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Trichomoniasis is nowadays the most prevalent non-viral sexually transmitted infection in the world. In Senegal, the epidemiology of trichomoniasis is not well known. The current study aimed at assessing the prevalence and factors associated with T. vaginalis infection among women with vaginal discharge. Methods. A retrospective analysis of laboratory records from patients referred at the Fann Teaching Hospital in Dakar, Senegal, for vaginal discharge was carried out. The study covered the period from 2006 to 2011. For each participating woman, a vaginal swab was collected and a wet mount smear performed immediately. Optic microscopic examination with 40x magnification was done to detect T. vaginalis and assess biological modifications such as presence of epithelial cells, white blood cells, and red blood cells. A gram stained smear was also performed and examined under oil immersion (100x magnification) to assess the vaginal flora. Results. Overall, 3893 women were enrolled with a mean age at 31.2 ± 10 years. The prevalence of Trichomoniasis represented 4.8%, 95%CI(3.1-5.7) and it was lower among women less than 30 years (4.1%), while divorced women more likely to be infected compared to married and single women (aOR:2.1, 95%CI (1.2-3.7)). Trichomoniasis was associated with abnormal vaginal flora such as type III (aOR:2.6, 95%CI(1.5-4.4)) and type IV (aOR:3.3, 95%CI(2.1-5.3)). In addition, patients with erythrocytes excretion were more likely to be infected by T. vaginalis (aOR:2.8, 95%CI(1.9-3.9). Conclusion. Trichomonas vaginalis remains prevalent among sexually active women. Strategies aiming at improving disease awareness in these high-risk groups are needed to improve trichomoniasis prevention but extensive epidemiological data are still needed for a better understanding of the disease transmission dynamic.

Chapter one

1. Introduction

Trichomoniasis is the most prevalent non-viral sexually transmitted infection in the world [1]. Trichomonas vaginalis, the causative agent is a protozoan parasite infecting the urogenital tract of both females and males [2]. It is reported to be 250 million new cases worldwide every year [3] and Trichomoniasis accounts to almost half of curable sexually transmitted infections according to the world health organisation [3, 4]. In general, the infection is asymptomatic in men although it can be associated with urethral discharge and dysuria [5], while infected women can have different symptoms consisting in yellowish-green frothy discharge, purities, dysuria, and the strawberry cervix which is recognized by punctuates haemorrhagic lesions [5]. Infection by Trichomonas vaginalis among women can lead to serious complications such as adverse pregnancy outcomes that appear by preterm rupture of membranes, preterm delivery, low birth-weight infants, infertility, and cervical cancer [6]. Moreover, studies have shown an increased risk of HIV transmission among individuals infected by T. vaginalis [7]. Trichomonas vaginalis transmission is very heterogeneous and depends on several factors; it is established that socioeconomic status, age, hygiene habits, sexual behaviour, phase of the menstrual cycle, and other concomitant sexually transmitted infection can play a key role on the disease burden [8, 9]. The prevalence and the average duration of Trichomonas infection mainly depend on the health care seeking behaviour of population and their access to health care [10]. Primary prevention of Trichomonas vaginalis infection often relies on health promotion interventions to improve diseases awareness and behaviour change [11]; but male circumcision represents an important means for the prevention of T. vaginalis transmission and several studies have shown that partners of circumcised men are less at risk of acquiring sexually transmitted infections including Trichomoniasis [12, 13]. Oral metronidazole remains the recommended drug regimen for the treatment of trichomoniasis and concurrent treatment of sexual partners is recommended to prevent reinfections [14].

In many settings including Senegal, patients presenting at primary care units with signs suggestive of STI (urethral discharge, vaginal discharge syndromes) are often being diagnosed and managed presumptively using a syndromic approach based on WHO guidelines [15]. But studies have shown that a syndromic-based approach in some settings may lack sensitivity and specificity and can lead to mismanagement of several STI including trichomoniasis [16, 17]. In addition, biological confirmation of T. vaginalis infection in many primary care units remained at a low level due to lack of appropriate diagnostic tool and community prevalence data remained scarce [18, 19]. Thus, limited data regarding the epidemiology of Trichomoniasis are available especially among at risk population such as women of reproductive age. A better understanding in the epidemiology of T. vaginalis is thus needed and may help shape existing control strategies and treatment practices regarding STI in Senegal. To overcome these gaps, this six-year trends analysis was conducted to provide insight into the prevalence of T. vaginalis infection among women with vaginal discharge referred at the Fann teaching hospital in Dakar, Senegal, and explore potential factors associated with T. vaginalis infection.

