Displaying 1-10 letters out of 182 published
In support of a structured approach to service design and evaluation in chlamydia screening
We read with interest the recent article by Chandrasekaran et al, which analysed national surveillance data on chlamydia testing and diagnoses among young adults in England in 2012. The paper raises a number of important points of relevance for the National Chlamydia Screening Programme in England.
Firstly, the authors' findings further support the known association between deprivation and chlamydia infection[2;3]. Although Chandrasekaran et al present an ecological study, this relationship has also been demonstrated in individual level analyses and emphasises the importance of chlamydia screening delivery in socioeconomically deprived areas. For local authorities thinking about the implications of these findings for their own populations, it is also worth noting that within a single local authority area, levels of deprivation will vary. Therefore decisions about focussing of resources need to be considered at several levels.
The observation that areas with a lower proportion of tests carried out in GUM clinics were less likely to achieve a detection rate of 2,300/100,000 population is also an important one. Chlamydia infections are not restricted to young adults with higher risk sexual behaviours, such as multiple sexual partners, nor to those who attend GUM clinics[2;3]. Testing in non-GUM clinic settings such as sexual and reproductive health services, primary care and via the internet is therefore an essential component of comprehensive chlamydia control.
Along with differences in infection risk in different populations, the other driver of variation in detection rates is testing coverage, as the authors themselves point out. Although the relationship between coverage and detection rates was not explored explicitly in this paper, we note that coverage was higher in more deprived local authorities. In national surveillance data from 2015, local authorities with higher coverage tended to have higher detection rates. This suggests that in 2012, chlamydia screening activity was, to some extent, already focussed in areas at greatest need. However, more could be done to increase detection rates as we know that infections go undiagnosed3, with the consequent potential impact on reproductive health. The old adage of 'seek and ye shall find' holds true to a large extent with chlamydia testing among young adults; the decision for local authorities is how best to use the available resources to maximise the benefit of every test.
To that end, we also welcome the authors' recommendation that local authorities be encouraged to use their data to inform service planning and evaluation. As the authors conclude, this understanding of the data should not be limited to a narrow focus on the detection rate indicator alone. Diagnosis is only one step of the process by which chlamydia screening can identify and treat infections. Understanding of the population(s) at risk, rates of testing, diagnosis, treatment, partner notification and re- testing are all needed to ensure a quality service. In recognition of this, the NCSP is already working with local authorities and service providers to use both nationally- and locally-collated data relating to the whole of the chlamydia care pathway to inform service improvement activity. We believe this structured approach to service design and evaluation will ensure that commissioners are best able to allocate limited resources to achieve the maximum benefit for the population.
 Chandrasekaran L, Davies B, Eaton JW, Ward H. Chlamydia diagnosis rate in England in 2012: an ecological study of local authorities. Sex Transm Infect 2016.
 Sonnenberg P, Clifton S, Beddows S, Field N, Soldan K, Tanton C et al. Prevalence, risk factors, and uptake of interventions for sexually transmitted infections in Britain: findings from the National Surveys of Sexual Attitudes and Lifestyles (Natsal). Lancet 2013; 382(9907):1795- 1806.
 Woodhall SC, Soldan K, Sonnenberg P, Mercer CH, Clifton S, Saunders P et al. Is chlamydia screening reaching young adults at risk of infection? Findings from the third National Survey of Sexual attitudes and Lifestyles (Natsal-3). Sexually Tranmitted Infections 2016; 92(3):218-227.
 Public Health England. Sexually transmitted infections and chlamydia screening in England, 2015. Health Protection Report 2016; 10(22).
 Price MJ, Ades AE, Soldan K, Welton NJ, Macleod J, Simms I et al. The natural history of Chlamydia trachomatis infection in women: a multi parameter evidence synthesis. Health Technology Assessment 2016; 20(22).
 Public Health England. NCSP: Care pathway. 2016. Available at: https://www.gov.uk/government/publications/ncsp-chlamydia-care-pathway Accessed 2 Sep 2016
Conflict of Interest:
All authors are employed by Public Health England and contribute to the implementation, monitoring and/or evaluation of the National Chlamydia Screening Programme in England.
