Male circumcision and sexually transmitted infections in Botswana

This study set out to investigate the influence of male circumcision and other factors on sexually transmitted infections in Botswana. A syndromic approach, which diagnoses a sexually transmitted infection based on the presence of urethral discharge or genital ulcers rather than on laboratory tests, was used. The data were from the 2001 Botswana AIDS Impact Survey where a nationally representative, randomly selected sample of men and women aged 10-64 years were interviewed in both urban and rural areas. The sample selected for this study consisted of 216,480 men aged 15-64 years who had ever had sexual intercourse. The logistic regression technique was executed to examine the association between male circumcision and self-reported urethral discharge or genital ulcers, while controlling for all other independent variables in the analysis. The main finding of this study was that among men who are circumcised, the odds for self-reported urethral discharge or genital ulcers are significantly lower than for those men who are not circumcised in both urban and rural Botswana. The analysis also showed that the odds in favour of self-reported urethral discharge or genital ulcers, for men who drink alcohol, are twice as large as those for men who do not drink alcohol, controlling for all other independent variables in the analysis. Religion and ethnicity also came through as factors exerting a protective influence against self-reported symptoms of sexually transmitted infections. The conclusion is that while male circumcision appears to be significantly associated with the risk for self-reported urethral discharge or genital ulcers, it is man's behaviour, irrespective of ethnicity or religious dictates, that continues to play a vital role in protection against self-reported symptoms of sexually transmitted infections in Botswana.     

Sexual networks: implications for the transmission of sexually transmitted infections

The structures of sexual networks are essential for understanding the dynamics of sexually transmitted infections. Standard epidemiological models largely disregard the complex patterns of intimate contacts. Social network analysis offers important insight into how to conceptualize and model social interaction and has the potential to greatly enhance the understanding of disease epidemics.     

The diaphragm and lubricant gel for prevention of cervical sexually transmitted infections: results of a randomized controlled trial

Background

We evaluated the effectiveness of the Ortho All-Flex Diaphragm, lubricant gel (Replens®) and condoms compared to condoms alone on the incidence of chlamydial and gonococcal infections in an open-label randomized controlled trial among women at risk of HIV/STI infections.

Methods

We randomized 5045 sexually-active women at three sites in Southern Africa. Participants who tested positive for curable STIs were treated prior to enrollment as per local guidelines. Women were followed quarterly and tested for Chlamydia trachomatis (CT) or Neisseria gonorrhoeae (GC) infection by nucleic-acid amplification testing (Roche Amplicor®) using first-catch urine specimens. STIs detected at follow-up visits were treated. We compared the incidence of first infection after randomization between study arms in both intent-to-treat (ITT) and per-protocol populations.

Findings

Baseline demographic, behavioral and clinical characteristics were balanced across study arms. Nearly 80% of participants were under 35 years of age. Median follow-up time was 21 months and the retention rate was over 93%. There were 471 first chlamydia infections, 247 in the intervention arm and 224 in the control arm with an overall incidence of 6.2/100 woman-years (wy) (relative hazard (RH) 1.11, 95% Confidence Interval (CI): 0.93–1.33; p = 0.25) and 192 first gonococcal infections, 95 in the intervention arm and 97 in the control arm with an overall incidence of 2.4/100wy (RH 0.98, 95%CI: 0.74–1.30; p = 0.90). Per protocol results indicated that when diaphragm adherence was defined as “always use” since the last visit, there was a significant reduction in the incidence of GC infection among women randomized to the intervention arm (RH 0.61, 95%CI: 0.41–0.91, P = 0.02).

