Prevalence and Risk Factors for Trichomonas vaginalis Infection among Pregnant Women Seeking Primary Health Care in Sana'a City, Yemen

Objective: To determine the prevalence and risk factors for Trichomonas vaginalis infection among pregnant women seeking health care in Sana’a city. 
Methods: This cross-sectional study was conducted among pregnant women seeking health care in private clinics and governmental primary health care centers in Sana’a during the period from October 2014 to June 2015. Data on sociodemographic and clinical characteristics as well as possible risk factors of T. vaginalis infection were collected from 287 pregnant women using a pre-designed questionnaire by trained researchers. Vaginal discharges were then collected and examined microscopically for motile T. vaginalis trophozoites. 
Results: The overall prevalence of T. vaginalis infection was 11.1%, with a higher infection rate among pregnant women aged 26-40 years old, housewives and rural residents. Age, literacy status and the age at first sexual intercourse were signiﬁcantly associated with T. vaginalis infection among pregnant women. Presence of vaginal discharge (OR = 8.33; 95% CI: 2.47–28.03, P <0.001), itching (OR = 2.57; 95% CI: 1.02–6.48, P = 0.027) and presence of unpleasant odor (OR = 4.37; 95% CI: 1.63–11.70, P = 0.001) were the clinical manifestations significantly associated with T. vaginalis among pregnant women. 
Conclusions: T. vaginalis is prevalent among pregnant women seeking health care in Sana’a, particularly housewives, illiterate women and those coming from rural areas. Presence of vaginal discharge with unpleasant odor and itching are associated with a higher risk of infection among symptomatic women. Further large-scale studies are required to determine the prevalence and risk factors among women of the reproductive age in Yemen.


Introduction
Sexually transmitted diseases (STDs) pose a major public health problem in both developed and developing countries. Trichomoniasis, which is caused by the protozoan parasite Trichomonas vaginalis, is one of the most common non-viral STDs in the world (1, 2). In 2008, 276.4 million cases infected with STDs were reported in the world, with about 90.0% of infected cases having occurred among people living in resource-limited settings (3). T. vaginalis infects the lower genital tract of females as well as urethra and prostate of males. The common way of infection is the direct transmission from person to person through sexual contact, but the infection can occur through toilet seats, moist towels, contaminated douche nozzles, specula or swimming pool water (4,5).
Trichomoniasis may be asymptomatic and, therefore, infected individuals do not know that they are harboring the parasite. In fact, most males and about half of infected females infected with the parasite show no symptoms themselves but can transmit it to others. Asymptomatic trichomoniasis is usually characterized by vaginitis, urethritis, vaginal discharge, vulvar itching, irritation, premature birth and delivery of lowbirth-weight infants, postpartum endometritis, stillbirth and death (6). It may also increase the acquisition and transmission risk of human immunodeficiency virus (HIV) and herpes simplex virus type 2 infections (1, 2, 7-9).
Trichomoniasis can be difficult to diagnose because infected individuals, particularly males, are usually asymptomatic or mildly symptomatic carriers (10). Generally, examination of wet mounts of discharges and their cultivation are the most widely used methods for the diagnosis of T. vaginalis (11,12).
Trichomoniasis is one of the most neglected diseases in Yemen, where there is the knowledge of the population about its transmission, prevention and control is still poor. In addition, there is a lack of the estimates of the infection rate and its possible risk factors. It is noteworthy that Yemen is one of lowest-income and least-developed countries in the world. Besides the neglect of preventable infectious diseases, the country has been placed in the bottom of human development category according to the latest Human Development Report issued in 2015 (3). Moreover, the World Bank ranks Yemen as one of the poorest countries, where about two-thirds of Yemeni people live in rural areas (3). Therefore, the aim of the present study was to determine the prevalence of T. vaginalis infection and associated risk factors among pregnant women seeking primary health care in Sana'a city

Study design, population and setting
This cross-sectional study was conducted among pregnant women seeking routine health care in private clinics or governmental health care centers in Sana'a city in the period from October 2014 to June 2015. Sana'a city, the capital of Yemen, is located in the northern part of Yemen at the geographic coordinates of 15° 20' 54''N and 44° 12' 23 E. Inclusion criteria were pregnant women in any trimester, who were aged between 17 and 47 years old and referred to private obstetrics clinics or governmental primary health care centers as a result of having genitourinary tract infections.

