater than 10% change in the OR to identify confounders in adjusted models. For biological variables, we specified the presence of genital tract infections associated with both cervicitis and bacterial vaginosis (namely CT, GC or TV) as a priori confounders in an adjusted model. A significance level of 0.05 was used for all hypothesis tests.