Interpretation

There was no difference by study arm in the rate of acquisition of CT or GC. However, our per-protocol results suggest that consistent use of the diaphragm may reduce acquisition of GC.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00121459","term_id":"NCT00121459"}}NCT00121459 [{"type":"clinical-trial","attrs":{"text":"NCT00121459","term_id":"NCT00121459"}}NCT00121459]     

Sex-specific immunization for sexually transmitted infections such as human papillomavirus: insights from mathematical models

Background

Sex-specific differences regarding the transmissibility and the course of infection are the rule rather than the exception in the epidemiology of sexually transmitted infections (STIs). Human papillomavirus (HPV) provides an example: disease outcomes differ between men and women, as does the potential for transmission to the opposite sex. HPV vaccination of preadolescent girls was recently introduced in many countries, and inclusion of boys in the vaccination programs is being discussed. Here, we address the question of whether vaccinating females only, males only, or both sexes is the most effective strategy to reduce the population prevalence of an STI like HPV.

Methods and Findings

We use a range of two-sex transmission models with varying detail to identify general criteria for allocating a prophylactic vaccine between both sexes. The most effective reduction in the population prevalence of infection is always achieved by single-sex vaccination; vaccinating the sex with the highest prevaccine prevalence is the preferred strategy in most circumstances. Exceptions arise only when the higher prevaccine prevalence is due to a substantially lower rate of natural immunity, or when natural immunity is lifelong, and a prolonged duration of infectiousness coincides with increased transmissibility. Predictions from simple models were confirmed in simulations based on an elaborate HPV transmission model. Our analysis suggests that relatively inefficient genital transmission from males to females might render male vaccination more effective in reducing overall infection levels. However, most existing HPV vaccination programs have achieved sufficient coverage to continue with female-only vaccination.

Conclusions

Increasing vaccine uptake among preadolescent girls is more effective in reducing HPV infection than including boys in existing vaccination programs. As a rule, directing prophylactic immunization at the sex with the highest prevaccine prevalence results in the largest reduction of the population prevalence. Please see later in the article for the Editors'' Summary     

Epidemiology of sexually transmitted Chlamydia trachomatis infections in male patients

868 male urethritis patients were studied for the presence of chlamydiae in the 1981-1986 period. 36% of NGU, 31.3% of gonococcal urethritis and 58.8% of PGU urethritis patients presented C. trachomatis infections as detected by cell culture inoculation. Chlamydial infection was recorded more often in the 21-30 years age group (30.8%), in unmarried patients (70.6%), as well as in people with low educational degree (46.6% of cases), 42.3% of the C. trachomatis cases were already confronted with one or more urethritis episodes. 24.7% of patients have been subjected to a previous antichlamydial treatment.     

A stochastic model for the spread of a sexually transmitted disease which results in a scale-free network

A stochastic model for the spread of a sexually transmitted disease (STD) is presented. To reflect varying degrees of promiscuity among individuals it is assumed that the infectivity of any infected individual is proportional to the number of previous contacts the individual has had with other infected individuals. In both the simple single-sex model and in the more complex two-sex model, the tree graphs of the infection exhibit scale-free network behaviour (i.e. power-law behaviour in the upper tail of the degree distribution). The distributions of the size of the infection and of the ring number (distance from the original source of the infection) are determined.     

Sexual partners,sexually transmitted infections,and prostate cancer risk

Background: The etiology of prostate cancer (PCa) is poorly understood. Sexual activity and sexually transmitted infections (STIs) are among factors under scrutiny, with controversial findings to date. Methods: We examined the association between the number and gender of sexual partners, STIs and PCa risk in the context of PROtEuS, a population-based case–control study set amongst the mainly French-speaking population in Montreal, Canada. The study included 1590 histologically-confirmed PCa cases diagnosed in a Montreal French hospital between 2005 and 2009, and 1618 population controls ascertained from the French electoral list, Montreal residents, frequency-matched to cases by age. In-person interviews elicited information on sociodemographic, lifestyle and environmental factors. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) between sexually related factors and PCa risk, adjusting for age, ancestry, family history of PCa, and PCa screening history. Results: Subjects with more than 20 sexual partners in their lifetime had a decreased risk of PCa (OR 0.78, 95% CI 0.61–1.00) as did subjects who specifically had more than 20 female sexual partners (OR 0.72, 95% CI 0.56–0.94). By contrast, having had several male sexual partners appeared to confer some excess in risk of PCa. No association emerged for history of STIs and PCa but STIs prevalence was low. Conclusion: Our findings are in support of a role for the number of sexual partners in PCa development. The gender of sexual partners should be taken into account in future studies investigating this association.     