2. Methods

2.1. Study Settings

The study was conducted at the Fann teaching hospital, which is a public referral hospital, located in the capital city of Dakar. Population access to this referral hospital including access to laboratory services is easy by simple appointment. Although data on trichomoniasis in Senegal has scarcely been described, prevalence of STI in the general population is still low [20, 21] and their management under routine conditions usually refers to a syndromic based-approached [16].

2.2. Design and Population

The present study is a retrospective analysis of data from patients referred at the Fann teaching hospital for vaginal discharge during the period from 2006 to 2011. Participating women were eligible if they had at least 18 years. Women, who were previously screened for STI within the same study period, were excluded in the analysis. A code was given to each enrolled participants and data on women’s sociodemographic characteristics and residency were collected from participant’s medical records based on prior permission from the administration officials of the Fann Teaching Hospital.

2.3. Specimen Collection and Processing

For each participating woman, a vaginal swab was collected and a wet mount smear was performed immediately as part of a routine diagnostic procedure for a motile parasite. The wet mount smear was examined using optical microscopy with 40x magnification to detect T. vaginalis and assess biological modifications such as presence of epithelial cells, white blood cells, and red blood cells. Trichomonas vaginalis infection was considered on the basis of a positive result from a wet mount microscopy of motile trichomonad. The magnitude of white and red blood cell within the vaginal discharge was classified as follows: (i) rare 1 to 5 cells/field microscopy, (ii) moderate: 6 to 10 cells/field microscopy, (iii) many: 11 to 20 cells/field microscopy, and (iv) high: 21 cells and above/field microscopy. In addition, a gram stained smear was performed to characterise the vaginal flora using Nugent scoring [22]. Briefly, each Gram-stained smear was evaluated for the following morphotypes under oil immersion (100x magnification): large gram-positive rods (lactobacillus morphotypes), small gram-variable rods (G. vaginalis morphotypes), small gram-negative rods (Bacteroides spp. morphotypes), curved gram-variable rods (Mobiluncus spp. morphotypes). Each morphotype was quantitated from 1 to 4+ with regard to the number of morphotypes per oil immersion field and the vaginal flora was characterised as follows: Type I: less than 1 morphotype; Type II: 1 to 4 morphotypes; Type III: 5 to 30 morphotypes; Type IV: 30 or more morphotypes) as described elsewhere [22]. Types I and II were considered as normal vaginal flora, while types III and IV were considered as abnormal flora.

2.4. Statistical Methods

Data were entered into Filemaker Pro™ software and extracted for cleaning and analysis using STATA software (version 14.0 – StataCorp LP, Texas). For binary data, percentage was used to assess the frequency of each outcome with a 95% confidence interval (95%CI). For continuous data, mean and standard deviation were used to describe normally distributed variables. Characteristics of all women included in the study were tabulated. Proportions were compared using chi square test (univariate analysis). Prevalence of T. vaginalis was calculated and expressed as proportion with 95%CI. To assess factors associated with T. vaginalis infection a multivariate logistic regression with adjustment on covariates such as age group, study period, and marital status was done. From the final model, adjusted odds ratios were derived with their 95%CI. Model validity was tested using the Hosmer-Lemeshow goodness-of-fit test. The performance of the final model was assessed by the area under the curve and Akaike and Bayesian information criterion; in addition, a test for multicolinearity between variables was done using the variance inflation factor. Significance level of the different tests was 0.05, two-sided.

3. Results

3.1. Participant’s Characteristics at Enrolment

Overall, for the six-year period, 3893 women with vaginal discharge were referred at the Fann Teaching Hospital for aetiological investigation. The mean age of the study participants was 31.2 ± 10 years and the majority were below the age of 35 years. Indeed, 25.9% of the women were less than 25 years old and 30.7% of them had an age ranging from 25 to 35 years. Married women represented a proportion of 53.8%, while single and divorced women represented, respectively, 20.1% and 6.5%. Table 1 summarises study participants characteristics at enrolment.


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