Re: Retesting Chlamydia trachomatis in a GUM clinic in London, UK
Thank you very much for carefully reading our article and for your positive feedback. We have read your E-letter with great interest. We are pleased that our publication contributed to adjustment of your policy concerning retesting. Implementing a text message reminder and lengthening the follow up period to 3 months is likely to elevate the return rate and positivity rate. According to our research, you may even consider lengthening the follow up period to 6 months to yield even more chlamydia reinfections.
In your letter you show that you already achieve a relatively high return rate of 26.8% without sending a text message reminder. Also, in research from Burton et al, 2014, the return rate was high with 35% without sending a text message reminder. These are much higher return rates than in our control group (9.2%). In your E-letter (Ahmed et al. STI, 2016), you question whether patients in the Netherlands are advised to do a repeat test. We do have an informal guideline concerning this advice, though it is not certain that every clinic in our study group gave this advice. Therefore we cannot state that this retest-advice is consistently given, and that could have (in part) caused our relatively low return-rates in the control group. Also, you state in the E-letter that sexual health appointments in your service are available by booking in advance or on the day. It is unclear to me whether this means that an appointment for retest is already made after initial consultation or that patients who want to do a retest can come at any day. In our study, booking in advance was not done. In our STI clinics, the usual waiting time for non-emergency sexual health consultations is 2-3 weeks. This could be an additional factor in the difference between our return rate and the return rate of the UK research described.
In the Netherlands, the sexual health clinics are exploring and implementing cost-effective strategies to lower the threshold for (re- )testing on STI. As an example of how to make retesting more (cost-) effective, we like to refer to a Dutch article by Gotz, et al , where the retest participation was higher in the patient-group that received a testkit at their home address (46%, 50/109), compared to the group asked to visit the STI clinic for retesting without an appointment (23%, 25/107). Home-based testkits can be a good method to increase the re- attendance rate. Though some STI-clinics in the Netherlands implement this strategy for low-risk patients, it hasn't yet been implemented for the purpose of a retest. This might, however, be an interesting cost-effective way to identify chlamydia reinfections.
 G?tz HM, Wolfers MEG, Luijendijk A, van den Broek IVG. Retesting for genital Chlamydia trachomatis among visitors of a sexually transmitted infections clinic: randomized intervention trial of home- versus clinic- based recall. BMC Infectious Diseases 2013, 13:239
Conflict of Interest:
Source data used is not appropriate for this comparison
I am flabbergasted that this public health article exists at all. Where is the peer review. The problem lies in the appropriateness of source data which was used. In an email exchange I confirmed that I understood that the authors did indeed divide interviewed sex workers into two groups, one that experienced violence in the single preceding week and a second group that did not. They then compared health data for differences between the two groups. The source data came from the 2007 Survey of Sexual and Reproductive Health of Sex Workers in Thailand. This was a huge project with many volunteers to conduct 120 question interviews. The result is 815 in depth personal interviews. The abstract of this study I am criticizing says that 14.6% of these 815 experienced violence on the job in only one week before their interview. This is a huge red flag for anyone knowledgable regarding this issue. There are other studies including my own that might agree that violence reported is in the low to mid teens but that is true when asking about violence over one year, but not one week. My own micro-research survey of 100 sex workers in the Nana Plaza area of Bangkok reported 13% violence over a year. But when the response of "a raised voice or argument" (no physical contact) was discarded, the level of physical violence in one year dropped to less than 2% out of 98 good surveys.
This tells me it is time to ask how the 2007 study in Thailand defined violence. I have a copy. Of 120 questions, only one can claim to speak to levels of violence. Question Q804 says: In the last seven days, have any of the following happened to you at work? There are six possible choices. Only two choices involve physical contact between the sex worker and her customer. Here are the choices: Yelled at / Hit / Forced to perform sex acts you did not want to perform / Not paid / Paid less than agreed / Made to do other things you didn't want to do. Two of the six choices are about payment. Yet a YES answer to any of these six choices will put this interviewee in the "violence" group. So, you be the judge. Is this a proper way to create two discrete groups appropriate for comparison? When four of the six choices used to define violence do not necessarily involve any physical contact, at least none that is different then the other group experienced, there are no grounds to assume anything about health differences between these fatuously assembled groups based on violence.
Just my opinion. Respond to tell me what you think.
Conflict of Interest:
My only competing interest is that I oppose the hyperbole and exaggeration surrounding the issues of sex trafficking and sex work. This is a minor offense but claiming 14.6% violence in one week based on only poorly designed question is inflammatory.