Evolution of sexually transmitted and sexually transmissible human herpesviruses

Herpesviruses occur in an impressively wide range of animals and are associated with various diseases. The numerous routes taken during hundreds of millions of years of evolution have contributed to their striking adaptability and success as pathogens. Herpesviruses share a distinct virion structure and are classified taxonomically into a single order, the Herpesvirales, which is divided into three families. The phylogenetic relationships among members of the most populous family, the Herpesviridae, which includes all nine human herpesviruses, are generally similar to those among their hosts, supporting the view that there has been a large degree of coevolution between virus and host. Three human herpesviruses (human cytomegalovirus, Kaposi's sarcoma-associated herpesvirus, and herpes simplex virus type 1) are classed as agents capable of sexually transmissible infection (StxI), and one (herpes simplex virus type 2) as an agent capable of sexually transmitted infection (STI). The evolutionary characteristics of these viruses are described.     

Expression of structural proteins in human female and male genital epithelia and implications for sexually transmitted infections

Men and women differ in their susceptibility to sexually transmittable infections (STIs) such as human immunodeficiency virus (HIV). However, a paucity of published information regarding the tissue structure of the human genital tract has limited our understanding of these gender differences. We collected cervical, vaginal, and penile tissues from human adult donors. Tissues were prepared with hematoxylin and eosin stains or immunofluorescence labeling of epithelial cell proteins and were analyzed for structural characteristics. Rhesus macaque genital tissues were evaluated to assess the use of this model for HIV/simian immunodeficiency virus transmission events. We found the stratified squamous epithelia of the male and female genital tract shared many similarities and important distinctions. Expression of E-cadherins, desmogleins 1/2, and involucrin was seen in all squamous epithelia, though expression patterns were heterogeneous. Filaggrin and a true cornified layer were markedly absent in female tissues but were clearly seen in all male epithelia. Desmogleins 1/2 were more consistent in the outermost strata of female squamous genital epithelia. Macaque tissues were similar to their respective human tissues. These initial observations highlight how male and female genital epithelia resemble and differ from one another. Further information regarding tissue structural characteristics will help to understand how STIs traverse these barriers to cause infection. This knowledge will be essential in future HIV pathogenesis, transmission, and prevention studies.     

Barriers to the use of modern contraceptives and implications for woman-controlled prevention of sexually transmitted infections in Madagascar

Globally, unplanned pregnancies and sexually transmitted infections (STIs) persist as significant threats to women's reproductive health. Barriers to the use of modern contraceptives by women might inhibit uptake of novel woman-controlled methods for preventing STIs/HIV. Use of modern contraceptives and perceptions and attitudes towards contraceptive use were investigated among women in Antananarivo, Madagascar, using qualitative research. The hypothetical acceptability of the diaphragm--a woman-controlled barrier contraceptive device that also holds promise of protecting against STIs/HIV--was assessed. Women consecutively seeking care for vaginal discharge at a public health clinic were recruited for participation in a semi-structured interview (SSI) or focus group discussion (FGD). Audiotaped SSIs and FGDs were transcribed, translated and coded for predetermined and emerging themes. Of 46 participating women, 70% reported occasional use of male condoms, mostly for preventing pregnancy during their fertile days. Although women could name effective contraceptive methods, only 14% reported using hormonal contraception. Three barriers to use of modern contraceptives emerged: gaps in knowledge about the range of available contraceptive methods; misinformation and negative perceptions about some methods; and concern about social opposition to contraceptive use, mainly from male partners. These results demonstrate the need for programmes in both family planning and STI prevention to improve women's knowledge of modern contraceptives and methods to prevent STI and to dispel misinformation and negative perceptions of methods. In addition, involvement of men will probably be a critical component of increased uptake of woman-controlled pregnancy and STI/HIV prevention methods and improved health.     

