https://orcid.org/0000-0002-5188-0568
Figures
Abstract
There is a scarcity of studies on the prevalence of Trichomonas vaginalis (TV) in indigenous populations of Brazil. We conducted a cross-sectional study between January and December 2018, on indigenous women living nearby an urban center of the Midwest region of Brazil and determined the prevalence of TV. Factors associated with TV infection and a comparison of molecular and direct microscopy diagnoses were determined. 241 indigenous women aged above 18 years participated in the study. Cervical and vaginal brush samples were collected to diagnose TV through polymerase chain reaction (PCR). Direct microscopy for detection of TV, and cellular changes was performed. A sociodemographic and behavioral questionnaire was applied at the beginning of the study. All the data were analyzed using Statistical Package for the Social Sciences. The result obtained showed that 27.8% [95% CI: 22.2–33.9] were positive for TV on PCR, while 7.41% [95% CI: 4.1–11] showed positive on direct microscopy. Direct microcopy also found 21 (8.71%) and 8 (3.31%) women infected with Gardnerella vaginalis and Candida albicans, respectively. In addition, 10 women presented atypical squamous cells of unknown significance and 14 lesions suggestive of HPV. Single women, under the age of 30 and who do not use condoms, were found to have a greater chance of getting TV infection. The high prevalence TV found in this population is comparable to highly vulnerable populations, as prisoners, sex workers and women in regions with low socioeconomic levels, moreover, seems to be an underdiagnosis of this infection. Therefore, a routine test program, as well as a review of the diagnostic method used, is encouraged for proper management.
Citation: Barbosa MdS, Andrade de Souza IB, Schnaufer ECdS, Silva LFd, Maymone Gonçalves CC, Simionatto S, et al. (2020) Prevalence and factors associated with Trichomonas vaginalis infection in indigenous Brazilian women. PLoS ONE 15(10): e0240323. https://doi.org/10.1371/journal.pone.0240323
Editor: Catherine E. Oldenburg, University of California, UNITED STATES
Received: June 7, 2020; Accepted: September 23, 2020; Published: October 16, 2020
Copyright: © 2020 Barbosa et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: All relevant data are within the paper and its Supporting Information files.
Funding: This work was partially supported by the National Council for Scientific and Technological Development (CNPq grant 440245/2018-4), Support Foundation for the Development of Education, Science and Technology of the State of Mato Grosso do Sul (FUNDECT grants 092/2015 and 041/2017), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior- Brazil (CAPES, Finance code 001), Government of the State of Mato Grosso do Sul, Health Department of the state of Mato Grosso do Sul and Proex/Universidade Federal da Grande Dourados (UFGD). The sponsors had no role in the collection, analysis, and interpretation of data or the writing of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
Introduction
Developing countries are mainly threatened by infectious diseases of the reproductive tract and sexually transmitted infections (STIs), which are considered a major public health problem. The main and most prevalent STIs described in the literature are caused by Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis (TV), and Treponema pallidum [1, 2]. These pathogens can cause acute urogenital conditions, such as cervicitis, urethritis, vaginitis, and genital ulceration [1, 2]. Trichomoniasis, caused by TV, is the non-viral STI most common in the world [3, 4]. It is a flagellated protozoan affecting both sexes, and women are more affected comparatively. Approximately 85% of women are asymptomatic carriers of TV. However, once the symptoms arise, it affects the region of the vulva, vagina, and cervix, being associated with pelvic inflammation, neoplasms, premature birth, and the promotion of HIV infection [4].
The diagnosis of TV in the public health network is basically performed through direct microscopy of a sample obtained in the Pap smear test. Although the Pap smear has specificity for T. vaginalis, there are sensitivity limitations that prevent the use of this technique for the diagnosis of infection [3, 5]. The main focus of this technique is on the search for cellular changes such as atypical granular cells and squamous lesions, other findings such as Gardnerella vaginallis infection or Candida albicans, end up being in the background, which can also be related with problems in the female reproductive tract, especially the imbalance of bacterial flora, increasing the risk of infection by other STIs [6–8].