Retesting Chlamydia trachomatis in a GUM clinic in London, UK
We read with interest the recent report by Kampman et al, 2016  on the effect of text reminders on patients attending for repeat chlamydia tests and chlamydia diagnosis.
In our service, the St. Ann's Sexual Health Centre, a GUM clinic in London, UK, our routine practice was to verbally advise patients treated for chlamydia to re-attend 6-8 weeks after treatment for re-testing. Sexual health appointments are available either by booking in advance or on the day depending on timing and capacity. We reviewed our overall practice in managing chlamydia infections against the British Association for Sexual Health and HIV (BASHH) national guidelines, but with a particular focus on repeat testing. BASHH recommend a test of cure (testing at 3-5 weeks) in certain groups (e.g. pregnant women) and repeat testing 3 months after treatment in under 25 year olds, and considered, in high risk groups. All patients with a positive chlamydia NAAT result over a two month period in 2014 were identified and their clinical care evaluated.
108 patients were identified compared to 838 analysed by Kampman et al spanning over a year as well as from ten STI clinics. Our cohort represented our local demographics; 54% female, 72.6% under the age of 25 years old, 41.6% of Black Afro-Caribbean or Black British ethnicity and 96.6% heterosexual. 39% were symptomatic compared to 32% in the Netherlands cohort.
36% (65/180) attended for a repeat test in our cohort compared to the Netherlands group where 9.2% (140/1530) returned without reminder and 30.6% (253/838) in the study group who received a text message after 6 months. The median time to attendance for a repeat test after treatment was 6 weeks (IQR (6-8) in our cohort, compared to re-testing being concentrated within 5-8 months in the study group of Kampman et al. At our centre only one patient tested positive for CT which was due to re- infection, whereas 20.4% (56/275) of the Netherlands study group had a repeat infection.
Our data reflects that of the other UK data highlighted, from Burton et al, 2014, with a re-test rate in their control group who did not receive a text message, of 35% (92/226). Although the authors state a comparison cannot be made given the higher re-test rate of the UK group compared to their control group, some inferences can be made. It is interesting that there is an increase of 26.8% in those attending for a repeat test without a text reminder in our group. Although the total number included in the Netherlands group is larger compared to ours, the former was data collated over a year at ten sites, compared to over two months at our site alone. Kampman et al do not mention whether patients were advised to have a repeat test, unlike our patients who are all informed about repeat testing after 6-8 weeks at the time of treatment. This is a simple intervention which could enhance their rate of re- attendance. Furthermore, the number of re-infections was significantly greater than our rate. This may reflect the varying denominators and/or the greater length of time before re-testing (6 months compared to 6-8 weeks after treatment), as this potentially allows for a greater time period to acquire re-infection. The higher numbers re-testing in our group may also be due to the shorter interval between treatment and re-testing.
Overall our centre met the BASHH 2015 standards in the management of chlamydia. However, we felt that a move from re-testing at 6 weeks to re- testing at 3 months in high risk groups (patients aged < 25 years and MSM) would be more cost effective as it will identify any treatment failures and potentially more re-infections.
We continue to inform patients about re-testing when they are being treated and have also introduced text reminders at 3 months. Text reminders are an acceptable, easy and cost-effective strategy to increase efficiency especially given NHS targets and cuts to public health funding.
References 1)Kampman CJG, Koedijk FDH, Driessen-Hulshof HCM, et al. Retesting young STI clinic visitors with urogenital Chlamydia trachomatis infection in the Netherlands; response to a text message reminder and reinfection rates: a prospective study with historical controls.Sex Transm Infect 2016;92:124- 9. 2) Burton J, Brook G, McSorley J, et al. The utility of short message service (SMS) texts to remind patients at higher risk of STIs and HIV to reattend for testing: a controlled before and after study. Sex Transm Infect 2014;90:11-13.?