Laboratory diagnosis of sexually transmitted infections in chronic inflammatory diseases of the reproductive system

The complex clinico-laboratory examination of 120 infertile married couples and 120 couples with habitual miscarriage was made. For control, 96 healthy married couples were used. The microbiological risk factors of chronic pelvic inflammatory diseases were determined, namely: mixed parasitocenosis, including active anaerobic, viral and fungal components, as well as Chlamydia trachomatis. As shown in this study, metabolically active forms of chlamydial infection were characteristic of infertile married women and persistent forms of C. trachomatis, for pregnant women. At the same time chlamydial infection did not cause infertility in males. The use two of levels of laboratory tests for qualitative, quantitative and functional evaluation of parasitocenoses were proposed.     

The prevalence of sexually transmitted infections in Papua New Guinea: a systematic review and meta-analysis

Background

The potential for an expanded HIV epidemic in Papua New Guinea (PNG) demands an effective, evidence-based and locally-appropriate national response. As sexually transmitted infections (STIs) may be important co-factors in HIV transmission nationally, it is timely to conduct a systematic review of STI prevalences to inform national policy on sexual health and HIV/STI prevention.

Methodology/Principal Findings

We undertook a systematic review and meta-analysis of HIV and STI prevalences in PNG, reported in peer-reviewed and non-peer-reviewed publications for the period 1950–2010. Prevalence estimates were stratified by study site (community or clinic-based), geographic area and socio-demographic characteristics. The search strategy identified 105 reports, of which 25 studies (10 community-based; 10 clinic-based; and 5 among self-identified female sex workers) reported STI prevalences and were included in the systematic review. High prevalences of chlamydia, gonorrhoea, syphilis and trichomonas were reported in all settings, particularly among female sex workers, where pooled estimates of 26.1%, 33.6%, 33.1% and 39.3% respectively were observed. Pooled HIV prevalence in community-based studies was 1.8% (95% CI:1.2–2.4) in men; 2.6% (95% CI:1.7–3.5) in women; and 11.8% (95% CI:5.8–17.7) among female sex workers.

Conclusions/Significance

The epidemiology of STIs and HIV in PNG shows considerable heterogeneity by geographical setting and sexual risk group. Prevalences from community-based studies in PNG were higher than in many other countries in the Asia-Pacific. A renewed focus on national STI/HIV surveillance priorities and systems for routine and periodic data collection will be essential to building effective culturally-relevant behavioural and biomedical STI/HIV prevention programs in PNG.     

A versatile ODE approximation to a network model for the spread of sexually transmitted diseases

 We develop a moment closure approximation (MCA) to a network model of sexually transmitted disease (STD) spread through a steady/casual partnership network. MCA has been used previously to approximate static, regular lattices, whereas application to dynamic, irregular networks is a new endeavour, and application to sociologically-motivated network models has not been attempted. Our goals are 1) to investigate issues relating to the application of moment closure approximations to dynamic and irregular networks, and 2) to understand the impact of concurrent casual partnerships on STD transmission through a population of predominantly steady monogamous partnerships. We are able to derive a moment closure approximation for a dynamic irregular network representing sexual partnership dynamics, however, we are forced to use a triple approximation due to the large error of the standard pair approximation. This example underscores the importance of doing error analysis for moment closure approximations. We also find that a small number of casual partnerships drastically increases the prevalence and rate of spread of the epidemic. Finally, although the approximation is derived for a specific network model, we can recover approximations to a broad range of network models simply by varying model parameters which control the structure of the dynamic network. Thus our moment closure approximation is very flexible in the kinds of network models it can approximate. Received: 26 August 2001 / Revised version: 15 March 2002 / Published online: 23 August 2002 C.T.B. was supported by the NSF. Key words or phrases: Moment closure approximation – Network model – Pair approximation – Sexually transmitted diseases – Steady/casual partnership network     

Community perceptions and treatment-seeking behaviour regarding reproductive tract infections including sexually transmitted infections in Lao PDR: a qualitative study