In countries like Brazil, trichomoniasis remains unreported, making it difficult to measure the extent of the disease [9]. In 2012, the World Health Organization (WHO) reported about 357 million new cases of non-viral STIs worldwide, of which 142 million were caused by TV [4]. Studies conducted in Brazil have reported TV infection prevalence rates between 3.7% and 30% [4, 10]. Many populations related to low socioeconomic conditions, along with other factors such as age, gender, and sexual choice, have shown above-average prevalence rates for STIs [4, 11]. T. vaginalis mainly affects the poorest sections of the population and people in vulnerable situations [12].
An estimated indigenous population of 817 thousand people from 305 different ethnicities lives in Brazil. This population is divided into 5,614 villages, occupying approximately 12.6% of the Brazilian territory, most of them living in lower socioeconomic conditions than the rest of the country [13–15]. Although Brazil has specific legislation for indigenous health, only little is applied. Research on this population is still primarily related to sociocultural issues, and very little has been published on health issues [14]. In this context, the prevalence of the TV was determined in indigenous women living in the Midwest region of Brazil. We determined the factors associated with TV infectious as well as performed a comparison of molecular and direct microscopy diagnoses used in primary care.
Methods
Type of study and sample size calculation
A cross-sectional study was conducted to determine the prevalence of TV in indigenous women from two Indigenous Reserves of Dourados—Mato Grosso do Sul, in the Midwest region of Brazil. We obtained approval from the National Research Ethics Commission (number 2.000.496) for this study. Based on the population of 8,000 women aged above 18 years, considering an average prevalence of T. vaginallis of 15% (4–27%) and a 5% margin of error, a minimal sample of 192 women was estimated [12].
Study participants and epidemiological questionnaire
The study was performed between January 2018 and December 2018. A total of 241 women, over the age of 18, agreed to participate in the study and signed an informed consent form. Data and samples were obtained during their visit to the Basic Health Units of the two indigenous reserves evaluated: Bororó and Jaguapiru village, where Guarani (Kaiowá and Nhandeva) and Terena ethnicities predominate.
A questionnaire addressing demographic was given to the participants contemplating the following variables: village (Bororó or Jaguapirú), and ethnicities (Guarani-Kaiowa, Guarani Nhandeva, Terena, and others not predominant in the region); socioeconomic data (age, employment status, income, government benefits, and years of schooling); clinical data: history of cancer, symptoms, and other STIs diagnoses; and behavioral factors: marital status, number of partners in the last year, alcohol use, tobacco use, illicit drug use, share objects (syringes and personal hygiene supplies), condom use. Categorical variables were represented as “yes” or “no”, and numerical variables were categorized later.
All possible actions were taken to reduce bias during data collection. For easy comparisons and identification of errors and inconsistencies, questionnaires were filled out in Redcap with double data entry. Questionnaires were redone to resolve inconsistencies. Incomplete questionnaires were discarded before laboratory analysis.
The exams results were submitted to the Health Unit, where the necessary treatment measures could be taken for the patients in whom an infection was detected.
Sampling and DNA extraction
Vaginal samples were collected using a VAGISPEC® cervical and vaginal brush and placed in a tube containing 1 mL of extraction buffer (EB; 10 mM Tris-HCl pH 8.5, 1 mM EDTA). A total of 300 μL of samples was added to 500 μL of lysis buffer (15 mM sodium citrate, 450 mM NaCl, 0.2% SDS, and 2 mg/mL lysozyme). Phenol-chloroform was used for DNA extraction, and 95% ethanol and 100 μL of 3 M sodium acetate (pH 5.2) were used for precipitation. The precipitate was oven-dried, eluted in 30 μL of TE buffer (10 mM Tris HCl [pH 7.6], 1 mM EDTA), and then frozen at –80°C. DNA was quantified using the UV-Vis Biodrop μLite Spectrophotometer (Biochrom, USA). DNA integrity was evaluated by agarose gel and by amplification of β-globin gene (268 base pairs) representing the internal control of the reaction.
Molecular diagnosis, and direct microscopy of T. vaginalis
All procedures for polymerase chain reaction (PCR), including primers, were performed according to the one described by Gatti et al. (2017). The primer set TVK3/7 (5’AT TGT CGA ACA TTG GTC TTA CCC TC-3’/5`-TCT GTC CCG TCT TCA AGT ATG C-3`), which amplifies a 260 bp DNA fragment, along with a commercial kit: Master Mix (LUDWIG)® was used. The samples were resolved by 1.5% agarose gel electrophoresis and detected by ethidium bromide staining under ultraviolet light for the confirmation of the results. For all PCR assays, T. vaginalis DNA extracted from the culture of ATCC 30236 strain was used as a positive control. Sterile water was used as a negative control to monitor crossover contaminations. The DNA extracted from a PCR-negative sample was used as a negative control [4]. PCR-positive samples were sequenced to confirm the molecular diagnosis in the CREBIO-Jaboticabal/SP (Centro de Biotecnologia, Jaboticabal, SP, Brazil). These sequences were analyzed using Bio Edit software and aligned on BLAST to obtain sequence homology with T. vaginalis.
The samples were smeared directly on the slide using a cervical and vaginal brush. The slides were heat-fixed, Giemsa stained, and then examined under 10x and 40x magnification in a microscope. Trained and experienced personnel processed the readings of the slides. The microscopy also evaluated, besides TV infection, cellular changes, that may indicate HPV infection, as well as the presence of other microorganisms such as C. albicans and G. vaginalis.
Statistical analysis
All the data were analyzed using Statistical Package for the Social Sciences (SPSS) version 22.0 (IBM, Armonk, USA). Descriptive statistics were performed to examine the categorical variables and the results presented in proportions (%). A chi-squared test was used to compare categorical variables. The p < 0.05 was considered statistically significant. A one-tailed Z test was done to test the differences in proportions. The Clopper–Pearson exact test was done to calculate the binomial confidence interval. The independent contribution of each variable toward the chance of trichomoniasis being present was determined by multivariate analysis. All variables of the bivariate analysis were tested to construct the model. After controlling for all potential confounders, binary logistic regression was used to evaluate the association between TV infection and sociodemographic factors at p <0.05, and they were presented as odds ratio (ORs) together with confidence intervals (95% CI).
Results
Sample profile and prevalence of TV
Of 283 samples, 42 (23: questionnaire failure; 19: sampling failure) were excluded. Therefore, 241 indigenous women were screened for the study (Fig 1). The baseline characteristics showed that 81 (33.6%) were aged 18 to 29 years, 200 (83%) were less educated (less than eight years in school), 173 (71.78%) belonged to a family with income below USD 189.00 (which corresponds to minimum Brazilian wage), and 167 (69.29%) were dependent on government benefits (Family Grant). One-hundred and sixty-six (68.88%) women were from the Bororó village; of these, 73.86% were from the Guarani-Kaiowá ethnic group.
An overall prevalence of TV infection using the primer set TVK3/7 was 27.8% (67/241) [95% CI: 22.2–33.9], whereas this rate dropped to 7.41% (17/241) [95% CI: 4.1–11.0] on direct microscopy (Table 1).
Direct microscopy findings
Direct microscopic analysis showed the presence of G. vaginalis and C. albicans in 21 (8.71%) [95% CI: 5.5–13.0] and 8 (3.31%) [95% CI: 1.4–6.4] women, respectively. In addition, human papillomavirus (HPV) infected lesions and atypical squamous cells of unknown significance (ASC-US) were observed in 14 (5.81%) [95% CI: 3.21–9.55]) and 10 (4.14%) [95% CI: 2–7.5]) women evaluated. The presence of concomitant infections was observed in 6 of 67 women, 3 (4.47%) with TV and G. vaginalis; 3 (4.47%) with TV and C. albicans, and 5 (7.45%) with TV and lesions suggestive of infection by HPV and ASC-US (Table 1).
Sociodemographic status and behavior characteristics
The highest proportions of TV-positive women belonged to age groups 18 to 29 years 35.08% [95% CI: 26.22–46.67], from Bororo village 33.13% [95% CI: 26.03–40.85], 34.78% [95% CI: 21.35–50.25] were unemployed, and 31.53% [95% CI: 24.76–39.37] depended on government benefits. A high prevalence of TV infection was seen in single women 39.29% [95% CI: 27.58–52.37], 34.21% [95% CI: 21.21–50.11] of them had multiple sex partners; 29.3% [95% CI: 23.31–35.88] did not use condoms, and 60% [95% CI: 14.66–94.73] had previous history of STIs. In addition, the two women who used illegal drugs were TV positive (Table 2).