Conflict of Interest:
Awareness program Vs HPV Vaccination to prevent Cervical cancer
I would like to welcome authors interest in analysing the data regarding knowledge of HPV among the male and females. HPV is commonly implicated virus in causing cervical cancer.Cervical cancer acompass top leading cause of cancer deaths in Nepal and other developing countries.Early age vaccination has shown positive results in preventing HPV trasmission.However in country like Nepal where there is no provison of HPV vaccination,awareness programs regarding the HPV transmission and its role in causing cervical cancer can prevent it in upcoming days. since cervical cancer incidence is in middle aged womed,awareness program regarding the neccessity of pap smear test can help in early diagnosis and timely intervention. since multiple sex partner is likely cause for HPV transmisson ,male should be equally aware of it. Future research should compare the effectiveness of HPV vaccine vs single sex partner in prevention of cervical cancer. Awareness in youngsters regarding HPV and its role in cervical cancer can be efffective means to control HPV transmission in resource poor developing countries.Also womens need to be encouraged to do pap smear test after 35 years in yearly basis.
Conflict of Interest:
Utility of Chlamydia trachomatis genotyping in assessment of child sexual abuse
The editorial by Giffard et al. rightly addresses the issue of the potential clinical and social response to the detection of C.trachomatis in urogenital (UGT) specimens from young children.  Clinical guidelines frequently state that detection of a sexually transmissible agent in a UGT specimen of a child is strongly indicative of sexual abuse (SA), and even in the absence of disclosure of SA, initiates an investigation by child protection services.  However this may not hold true always, as detection of sexually transmitted infection (STI) in UGT samples from young children is not always a consequence of conventional sexual contact. Potential explanations are autoinoculation from an ocular source, perinatal mother to child transmission or contamination of specimens. 
Autoinoculation of C.trachomatis from the ocular infection to the UGT site is a well-established phenomenon and leads to the detection of C.trachomatis in UGT specimens even in the absence of any sexual contact.  This particularly is relevant to a country like India, where trachoma still remains endemic  and is not considered as an STI. As discussed by Giffard et al, the relevance of genotyping in such situation cannot be underscored. We support their suggestion of the inclusion of C.trachomatis genotyping into formal guidelines for examining the source of STIs in young children in areas where trachoma genotypes may continue to circulate. The authors further state that it is also important to know the trachoma and UGT genotypes circulating in the conventional adult sexual networks in the area, so as to establish the possible route of transmission. However no studies are available from India for the frequency of trachoma genotypes in adult and pediatric UGT specimens. This further confounds the issue whether the detection of C.trachomatis in a pediatric UGT is a reliable indicator that SA has occurred.
There are reports of trachoma genotypes in UGT specimens, with genotype B being the most commonly reported. [5,6] If the frequency of trachoma genotypes detected in pediatric UGT specimens is more in comparison to the trachoma genotypes from UGT specimens of adults, then the route of transmission is more in favor of autoinoculation than transmission from adult sexual networks and this is of potential significance in the child protection context. However, a UGT genotype in such case, if detected from the UGT specimens of a child would represent stronger evidence of abuse.
In conclusion, genotyping of C.trachomatis from pediatric UGT specimens and correlating it with the circulating genotypes in the adult sexual networks seems to be a better approach to determine whether the organism has been acquired through sexual contact or not. Continuous surveillance of C.trachomatis genotypes in adults and pediatric specimens can unravel the complex transmission dynamics of this organism.
1. Giffard PM, Singh G, Garland SM. What does Chlamydia trachomatis detection in a urogenital specimen from a young child mean? Sex Transm Infect. 2016 Apr 15. [Epub ahead of print]
2. Workowski KA, Bolan GA. Sexually transmitted diseases treatment guidelines, 2015. MMWR Recomm Rep 2015;64:1-137.
3. Giffard PM, Brenner NC, Tabrizi SN, et al. Chlamydia trachomatis genotypes in a cross-sectional study of urogenital samples from remote Northern and Central Australia. BMJ Open. 2016 Jan 6;6(1):e009624.
4. WHO Status of endemicity for blinding trachoma data by country, 2012. Available from: http://www.who.int/gho/neglected_diseases/trachoma/en/. WHO, 2012
5. Psarrakos P, Papadogeorgakis E, Sachse K, et al. Chlamydia trachomatis ompA genotypes in male patients with urethritis in Greece: conservation of the serovar distribution and evidence for mixed infections with Chlamydophila abortus. Mol Cell Probes 2011;25:168-73.
6. Takahashi S, Yamazaki T, Satoh K, et al. Longitudinal epidemiology of Chlamydia trachomatis serovars in female patients in Japan. Jpn J Infect Dis 2007;60:374-6.