Creating community awareness of reproductive tract infections (RTI), including sexually transmitted infections (STI), and how to prevent them is essential to minimize their spread. Data on people's views about RTI/STI are entirely lacking in Laos. The aim of this study was thus to explore people's perceptions, treatment-seeking behaviour and understanding of information about RTI/STI, in urban and rural communities in two provinces in Laos. Fourteen focus group discussions and 20 in-depth interviews were held with 76 women and 56 men, selected purposively to provide diversity of socio-demographic backgrounds. Qualitative content analysis was employed for the data analysis. The major finding was that both male and female participants had a variety of misconceptions about the causes and symptoms of RTI/STI and their cure, and a reluctance to seek health care, which could cause delay in appropriate diagnosis and treatment. The most common treatment-seeking behaviour was self-medication through private pharmacies, following advice mostly given by friends and drug sellers. The main reasons for not going to health facilities were fear of social discrimination or shyness of genital examination. Complaints were also made about clinicians' negative attitudes towards 'dirty disease'. Although condom use was mentioned as a way to prevent RTI/STI, an unwillingness to use condoms was commonly expressed. The main media sources of RTI/STI information were radio and television, and access to health information was more difficult in rural areas. The health messages provided were mostly understood, except for some technical terms. The findings indicate that strengthening health education and promotion through interventions at the community level is recommended to improve quality of RTI/STI management. Health education messages should be more accessible in rural areas. There is also an urgent need to improve communication between RTI/STI patients and clinicians.     

Morbidity in sexually transmitted infections in the Republic of North Ossetia-Alania and the improvement of epidemiological surveillance

The present situation in sexually transmitted diseases (STD) in the Republic of North Ossetia-Alania is characterized as unfavorable. Morbidity in different nosological forms has been found to show different tendencies. The causes of elevated morbidity in STD observed in recent years have social, economic, psychological, ethical and moral, rather than medical character. The main trends in the improvement of epidemiological surveillance on STD have been determined.     

Modelling sexually transmitted infections: the effect of partnership activity and number of partners on R0

We model a sexually transmitted infection in a network population where individuals have different numbers of partners, separated into steady and casual partnerships, where the risk of transmission is higher in steady partnerships. An individual's number of partners of the two types defines its degree, and the degrees in the community specify the degree distribution. For this structured network population a simple model for disease transmission is defined and the basic reproduction number R0 is derived, R0 being a size-biased (i.e. biasing individuals with many partners) average number of new infections caused by individuals during the early stages of the epidemic. First a homosexual population is considered and then a heterosexual population. The heterosexual model is fitted to data from a census survey on sexual activity from the Swedish island of Gotland. The main empirical finding is that, for relevant transmission rates, the effect that so-called superspreaders have on R0 is over-estimated when not admitting for different types of partnerships.     

Immune anticipation of mating in Drosophila: Turandot M promotes immunity against sexually transmitted fungal infections

Although it is well known that mating increases the risk of infection, we do not know how females mitigate the fitness costs of sexually transmitted infections (STIs). It has recently been shown that female fruitflies, Drosophila melanogaster, specifically upregulate two members of the Turandot family of immune and stress response genes, Turandot M and Turandot C (TotM and TotC), when they hear male courtship song. Here, we use the Gal4/UAS RNAi gene knockdown system to test whether the expression of these genes provides fitness benefits for females infected with the entomopathogenic fungus, Metarhizium robertsii under sexual transmission. As a control, we also examined the immunity conferred by Dorsal-related immunity factor (Dif), a central component of the Toll signalling pathway thought to provide immunity against fungal infections. We show that TotM, but not TotC or Dif, provides survival benefits to females following STIs, but not after direct topical infections. We also show that though the expression of TotM provides fecundity benefits for healthy females, it comes at a cost to their survival, which helps to explain why TotM is not constitutively expressed. Together, these results show that the anticipatory expression of TotM promotes specific immunity against fungal STIs and suggest that immune anticipation is more common than currently appreciated.