Factors associated with TV infection
Additional analysis of the possible risk factors for TV infection showed that the indigenous women who live in the Bororó village have almost three times more risk of infection (p = 0.009), the risk is two times among single women (p = 0.043), and sharing objects increases the risk of infection by four times (p = 0.04). No statistically significant association was found with non-use of condoms (p = 0.261) and aged under 30 years (p = 0.1295). However, when combined variables were analyzed, the risk of TV infection increased four times (p = 0.005) in the group of single women aged below 30 years and three times (p = 0.000) in single women who do not use condoms (Table 3).
Discussion
This is the first study that measures the extent of TV infection among women from an indigenous population in Brazil. Very few existing studies do not have enough data to describe the prevalence and associated factors for trichomoniasis and other STIs in this population [15–17]. Here, we observed a prevalence of 27.8% of the TV infection, which was dependent of laboratory diagnostic technique used [7]. Indeed, PCR (27.8%) and direct microscopy (7.41%) diagnosis showed a considerable difference in the prevalence of TV and might be due to factors, such as bacterial load and test sensitivity [18].
Direct microscopy is frequently used in clinical because it is inexpensive, fast, and non-labor-intensive compared with alternatives such as wet mount preparation, culture, and PCR [19]. In addition, direct microscopy is commonly used in basic health units in Brazil, for the diagnosis of cellular changes, and of pathogenic microorganisms, although with low sensitivity [20], especially in women who do not have symptoms [21]. However, a disadvantage of this convenience is the lower detection rate of direct microscopy relative to PCR as observed in our study (3.75 lower). Taking into account that most cases of TV are asymptomatic or have common symptoms among uninfected patients [19, 22], increasing even more the number of underdiagnosis cases of the disease [10], it is imperative to carry out population screening and to implement information measures on the disease as well as more specific and precise diagnostic methods [19, 22].
The results of this study are similar to the already published ones where the higher prevalence of TV is found in a highly vulnerable population: people deprived of their liberty, sex workers, and populations with low socioeconomic indexes [2, 4, 8, 9]. In this study, 71% of the women were observed to have a family income of less than 189.00 USD, which represents less than 20% of the average family income from the rest of Brazil [19, 22]. The high rates of unemployed women (80.91%), women dependent on government benefits (79.9%), or with low education (less than eight years) (83%), corroborate with other data that indicate the low socioeconomic level of this population [20, 23].
Several demographic and behavioral factors have been associated with TV infection. Our study did not show any association between level of education and family income, but an association was observed in women who depended on government benefits. Also, an association between living in the Bororó village (33.13%) and TV infection was observed, against 16% in the Jaguapiru village, showed that the risk of TV infection increased by 2.5 times in women living in the Bororó village. Data already described in the literature show that the Bororó has a lower socioeconomic index than Jaguapiru village [23], and our study found that only 13% of the women living in the Bororó village had economic activity, while this percentage rises to 32% for women living in the Jaguapiru village. Those findings might be related with the low socioeconomic index, but more studies are necessary to determine if any other factors can be involved.
We also observed that the use of condoms has a low association with TV infection in this population but is important to report that among women said they did not use condoms, 78% were married women. Considering the prevalence among the group of the married women who do not use condoms, the prevalence of TV was 26.03% and among married women who use condoms the prevalence was 6.25%. Besides that, for single women, the risk of TV infection increases by two times and a strong relationship between TV infection and single women who do not use condoms is observed. A prevalence rate of 35.80% was found in women aged below 30 years and TV infection; this number becomes higher (57.89%) when stratified women aged below 30 years and single.
Concomitant infection between TV and G. vaginalis and TV and C. albicans were found in 3 women, respectively. The concomitant infection is commonly found in cases where TV makes the vaginal environment susceptible to infection by C. albicans, and other microorganisms, such as G. vaginalis joins leading to the development of bacterial vaginosis (BV) [24–30]. The presence of atypical squamous cells of unknown significance was observed in 10 of the sample population, and HPV characteristic lesions were observed in 14 women, and among them, 5/24 of women who show lesion on the pap smear, were infected concomitantly with TV. Although HPV has not been diagnosed, the injuries indicates the presence of this viral infection [28, 31]. Some studies have investigated the relationship between BV and STIs, as well as ASC-US and other changes found in the pap smear [28, 32]. These data suggest that the overall prevalence of TV in the indigenous women evaluated may be much higher than the 27.8% found in this study.