Conflict of Interest:
Re:Alternative forms of penile foreskin cutting and HIV infection in Papua New Guinea
We thank the author for her interest in our paper and are happy that she was able to exactly reproduce our findings.
As explicitly stated - ours was an ecological study, and thus used aggregate data only. Here we comment on the author's additional statistical analysis and interpretations:
First, the author of the reply apparently did not test "individual results" which we assume means the single, different types of foreskin cutting. The statistical analysis stated in this context do not test the "single types of foreskin cuttings" vs no cutting, but rather refer to "circumcision" vs "dorsal/longitudinal cut or no cut at all" and "dorsal/longitudinal cut" vs "circumcision or not cut at all". These tests do not confer any additional information: in contrast, if assume that "any cut" is associated with HIV prevalence (as our results clearly suggest), then it should logically not come as a surprise that "one specific type of cut" vs "another type of cut plus no cut at all' is not significant. This approach is muddling up the baseline of "no cut" with "another type of cut" and thus will water down any association of penile cutting with HIV.
Second, we point out that the regression coefficient per se cannot be used to judge the strength of an association (only its direction / slope of the resulting regression line). It is consequently a misconception when the author of the reply states - based on regression coefficients - that the association between condom use and HIV prevalence is stronger than that between any cuts and HIV. In fact, the reverse can be seen to be true when correct correlation coefficients (or their squares, the coefficients of determination) are used.
Finally, more sophisticated multivariate analyses cannot - and should not - be applied to this type of ecological data to clarify things further. In contrast to making "bold" and "declarative" statements, every effort was made to restrict the interpretation of the results to "association" as opposed to a causal effect. Please see the paragraph where we explicitly highlight caution with respect to the interpretation of results in this study (at the end of the discussion). Our paper also explicitly stated that the study is of "hypothesis generating" character rather than of any "confirmative" nature.
Conflict of Interest:
Examining the authors' selected risk factors and the implications on a particular group of individuals
In the article, the authors' mention this study as being the first to be carried out on young sexually active women in post-secondary schools in the UK. They identified pelvic inflammatory disease (PID) in 1.6% of the individuals recruited for this study which was low because many individuals were lost during follow-up. However, they mentioned in the conclusions that medical reports were obtained from clinics for those lost during follow-up, but made no mention of obtaining individual consents before accessing their medical information from clinics and doctors. I identified two sources of error in this study: First, sample collection in the study was performed by participants and not trained personnel which will definitely lead to differential bias because the clinical samples cannot clearly differentiate cases from non-cases. Secondly, potential confounders were not adjusted which could be a source of bias. A significant issue in this study was the risk factors proposed for contracting sexually transmissible disease, hence PIDs among the participants recruited. Black ethnicity was identified as a risk factor for this study with no explanation as to why they considered only black ethnicity (and not ethnicity in general). No information on the diversity of the population was mentioned which makes their results bias towards a certain group of individuals. The authors failed to explain why ethnicity is placed as a risk factor for contracting PIDs in the first place.
Their conclusions for this study could set a damaging public image for individuals in the specified ethnic group. Questions like, what makes this ethnic group more susceptible to contracting PID's and why poor sexual health is associated to blacks in the UK should be thoroughly explained before conclusions are drawn. To belong to a particular ethnic group would never place you at risk for developing a particular infection except for the case of gene involvement in the disease or particular practices unique to the group which may/or may not predispose you to developing the disease in question. PIDs are complications of sexually transmitted diseases which depend on individuals' choices about their lifestyle and this has nothing to do with your ethnic background, race, sex or religion. More research on cultural aspects and behaviors in such groups need to be carried out in order for such conclusions to be made for any ethnic group studied. Reading this article makes you wonder if the study was focused only on identifying black women with PIDs in schools or whether it focused on identifying the prevalence among a diverse group of young women in the population. It would be best if the authors present data on the diversity of ethnic groups participating in this study and then make relative comparisons between the groups in terms of loss to follow-up and prevalence of PIDs.
While this study contributes greatly in assessing risks for sexually transmissible diseases and complications among young sexually active women, it is bias towards a particular group of individuals -black ethnicity and indirectly places a bad image on this group which could be detrimental to them if this information is exposed to the public.
