Sexually transmitted infections (STIs) is a global health problem with increased risk and morbidities during pregnancy. This study investigated the magnitude of viral STIs among pregnant women from three rural hospitals/clinics providing antenatal care in Mwanza region, Tanzania.
Between February and May 2018, a total of 499 pregnant women were enrolled and tested for Human immunodeficiency virus (HIV), Herpes simplex virus-2 (HSV-2), Hepatitis B virus (HBV) and Hepatitis C virus (HCV) using rapid immunochromatographic tests and for syphilis using non-treponemal and treponemal antibody test.
The median age of enrolled women was 25 (IQR: 22–31) years. Seventy eight (15.6, 95% CI: 12–18) of women tested had at least one sexually transmitted viral infection. Specific prevalence of HIV, HBV, HCV, HSV-2 IgG and HSV-2 IgM were found to be 25(5.0%), 29(5.8%), 2(0.4%), 188(37.7%) and 24(4.8%), respectively. The odds of having viral infection was significantly high among women with positive T. pallidum serostatus (adjusted odd ratio (aOR): 3.24, 95%CI; 1.2–85). By multivariable logistic regression analysis, history of STIs predicted HSV-2 IgM seropositivity (aOR: 3.70, 95%CI: 1.43–9.62) while parity (aOR: 1.23, 95%CI: 1.04–1.46) predicted HBV infection and syphilis positive results (aOR: 8.63, 95%CI: 2.81–26.45) predicted HIV infection.
A significant proportion of pregnant women in rural areas of Mwanza region has at least one sexually transmitted viral infection which is independently predicted by positive T. pallidum serostatus. The strengthening and expansion of ANC screening package to include screening of STIs will ultimately reduce the viral STIs among pregnant women hence reduce associated morbidities and mortalities.
Sexually transmitted infections (STI) particularly those caused by viruses have been associated with a number of adverse pregnancy outcomes including stillbirth, spontaneous abortion, preterm births, prematurity, postpartum endometritis and low birth weight among other various long term sequelae in surviving neonates [1, 2]. Herpes simplex virus type 2 (HSV-2) is the main causative agent of genital ulcer diseases worldwide . It can be transmitted vertically from mother to the fetus and it is highly prevalent in the sub-Saharan Africa whereby it has been found to cause severe illness to the neonates [4–7].
On the other side, a previous study reported that nearly 90% of pregnant women living with HIV in the world are from sub-Saharan Africa [8, 9]. Challenges associated with effective prevention of mother-to-child transmission of HIV (PMTCT) include adherence and failure in identifying HIV-infected mothers , making HIV still a problem in these countries. Regarding viral hepatitis, Hepatitis B virus (HBV) and hepatitis C viruses (HCV) are major public health concern worldwide with high prevalence in the sub-Saharan Africa and Asia [10, 11]. It is estimated that, over 1 million deaths related to chronic liver disease are due to HBV . Most of individuals in endemic areas are infected vertically or during childhood . Similarly, HCV infection are common in many countries worldwide . The World Health Organization (WHO) estimates that 3% of the world’s populations are chronically infected with HCV with high prevalence reported in the sub-Saharan Africa [13, 14].
The current practice regarding antenatal screening in Tanzania includes routine screening of HIV and T. pallidum infections while the care for other STIs like HSV-2, HBV and HCV mostly rely on symptoms. Nevertheless, in many developing countries particularly in rural settings, it is uncommon to visit health facilities unless having signs and symptoms of disease and most of these STIs are asymptomatic . Due to the current situation regarding antenatal screening of these infections in Tanzania, data regarding the magnitude of these infections among pregnant women in rural setting are scarce. Lack of these data hinders introduction of the appropriate strategies to prevent these infections especially in rural areas. This study was conducted to establish the magnitude of sexually transmitted viral infections among pregnant women in Tanzania. The data might help to come up with recommendations on the current screening protocol and control strategies.
Study design and duration
A cross sectional hospital based study involving 499 pregnant women attending three rural antenatal clinics (Magu, Karume and Sengerema) in Mwanza region was conducted between February and May 2018.
The study was conducted in Sengerema, Ilemela and Magu districts in Mwanza region, Tanzania. (http://www.jgid.org/viewimage.asp?img=JGlobalInfectDis_2010_2_3_216_68530_u3.jpg). Mwanza is located in the North-Western zone of Tanzania, with a population of 2,772,509 . Sengerema Designated Ditrict hospital (DDH) has a capacity of 320 beds and attends approximately 30–40 pregnant women daily at its antenatal clinic , it is located 60 km from Mwanza city. Magu District Hospital (MDH) is 60 km from Mwanza city and has capacity of 200 beds and attends approximately 30–40 pregnant women daily in the antenatal clinic. Karume Health Centre (KHC) is located in Ilemela district 20 km from Mwanza city and serves about 20–30 pregnant women daily. The antenal atendance in Mwanza region in 2018 is about 73% with 83% delivery in health facilities (www.dhis.moh.go.tz).
Study population and selection criteria
All pregnant women at different ages and gestation ages attending at KHC, Sengerema DDH and MDH antenatal clinics were included in the study after obtaining informed consent.
Sample size estimation and sampling technique
The sample was calculated by Kish Leslie formula for observational study  using the prevalence of 50% to get the minimum sample size of 384 participants, however, 499 pregnant women were enrolled. Purposive sampling was used to select the study areas and the study participants were enrolled serially as they come to a clinic until the desired sample size of that clinic was reached. The sample size from each clinic was calculated based on the proportion of women attending specific clinic daily.
Data and samples collection
A pre-tested structured data collection tool which comprised both open and close ended questions was used to collect required data (Additional file 1). Data collected included demographic and clinical data such signs and symptoms of STIs. Individual face to face interview was used to obtain these data from a study participant. Antenatal cards were reviewed to get information such as antenatal visits profile, gestation age and important antenatal investigations such as syphilis and HIV testing.
The first trimester was defined as ≤13 weeks, second trimester 13 - ≤ 26 weeks and third trimester more than 26 weeks of gestation. Data were collected by nurses in case the patient required special attention was reviewed by doctors present in the respective hospital or the OB/GY resident. About 4-5mls of venous blood sample was collected from each of enrolled participant and placed in plain vacutainer tubes (Becton, Dickinson and Company, USA). Samples were transported to the Catholic University of Health and allied sciences for processing. Sera were extracted and stored in cryovials at -40C until analysis.
Samples were tested as per national HIV diagnosis algorithm using SD Bioline and Unigold as previously, described  to establish HIV serostatus. Detection of HSV-2 virus specific IgM and IgG antibodies was done by using rapid immunochromatographic test as per manufacturer’s instructions (Exact Diagnostic Devices -USA). The test has a sensitivity of 95% and specificity of 94.7%. Hepatitis B surface antigen HBsAg (Accu-Tell, Beijing, China) and HCV antibodies were tested using rapid immunochromatography tests as per manufacturer’s instructions (ACON laboratories, Inc., CA92121, USA). Syphilis was detected using non-treponemal test (Standard diagnostics-Inc, Korea) and all positive samples were confirmed using Treponema pallidum Hemagglutination test (Chronolab systems, Barcelona, Spain).
Data collected were entered into a computer using Microsoft Office Excel 2007 and analyzed by using STATA version 13 (STATA Corp LP, USA). In the present study any patient with history of vaginal discharge or genital ulcer or clinically treated as case of STIs in the past was considered to have history of STIs. Presence of at least one viral infections was defined as being positive to HSV2 IgM antibodies or positive HIV status or positive HBsAg or positive HCV antibodies. Categorical variables (marital status, education level, occupation, history of STIs, use of condoms etc.) were summarized as proportions and were analyzed using the Pearson’s Chi-square test to observe the significant differences in distribution of viral infections among various groups like age, education levels etc. Continuous variables (age, gestation age, parity, number of sexual partners etc.) were summarized as median with inter-quartile range. Univariable and multivariable logistic regression model was used to determine the factors associated with HSV-2, HIV and HBV positivity. Variables with p-value less than 0.2 on univariable regression model were subjected into the backward multivariable logistic regression analysis adjusted by age. Odds ratio and 95% confidence interval were noted. Variables with p-value of less than 0.05 were considered statistically significant.
Sociodemographic, relationship and sexual history characteristics of 499 pregnant women attending ANCs in Mwanza – rural Tanzania
A total of 499 pregnant women with the median age of 25 (IQR: 22–31) years were enrolled. Of these women, 98, 200 and 201 were from Karume clinic (Ilemela), Magu district hospital and Sengerema district hospital, respectively. Most of the participants were in the second 257(49.5%) and third 222(46.5%) trimesters with the median gestation age of 25(IQR: 20–32) weeks. Approximately two-thirds (63.9%) had completed primary school while (17.8%) of the women had never attended any formal school. The majority of women 464 (93%) were married and more than half 277 (55.6%) were peasants. Approximately more than half 266 (53.3%) reported having more than one sexual partner in lifetime and less than one-fourth of women 109 (21.8%) knew that their partner had other partner(s) outside of their relationship. Of the 499 participants, 20 (4%) were T. pallidum (syphilis) seropositive (Table 1).
Sociodemographic, relationship, sexual characteristics and clinical signs among 499 pregnant women attending ANCs in Mwanza-rural Tanzania
|Characteristics||Frequency/Median (IQR)||Percentages (%)|
|Age (years)||25 [IQR: 22–25]|
|Gestation age (weeks)||25[IQR:20–32]|
|Age of 1st sexual intercourse||17[IQR16–18]|
|Number of sex partners||2[IQR1–4]|
|Partner has other women outside relationship|
|More than two Sexual partners|
|H/Lower abdominal Pain|
History of STIs symptoms and risk behaviour among 499 pregnant women attending ANCs in rural areas of Mwanza region Tanzania
Among 499 pregnant women enrolled, 92 (18.4%) were found to have history of STIs and almost half of the women 249 (49.9%) reported a history of lower abdominal pain. A total of 174 (34.9%), 109 (21.8%) and 28 (5.6%) women reported history of dysuria, dyspareunia and genital ulcers, respectively. In addition, more than three quarters 388(77.8%) of women reported no history of condom use during sex (Table (Table11).