There are a few limitations in our study. The participants were enrolled from Basic Health Units of the two indigenous reserves, which affects the generalizability of the results, because sampling is convenient, and thus possible biases may occur, for example, women who had a better chance of accessing the basic health unit, women who are more likely to seek a health service or also women who had some symptom. Sample distribution was unequal between the two reserves, and we must be careful about establishing comparisons. Another limitation is related to variables obtained through the questionnaire, once participants were reluctant to answer some questions, mainly those related to sexual behavior and the use of alcohol and illegal drugs, and thus introducing reporting biases.
In conclusion, a high prevalence of TV infection in indigenous women from two indigenous reserves in the Midwest region of Brazil was observed in this study. Certain groups such as (i) women dependent on government benefits, (ii) single women aged below 30 years who do not use condoms were most likely to have TV infection. In addition, TV infection is underdiagnosis in this population, therefore, improved STI surveillance, with the use of more accurate diagnostic methods, as well as proper management of the risk factors in different indigenous population groups, is vital for health promotion and prevention efforts.
Supporting information
S1 Checklist. STROBE statement—checklist of items that should be included in reports of cross-sectional studies.
https://doi.org/10.1371/journal.pone.0240323.s001
(PDF)
Acknowledgments
We thank the team of nurses from the basic health units of the Dourados/MS indigenous reserve for their support during the sample collection. We also appreciate the support of the Government of the State of Mato Grosso do Sul and, Health Department of the state of Mato Grosso do Sul.
References
- 1. Rowley J, Vander Hoorn S, Korenromp E, Low N, Unemo M, Abu-Raddad LJ, et al. Chlamydia, gonorrhoea, trichomoniasis and syphilis: global prevalence and incidence estimates, 2016. Bull World Health Organ [Internet]. 2019 Aug 1 [cited 2020 Jan 24];97(8):548–562P. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6653813/
- 2.
WHO. Global health sector strategy on sexually transmitted infections 2016–2021. Towards ending STIs. Report. Geneva: 2016 June. Report No. WHO/RHR/16.09; 2016.
- 3. Mao M, Liu HL. Genetic diversity of Trichomonas vaginalis clinical isolates from Henan province in central China. Pathog Glob Health [Internet]. 2015 Jul;109(5):242–6. Available from: https://www.ncbi.nlm.nih.gov/pubmed/26103990 pmid:26103990
- 4. de Waaij DJ, Dubbink JH, Ouburg S, Peters RPH, Morré SA. Prevalence of Trichomonas vaginalis infection and protozoan load in South African women: a cross-sectional study. BMJ Open [Internet]. 2017 Oct 8 [cited 2019 Mar 4];7(10). Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5640031/
- 5. Karaman U, Karadağ N, Atambay M, Arserim Kaya NB, Daldal NU. A comparison of cytological and parasitological methods in the diagnosis of Trichomonas vaginalis. Acta Parasitol Turc 32: 309312
- 6. Donders GGG, Depuydt CE, Bogers J-P, Vereecken AJ. Association of Trichomonas vaginalis and Cytological Abnormalities of the Cervix in Low Risk Women. PLoS One [Internet]. 2013 Dec 30 [cited 2020 Aug 14];8(12). Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3875579/ pmid:24386492
- 7. Fichorova RN, Morrison CS, Chen P-L, Yamamoto HS, Govender Y, Junaid D, et al. Aberrant cervical innate immunity predicts onset of dysbiosis and sexually transmitted infections in women of reproductive age. PLOS ONE [Internet]. 2020 Jan 8 [cited 2020 Jan 16];15(1):e0224359. Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0224359 pmid:31914129
- 8. Masha SC, Owuor C, Ngoi JM, Cools P, Sanders EJ, Vaneechoutte M, et al. Comparative analysis of the vaginal microbiome of pregnant women with either Trichomonas vaginalis or Chlamydia trachomatis. PLOS ONE [Internet]. 2019 Dec 12 [cited 2020 Jan 13];14(12):e0225545. Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0225545 pmid:31830061
- 9. Hobbs MM, Seña AC. Modern diagnosis of Trichomonas vaginalis infection. Sex Transm Infect [Internet]. 2013 Sep;89(6):434–8. Available from: https://www.ncbi.nlm.nih.gov/pubmed/23633669 pmid:23633669
- 10. Gatti FA dos A, Ceolan E, Greco FSR, Santos PC, Klafke GB, de Oliveira GR, et al. The prevalence of trichomoniasis and associated factors among women treated at a university hospital in southern Brazil. PLoS One [Internet]. 2017 Mar 27 [cited 2019 Nov 28];12(3). Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5367685/
- 11. Logie CH, Lys CL, Fujioka J, MacNeill N, Mackay K, Iii ASY. Sexual practices and condom use among a sample of Northern and Indigenous adolescents in Northern Canada: cross-sectional survey results. BMJ Sex Reprod Health [Internet]. 2018 Dec 27 [cited 2019 Mar 4];bmjsrh-2018–200174. Available from: https://srh.bmj.com/content/early/2018/12/27/bmjsrh-2018-200174
- 12. Mabaso N, Naicker C, Nyirenda M, Abbai N. Prevalence and risk factors for Trichomonas vaginalis infection in pregnant women in South Africa. International journal of STD & AIDS. 2020;0956462420907758.
- 13.
SIASI/SESAI. Ministério da Saúde. Secretaria Especial de Saúde Indígena. Sistema de Informação da Atenção à Saúde Indígena. Quantitativo populacional dos indígenas cadastrados no SIASI em 2013 por diversos parâmetros de territorialidade indígena ou nacional. 2014.
- 14. Carvalho N. DST em Populações Indígenas no Brasil–Análise Crítica e Revisão da Literatura. Jornal Brasileiro Brasileiro de Doenças Sexualmente Transmissíveis [Internet]. 2011 [cited 2019 Dec 2];23(3):142–5. Available from: http://www.dst.uff.br/revista23-3-2011/7.%20DST%20em%20Populacoes%20Indigenas%20no%20Brasil.pdf
- 15. Taborda WC, Ferreira SC, Rodrigues D, Stávale JN, Baruzzi RG. Rastreamento do câncer de colo uterino em índias do Parque Indígena do Xingu, Brasil central. Rev Panam Salud Publica [Internet]. 2000 Feb [cited 2020 Feb 11];7:92–6. Available from: https://www.scielosp.org/article/rpsp/2000.v7n2/92-96/pt/ pmid:10748659
- 16. Pereira ER, Oliveira LS de S, Ito LC, Silva LM da, Schmitz M de JM, Pagliaro H. Saúde sexual, reprodutiva e aspectos socioculturais de mulheres indígenas. Rev Bras Promoc Saúde [Internet]. 2014 Dec 30 [cited 2020 Feb 11];27(4):445–54. Available from: https://periodicos.unifor.br/RBPS/article/view/2829
- 17. Norberg AN, de Siqueira APM, Sanches FG, Torres AC, Norberg PRBM, de Carvalho MM, et al. TRICHOMONAS VAGINALIS como possível risco de facilitação na transmissão do vírus da imunosufeciência humana em mulheres indígenas da etnia TERENA. CIÊNCIA & TECNOLOGIA. 2010;80.
- 18. Aslan DL, Gulbahce HE, Stelow EB, Setty S, Brown CA, McGlennen RC, et al. The diagnosis of Trichomonas vaginalis in liquid-based Pap tests: Correlation with PCR. Diagnostic Cytopathology [Internet]. 2005 [cited 2020 Feb 26];32(6):341–4. Available from: https://onlinelibrary.wiley.com/doi/abs/10.1002/dc.20256 pmid:15880709
- 19. Wiringa AE, Ness RB, Darville T, Beigi RH, Haggerty CL. Trichomonas vaginalis, endometritis and sequelae among women with clinically suspected pelvic inflammatory disease. Sex Transm Infect. 2020 Sep;96(6):436–8. pmid:31719170
- 20. de Oliveira ACA, Domingues MF, Neufeld PM, Fleury M, Nogueira Neto JF. Comparison between Conventional Cytology and Liquid-Based Cytology in the Tertiary Brazilian Navy Hospital in Rio de Janeiro. Acta Cytol. 2020 Jun 9;1–8.