By Akwo Ngwinui Awahsaa Diploma student Community Health and Humanities Memorial University of Newfoundland Canada
Conflict of Interest:
Response to "Comparison of age-specific patterns of sexual behaviour and anal HPV prevalence in homosexual men with patterns in women"
Dear Editor, with great interest we read the article by Poynten and collaborators (1), who investigated the possible relation between recent sexual behaviour and age-specific prevalence of anal HPV infection in men who have sex with men (MSM) and cervical HPV infection in women. The authors used the sexual behavioural data of previously published surveys conducted on these populations. Their conclusions regarding the association of the age- specific pattern of sexual behaviour with that of anal HPV prevalence among MSM are largely consistent with the results of our recent study. This investigated the association between recent sexual behaviour and anal HPV infection among 408 HIV-uninfected MSM recruited at a sexual-health clinic (2). Our results showed an age-independent trend for the prevalence of any HPV genotype and also for that of high-risk genotypes. Moreover, the stability of the HPV prevalence trend was supported by a non- significant change in the median age of sexual partners across different age groups and by a substantial increase in the median number of recent sexual partners with age. This indicates that, among MSM, older individuals still maintain an active sex life, as rightly underlined by Poynten and collaborators, and that the pattern of mixing-age in sexual partnership, specific for this population, is an important determinant of ongoing exposure to HPV throughout life. Thus, as Poynten and collaborators, we do believe that recent sexual behaviour is the driving reason for the persistently high prevalence of anal HPV infection in MSM. However, in addition to the high number of new partners, their age characteristics are likely to contribute strongly to this phenomenon. We believe that the study by Poynten and collaborators, together with our findings, significantly contribute to shedding more light on the reasons behind the stable prevalence of anal HPV infection among MSM and have significant implications on the vaccination strategies to be adopted for these individuals.
1. Poynten IM, Machalek D, Templeton D, et al. Comparison of age- specific patterns of sexual behavior and anal HPV prevalence in homosexual men with patterns in women. Sex Trans Infect August 25, 2015: doi:10.1136/sextrans-2015-052032.
2. Dona' MG, Latini A, Benevolo M, et al. Anal human papillomavirus infection prevalence in men who have sex with men is age-independent: a role for recent sexual behavior? Future Microbiol 2014;9:837-44
Conflict of Interest:
Alternative forms of penile foreskin cutting and HIV infection in Papua New Guinea
I read with concern the manuscript by MacLaren DJ et al which states: "Alternative forms of penile foreskin cutting may be associated with reduced HIV infection risk in Papua New Guinea." Using data described in the manuscript, I was able to exactly replicate the authors' primary numerical finding. However, results of additional analyses not reported in the manuscript directly conflict with the key message regarding a potential association between alternative forms of penile foreskin cutting and reduced HIV risk.
First, the manuscript does not present individual results according type of penile foreskin cutting. Neither of the individual associations between HIV prevalence and prevalence of circumcision or dorsal longitudinal cut alone reach statistical significance (P=0.1756 and P=0.1327, respectively).
Second, no results are reported for associations between HIV prevalence and other risk factors for HIV acquisition. Yet, prevalence of condom use at last sex is significantly associated with HIV prevalence (P=0.0089) and has a high coefficient of determination (R2=0.9823). Furthermore, the strength of the association appears to be as strong, or stronger, than that found for circumcision/dorsal longitudinal cut. The regression coefficient for condom use at last sex (?=-0.07848) is approximately three -fold stronger than the coefficient for circumcision/dorsal longitudinal cut (?=-0.02322).
The manuscript makes bold statements about alternative forms of penile foreskin cutting and reduced HIV risk. Yet, these claims are not supported by the individual associations with each type of penile of foreskin cutting. Additionally, the claims are predicated in part on an apparent ruling-out of other risk factors for HIV acquisition. Applying the same analytic approach with prevalence of condom use yields a similar, if not stronger, association with HIV prevalence. Taken together, I question the appropriateness of the manuscript's declarative title and the credibility of its key message regarding alternative forms of penile foreskin cutting and reduced HIV risk.
1. MacLaren DJ, McBride WJH, Kelly GC, et al. HIV prevalence is strongly associated with geographical variations in male circumcision and foreskin cutting in Papua New Guinea: an ecological study. Sexually Transmitted Infections. Published Online First: 30 June 2015 doi: 10.1136/sextrans-2014-051970.
Conflict of Interest: