Review Article - Biomedical Research (2018) Volume 29, Issue 12
Omorodion Oriri Asemota*
Industrial Safety and Environmental Technology Department, Petroleum Training Institute, Effurun, Nigeria
Accepted date: April 18, 2018
Sexually Transmitted Parasitic Diseases (STPDs) are infectious diseases that are transmitted via unprotected sex which could potentially predispose men and women to different reproductive health issues. The data presented in this report shows that, trichomoniasis caused by Trichomonas vaginalis (TV) remain the only reported sexually-transmitted parasitic disease in Nigeria. Also, of the 36 states in the country, only 26 states including the Federal Capital Territory (FCT), Abuja have partly evaluated the prevalence of the disease. Furthermore, the prevalence data on the burden of TV infections in Nigeria in form of Years Lived with Disability (YLD), the distribution of the infection in the six geopolitical zones and the prevalence over the years are presented. Notably, YLD for TV infection was highest in the South-South; while the factors possibly impacting on the burden of TV in Nigeria are highlighted.
Sexually transmitted parasitic diseases (STPDs), Trichomoniasis, Nigeria
Sexually Transmitted Diseases (STDs) being transmitted by sex through different routes are amongst the commonest communicable diseases globally with more than 1 million new infection daily . The burden of STDs largely occurs in developing countries ; with the most vulnerable, disproportionately affected by other health and socialeconomic issues. In developing countries, STDs are among the leading causes of Disability-Adjusted Life Years (DALYs) lost for women of reproductive age .
Parasitic STDs include trichomoniasis, amoebiosis and giardiasis [4,5]. Infection with Sexually Transmitted Parasitic Diseases (STPDs) has resulted in debilitation or anatomic deformities that make sex impossible as a result of direct damage to the male and female reproductive organs including impairing fertility via the inhibition of gamete production .
Trichomonas vaginalis is the most common STPDs in Nigeria; and studies on STPDs remain relatively scanty [7-10]. In addition, knowledge about T. vaginalis and trichomoniasis is hugely lacking; and this identified gap may have impacted on the burden of infection.
This review article thus present prevalence data for Nigeria by states; and highlight the gaps in information regarding various aspects of the disease. Further, the implication of the relatively lack of awareness about T. vaginalis infection were noted and discussed.
In Nigeria, amongst the vast array of endemic parasitic diseases, only trichomoniasis is sexually transmitted. There are other parasites that could be transmitted via oral-anal and oralgenital routes and as such can elicit other forms of sexually transmitted diseases. Of the 36 states and Abuja, T. vaginalis studies could only be accessed for twenty-six (26) states (Table 1). These studies spanned through the different geo-political zones (South-East, South-South, South-West, North-West, North-East and North-North) of the country. In spite of this, there is still limited/lack of literature on the prevalence of T. vaginalis infection in some other states. From available data, the prevalence across the country ranged between 0-51.8%. Majority of these studies were carried out on pregnant women in the different geo-political zones, and samples were mostly vaginal swab (Table 1).
|Zone||State||Participants||Number tested||Prevalence (%)||Sample (s) used||References|
|Anambra/Enugu||Male adolescents||361||25.2||Urine, urethral smears, semen|||
|Ebonyi||HIV-seropositive women||250||24.4||Urine, HVS|||
|Anambra||Women between 20 years and above||200||17.5||HVS|||
|Ebonyi||Pregnant women||688||12.9||Vaginal swab|||
|Ebonyi||Single and married pregnant women||1025||12.3||Vaginal swab|||
|Imo||Female/adult out patients||1241||10.2||HVS|||
|Imo||Males and females||5883||1.3||US|||
|Bayelsa||Females patients with vaginal complaints||1240||6.5||HVS, ECS|||
|Rivers||Women attending antenatal, gynaecology, family planning and sexually transmitted disease clinics||220||4.5||HVS|||
|Rivers||Women from urban and sub-urban areas||1431||0.63||HVS|||
|Edo||Adolescent girls in secondary schools||272||9.2||HVS|||
|Akwa-Ibom||HIV-seropositive people||150||16.2||HVS, urine|||
|Akwa-Ibom||Pregnant women||560||44.5||HVS, ECS|||
|Delta||Women at Effurun||100||6||HVS|||
|Delta||Secondary school girls, teachers, undergraduates and petty traders||240||22.5||Urine, HVS|||
||Ogun||HIV-infected and non-infected women||100||5||Urine, HVS|||
|Osun||Female patients||310||8.1||HVS, ECS, US|||
|Ogun||Pregnant women||200||20||HVS, Urine|||
|Ibadan||ARFH attendees||200||1.5||Blood, HVS, ECS|||
|Oyo||Pregnany ante-natal patients||150||25.3||HVS|||
|Ondo||Seropositive and sero negative pregnant women||240||50 and 22||HVS|||
|Ondo||Seropositive and sero negative males and females||100||0 and 6||Urine and HVS|||
|Ibadan||Sexual partners of women with confirmed diagnosis of TV||44||45.5||Urethral swap|||
|Ogun||Female students Babkock University||200||12.5||HVS|||
|Lagos||Patients with virginal discharge||200||74.5||HVS|||
|Ogun||University male female students in redemption camp||60||1.67 and 3.3||urine|||
|North-West||Kaduna||Pregnant women||120||19.2||HVS, Blood|||
|Kebbi||Female patients||220||4.1||Urine, HVS|||
|Kano||Females with abnormal vaginal discharges||2000||1.5||ECS, HVS|||
|Kaduna||Females living in Palladan||150||13.67||HVS|||
|Kaduna||HIV-seropositive antenatal clients||102||5.9||HVS|||
|Adamawa||Health males, females, antenatal women, and sick males and females without any history of Trichomoniasis||1520||2.6||Blood and genital swab|||
|North-Central||Plateau||HIV-1 infected women||168||51.8||HVS|||
|Nasarawa||Pregnant women||960||7.5||Urine, HVS|||
|Nasarawa||Female patients||200||8.5||Vaginal discharge|||
|Kwara||Pregnant women||250||20||HVS, Urine|||
|FCT, Abuja||Primary school pupils||402||3.73||Urine, stool|||
|Kwara||HIV-seropositive antenatal clients||160||5.6||ECS, HVS|||
|Benue||Females patients||200||10.5||HVS, Urine|||
|Benue||Male and female patients||400||12||Urine|||
|Nasarawa||Male and female patients||1050||15.71||Urine, HVS|||
|FCT, Abuja||Male and female patients||286||15||Blood, ECS, HVS, Urine, Urethal swabs, Urethal discharge|||
|Nasarawa||Female students of Bingham University||200||4.5||Low vaginal swabs|||
|Plateau||HIV positive and negative patients||700||17||HVS|||
Table 1. Prevalence of trichomoniasis across zones and states.
The prevalence of T. vaginalis infection is relatively higher in sexually active women . In males, T. vaginalis infection is generally trivial or asymptomatic. Asymptomatic carriers can serve as vectors for the disease, making it important to treat male partners. The parasite resides in the female’s lower genital tract and the male urethra and prostate.
Reports from Nigeria suggest that, trichomoniasis could be higher in urban areas than in the rural communities [72,73]. For example, in a study carried out by , a higher prevalence of T. vaginalis was documented for subjects that resided in urban areas (57.70%) than those that lived in rural communities (39.16%). Also, prevalence was highest amongst the sexually active group of age 11-45 years old .
Amongst pregnant women, T. vaginalis is generally high [9,39]. In Zaria, pregnant women between ages 16 to 25 were reported to be T. vaginalis positive with prevalence of 53.57% . In Lagos, South-West, Nigeria, T. vaginalis prevalence of 1.8% was recorded for pregnant women between 21 to 30 years old. Similarly, in Abeokuta, South-West Nigeria, pregnant women between the age 20 and 30 had prevalence of 21.3%. Meanwhile in Anambra, South-East Nigeria, nonpregnant women had higher rate of infection (17.8%) than pregnant ones (16.7%) . Furthermore, a study in Maiduguri showed a high rate of 20.8% infection among non-pregnant women .
In relation to marital status, a prevalence of 2.9% was recorded among Lagos married women compared to 0.4% prevalence in unmarried women . Amadi and Nwagbo  reported 19.72% for single women in Abia, South-East, Nigeria with 21.6% and 11% among Abeokuta and Maiduguri married women respectively [8,38].
Data have shown that HIV could escalate infection with T. vaginalis [61,75,76]. Isiaka-Lawal et al.  observed that the prevalence of trichomoniasis was higher in HIV infected women than their uninfected counterparts in north-central Nigeria, while in Lagos, a prevalence of 35.8% were noted in HIV positives .
Available data had revealed an increased risk of T. vaginalis infection in persons with poor personal hygiene and low socioeconomic status . Levels of education have been linked to prevalence rate. For instance, non-formal educated women had an infection rate of 22.3% while tertiary educated women had only 1.0% . Also, Usanga et al.  reported that women with primary school education had 6.4% prevalence rate. In addition, poverty, unemployment, violence against women and children [17,24], and young age could raise the risk associated with acquiring T. vaginalis infection [63,79].
Diagnostic methods available for trichomoniasis are wet mount preparation, staining methods, culture in laboratory medium, and molecular methods. Historically, detection of the parasite is made possible by examination of urine and High Vaginal Swab (HVS) in a drop of saline or trichomonas diluents for the characteristic wobbling and rotating motion. Amadi and Nwagbo  reported that either urine sample or vaginal swab is insufficient for proper diagnosis of T. vaginalis infection and have suggested that for better results both urine and vaginal swab should be used. Diagnosis of trichomoniasis has relied mostly on wet mount demonstration and staining of the parasite in the laboratory with success rate of between 20 and 80% . A combination of cultural method with microscopic wet mount demonstration is now the acceptable procedure for effective diagnosis .
New molecular diagnostic tests with improved sensitivity have been developed in response to the increasing recognition by stakeholders of the importance of this wide-spread STI. Thus the detection of T. vaginalis, including rapid antigen detection and nucleic acid amplification tests, has significantly improved the quality of diagnostics for trichomoniasis, particularly in women . In America, Guillermo et al.  reported 97% sensitivity for molecular amplification diagnostic methods, as against 70 and 36% sensitivities for culture and wet preparations respectively. Also, studies of genetic typing of the parasites have been reported to be more sensitive than other methods [84,85]. However, in Nigeria there is no report of the application molecular diagnosis tools on T. vaginalis infection, which may influence the prevalence data as presently reported from less reliable tests.
Evaluation of the disease burden is essential in determining the cost-effectiveness of control so as to ensure that control programmes are focused appropriately. Disability Adjusted Life Year (DALYs) is the trending metric measurement to assess disease burden . DALYs include years of life lost due to mortality (YLLs) and years lived with disability (YLDs). Most T. vaginalis survey is mainly on women, but reports of infection burden measured in DALYs are unavailable. Here we have estimated value of YLD based on available prevalence data and morbidity of the infection . YLD due to TV in this review was estimated using the formula below .
YLD=P × DW
Where, P=number of prevalent cases, DW=Disability Weight.
Here, prevalence was used rather than incidence , because in Nigeria, surveys are widely reported in prevalence (Table 2). DW (0.027) of infection which is represented on a scale of 0-1 (0=perfect health; 1=death), was adopted . YLDs due to TV, according to the geopolitical zones are shown in Table 2. This review shows that the YLD from T. vaginalis prevalence data in Nigeria ranged from 21 to 63 with the highest and least disease burden recorded in South-South and North-West respectively.
|Region||Mean ± SD (%)||YLD /10 000|
|South-East||16.12 ± 9.9||44|
|South-South||23.3 ± 16.3||63|
|South-West||17.3 ± 20.2||47|
|North-West||7.6 ± 7.3||21|
|North-East||11.4 ± 9.0||31|
|North-Central||12.5 ± 12.4||34|
Table 2. T. vaginalis mean prevalence and estimated YLD according to geopolitical zones (1984-2017).
Control and elimination may depend largely on extensive proper sex education, especially for the adolescent and youths [7,8]. Also suggested are adequate treatment of both spouses, implementation of effective screening programmes and treatment at no cost . For improved health, adequate personal hygiene, avoidance of promiscuity, improved education of women on safe sex and the need to know partners’ STI status are advocated [14,77]. It is recommended that routine STIs screening in sexually active patients especially among the young and singles should be incorporated into hospital care . This is needed to prevent transmission of the parasite, because some infected women and most infected men show no signs of the disease like liquid discharge from the vagina or penis, irritation while urinating and genital itching. So this YLD information is vital to focusing efforts on getting women tested and treated Based on the results from this study, trichomoniasis control in Nigeria should especially be of high priority in the South-South.
Data available in this review have clearly outlined the prevalence of trichomoniasis in Nigeria, with the South-South having the highest disease burden. The dearth of information and very poor awareness of this STDs among the populace may have impacted on the burden of infection. Thus, increased awareness on the parasite and the disease at all levels is highly recommended. Also, ensuring that health workers include T. vaginalis as part of a routine procedure in the course of screening for STDs is thus advocated. Furthermore, providing better sensitive methods for diagnosis is the way to go as this would ensure near-accurate information on the prevalence of the disease in any given area in Nigeria.