- 21. Fonseca THS, Oliveira FMS, Alacoque M, Rocha MI, Leite HV, Santos JFG, et al. Immunocytochemistry Improving the Diagnosis of Trichomonas vaginalis Infections. Biomed Res Int. 2017;2017:5642535. pmid:28424786
- 22. Rogers SM, Turner CF, Hobbs M, Miller WC, Tan S, Roman AM, et al. Epidemiology of Undiagnosed Trichomoniasis in a Probability Sample of Urban Young Adults. PLoS One [Internet]. 2014 Mar 13 [cited 2020 Aug 14];9(3). Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3953116/
- 23. Jorge CA de S. Insegurança alimentar entre famílias indígenas de Dourados, Mato Grosso do Sul, Brasil. 2015;
- 24. Lichtenstein B, Desmond RA, Schwebke JR. Partnership concurrency status and condom use among women diagnosed with Trichomonas vaginalis. Womens Health Issues. 2008 Oct;18(5):369–74. pmid:18657997
- 25. López-Monteon A, Gómez-Figueroa FS, Ramos-Poceros G, Guzmán-Gómez D, Ramos-Ligonio A. Codetection of Trichomonas vaginalis and Candida albicans by PCR in Urine Samples in a Low-Risk Population Attended in a Clinic First Level in Central Veracruz, Mexico. Biomed Res Int [Internet]. 2013 [cited 2020 Feb 24];2013. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3773406/
- 26. Nsagha DS, Zofou D, Assob JCN, Njunda AL, Nchang CD, MvoNgum N, et al. The epidemiology of Trichomonas vaginalis, Gardnerella vaginalis and Candida albicans co-infections in women attending the Yaounde University teaching hospital. Am J Epidemiol Infect Dis. 2015;3(2):28–31.
- 27. Oliveira AB, França CA da S, Santos TB dos, Garcia MAF, Tsutsumi MY, Brito Júnior LC de. Prevalência de gardnerella e mobiluncus em exames de colpocitologia em Tome-Açu, Pará: Prevalence of gardnerella and mobiluncus in vaginal cytology examinations in Tome-Açu—Pará. Revista Paraense de Medicina [Internet]. 2007 Dec [cited 2020 Feb 27];21(4):47–51. Available from: http://scielo.iec.gov.br/scielo.php?script=sci_abstract&pid=S0101-59072007000400008&lng=pt&nrm=iso&tlng=pt
- 28. Onderdonk AB, Delaney ML, Fichorova RN. The Human Microbiome during Bacterial Vaginosis. Clin Microbiol Rev [Internet]. 2016 Apr [cited 2020 Feb 27];29(2):223–38. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4786887/ pmid:26864580
- 29. Baruah FK, Sharma A, Das C, Hazarika NK, Hussain JH. Role of Gardnerella vaginalis as an etiological agent of bacterial vaginosis. Iran J Microbiol [Internet]. 2014 Dec [cited 2020 Feb 27];6(6):409–14. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4411427/ pmid:25926959
- 30. Kamga YM, Ngunde JP, Akoachere J-FKT. Prevalence of bacterial vaginosis and associated risk factors in pregnant women receiving antenatal care at the Kumba Health District (KHD), Cameroon. BMC Pregnancy Childbirth [Internet]. 2019 May 10 [cited 2020 Feb 27];19. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6511194/
- 31. Katki HA, Schiffman M, Castle PE, Fetterman B, Poitras NE, Lorey T, et al. Five-year risk of CIN3+ and cervical cancer for women with HPV testing of ASC-US Pap results. J Low Genit Tract Dis [Internet]. 2013 Apr [cited 2020 Mar 10];17(5 0 1):S36–42. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3616508/
- 32. Vieira-Baptista P, Lima-Silva J, Pinto C, Saldanha C, Beires J, Martinez-de-Oliveira J, et al. Bacterial vaginosis, aerobic vaginitis, vaginal inflammation and major Pap smear abnormalities. Eur J Clin Microbiol Infect Dis [Internet]. 2016 Apr 1 [cited 2020 Feb 28];35(4):657–64. Available from: https://doi.org/10.1007/s10096-016-2584-1 pmid:26810061