Prevalence of HSV-2, HIV, HBV and HCV among 499 pregnant women attending ANCs in Mwanza- rural Tanzania
Seventy eight (15.6, 95% CI: 12–18) of women tested, had at least one sexually transmitted viral infection. A total of 188(37.7, 95% CI: 33–41) were found to be HSV-2 IgG seropositive while 24 (4.8 95% CI: 2–6) wereHSV-2 IgM seropositive. On Wilcoxon Ranksum (Man Whitney) test there was no significant difference in age between those who were HSV-2 IgG seropositive and HSV-2 IgG seronegative (26, IQR: 21–31 vs. 25, IQR: 22–31, p = 0.455). However, the HSV-2 IgG seroprevalence was significantly high among women aged below 20 years compared to women aged above 20 years [45 (47.4%) vs. 143(35.4), p = 0.030]. In addition, 8 women who were HSV-2 IgG seropositive were found to have genital ulcer whereby 4 of them were T. pallidum (syphilis) seropositive. Regarding HSV-2 IgM seropositivity, there was no significant difference in age between IgM seropositive women and seronegative women (25, IQR: 22–28 vs. 26, IQR: 21–31, p = 0.699).
The prevalence of HBV was found to be 29(5.8, 95% CI: 3.7–7.6). The median age of HBV positive women was 30 (IQR: 21–33) years compared to HBV negative women 25 (IQR: 22–31), p = 0.082. The seroprevalence of HIV was 25(5.0, 95% CI: 3.0–6.9). The median age of HIV seropositive women was significantly high compared to their counterparts [28 (IQR: 25–32) vs. 25 (IQR: 21–31), p = 0.032]. Overall, seroprevalence of HCV were found to be 2(0.4, 95% CI: 0.2–0.5) (Fig. 1). These two patients were HIV, HBV, HSV IgM and syphilis negative but were positive for HSV IgG antibodies.
Prevalence of sexually transmitted viral infections among 499(N) pregnant women in rural areas of Mwanza region. Letter “n” refers to positive samples for each virus
Factors associated with HSV-2 IgG and HSV-2 IgM seropositivity among 499 pregnant women attending ANCs in Mwanza- rural Tanzania
Regarding HSV-2 IgG seropositivity, on univariable analysis, only age at first sex (aOR: 0.917, 95%CI: 0.84–0.99, p = 0.028) was found to be associated with IgG seropositivity. However, the history of STIs (aOR: 1.45, 95%CI: 0.99–2.12, p = 0.053) had borderline significance on multivariable analysis (Table 2). In addition, on univariable analysis, history of STIs (OR: 3.47, 95% CI: 1.36–8.91, p = 0.009) was significantly associated with specific HSV-2 IgM seropositivity and remained significant on multivariable logistic regression analysis (aOR: 3.70, 95% CI: 1.43–9.62, p = 0.007) (Table 3).
Univariable and multivariable logistic regression analysis of the factors associated with specific HSV-2 IgG seropositivity among 499 pregnant women attending ANC’s in Mwanza-rural Tanzania
|Univariable||P – value||Multivariable||P – value|
|Age||26 [IQR 21–31]||0.99[0.97–1.02]||0.678||1.00[0.97–1.03]||0.895|
|Parity||1.5 [IQR 0–3]||0.98 [1.089–1.076]||0.676|
|Gestational age||24 [IQR 20–32]||0.99 [0.97–1.02]||0.562|
|Number sexual of partners||2 [IQR 1–4]||1.03 [0.98–1.08]||0.315|
|*Age at first sex||17[IQR:15–18]||0.917[0.84–0.99]||0.028||0.92[0.85–1.00]||0.056|
|House wife (79)||33(41.77)||1.52[0.86–2.67]||0.153||1.44[0.80–2.59]||0.221|
|Secondary (91)||28 (30.77)||ref|
|Never attended (89)||30(33.71)||1.44[0.61–2.14]||0.673|
|Not married (35)||17(48.57)||1.62[0.81–3.22]||0.171|
|*History of genital ulcer|
|Present (28)||8 (28.57)||0.65 [0.28–1.49]||0.309|
|*History of STIs|
|Yes (238)||98 (41.18)||1.33 [0.93–1.91]||0.124||1.45[0.88–2.12]||0.053|
|Positive (25)||6 (24%)||0.51[0.19–1.29]||0.155||0.55[0.21–1.42]||0.218|