Sample size calculation
The sample size was calculated by Epi Info™, version 7.1.3 (Centers for Disease Control and Prevention, Atlanta, USA), using the following parameters: population size of 2 million, 5.0% con-fidence limits, 95.0% confidence level and 1.0 design effect. The frequency of outcome was considered as 20.0%. Accordingly, the minimum sample size required was 246 women. However, 287 women were included after adding a rate of 15.0% of the calculated sample size was added to overcome a possible non-response, unusable data or other limitations.

Data collection
Data on the sociodemographic and clinical characteristics as well as possible risk factors predisposing to T. vaginalis infection were collected using a predesigned questionnaire by trained researchers. Physicians took samples of vaginal discharges from pregnant women using sterile non-absorbent cotton swabs. Specimens were then labeled with the patient's name and identification number, date and place of collection.

Wet mount examination
Specimen wet saline mounts were immediately examined for motile T. vaginalis trophozoites under the 10X and 40X objectives of a light microscope by an experienced laboratory microscopist.

Statistical analysis
Data were analyzed by IBM SPSS Statistics, version 21.0 (IBM Inc., Armonk, NY, USA). Differences and associations between categorical variables were tested using Pearson's chi-square test and considered statistically significant at Pvalues <0.05. In addition, the odds ratios (ORs) and their corresponding 95 % confidence interval (CI) were also calculated. Multivariable analysis using a logistic regression model was also performed to identify independent predictors of T. vaginalis infection among pregnant women.

Characteristics of the study population
The mean age of the patients was 29.1 ± 7.2 years (range:

Prevalence of T. vaginalis infection among pregnant women
The overall prevalence of T. vaginalis infection among pregnant women was 11.1% (32/287).

Discussion
Up to the best of our knowledge, the present study was the first to explore the prevalence and risk factors associated with T. vaginalis among pregnant women in Sana'a. Light microscopy reveals T. vaginalis prevalence of 11.1% among pregnant women attending to health care facilities in Sana'a. This finding is comparable to those recently reported from Brazil among rural women seeking primary health care (10.5%) and among female patients from gynecology departments (9.0%) (10,13). In addition, it is consistent with those reported among Tanzanian women and their male partners (10.7%) in a communitybased study and among socially-marginalized Peruvian females (9.1%) (1, 14).
In the present study, infection rate was found to increase with the age, where pregnant women aged between 26 and 47 years old showed the highest infection rate. This finding agrees with those reported in previous studies from Iran (15,16). This could be partly attributed to biologic changes in older women as one of the predisposing factors to the parasite growth or longer duration of infectiousness and resistance to treatment.
The higher proportion of T. vaginalis among rural than urban pregnant women (18.5% vs. 9.0%, respectively) is consistent with several studies from different countries, including Mozambique (17), Palestine (18), Argentina (19) and the United States (20). The variation in T. vaginalis prevalence rates among different societies could be attributed to a number of factors, including sexual hygiene, sociodemographic characteristics and diagnostic tests used.
Although limited by the nature of discharge examination by light microscopy that might miss light infections, the present study could be considered a preliminary one exploring the status of T. vaginalis infection among Yemeni pregnant women. Therefore, further large-scale communi-ty-based studies are recommended using more advanced diagnostic procedures such as the cultivation of the parasite and its detection by molecular techniques.

Conclusions
The present study reveals a low prevalence of T. vaginalis as detected by light microscopy among Yemeni pregnant women seeking health care, which is comparable to several other developing countries. Age and literacy status of pregnant women are independent predictors of infection, with a higher risk of contracting infection among older and illiterate women. Of clinical manifestations of symptomatic infections, presence of vaginal discharge, unpleasant odor and vaginal itching are associated with the presence T. vaginalis infection among Yemeni pregnant women.