The genus Chlamydiae encompasses a unique class of obligate intracellular bacteria that can cause disease in a wide range of animals. In humans, Chlamydia trachomatis infections are common and are frequently observed in diseases of the eye, genital and respiratory tracts. Prevalent worldwide, Chlamydia infections can progress to chronic inflammatory sequellae and are the leading cause of curable sexually transmitted disease and preventable blindness. After falling in the face of intensified control efforts, case notifications of sexually transmitted Chlamydia in many countries are rising. In many jurisdictions, this unprecedented rise of Chlamydia case notifications has occurred after the introduction of wide spread control programs, and has been discussed to be a result of either increased testing volume, improvements to testing technologies, changes in sexual behaviour, or increased reinfection rates brought about by deleterious effects of treatment on acquired immunity. This thesis seeks to answer the question of why observed Chlamydia case notifications have rebounded? I have attempted to answer this question using simple dynamical models of Chlamydia transmission framed from immunological and epidemiological perspectives. Model structures are drawn from frameworks previously used for studying sexually transmitted infections, and represent a combination of theoretical and data-oriented formulations, as well as different (hierarchical) ecological scales. The results of this thesis highlight that increased testing volumes, rather than changes in the sensitivity and specificity of testing technologies, sexual behaviour, or truncated immunological responses brought about by treatment can explain the increase in observed chlamydia case notifications, and that simple explanations for these observed rates appear to have been dismissed in favor of an increase to the underlying prevalence. In addition to providing insights into current epidemiological trends, this thesis has also been able to produce significant insights into the natural history of chlamydial infection. In particular, the phenotype of an individual's immunobiology that results from multiple chlamydial infections suggests that longer periods between initial and repeat infection may increase an individual's chlamydial load, their duration of infection, as well as non-intuitively the formation of protective immunity, persistent infection, and the potential for immunopathogenesis. Additional population-scale analyses in this thesis also suggest the existence of a period of immunity that is, on average, much longer lasting than currently discussed in contemporary literature. The results of this research outline a potential way forward through filling several gaps in the immunological and epidemiological understanding of Chlamydia infections that involves both reviewing existing data as well as continued research using "systems science" approaches.

This thesis comprises a detailed analysis of sexual risk behavior among female sex workers participating in a prospective cohort study in Mombasa, Kenya between 1993 and 2007. To determine whether high-risk behavior has decreased over time, I examined trends in and associations with condom use and partner numbers at enrolment and over follow-up using multinomial logistic regression. While condom use increased among women enrolling into the cohort, women reduced partner numbers, rather than increasing condom use, over cohort visits. Workplace, charge for sex, duration of sex work, alcohol use, pregnancy and illness were all predictors of condom use. To evaluate the extent to which HIV risk estimates were affected by loss to follow-up, I investigated associations between sexual risk behavior, loss to follow-up, and HIV acquisition, using competing risks regression. Women reporting unprotected sex with multiple partners had the highest risk for HIV infection, and were also most likely to remain in the cohort. Finally, I used Andersen-Gill modeling to assess the impact of sexual risk behaviors on acquisition of sexually transmitted infections (STI) including gonorrhea, non-specific cervicitis, and trichomoniasis. While incident gonorrhea was closely associated with recent sexual risk behavior, incident trichomoniasis was not. Both conditions had high hazards for recurring in a 90-day window after a prior diagnosis. Non-specific cervicitis was demonstrated to be a chronic, relapsing condition associated with protected sex with multiple partners (possibly due to more frequent condom use) and with known biologic risk factors (i.e., pregnancy, hormonal contraceptive use, cervical ectopy, and genital ulcer disease). Overall, these analyses have led to a better understanding of how different sexual behavior patterns are associated with adverse outcomes, including HIV and STI acquisition, and identified specific factors associated with high-risk sexual behavior that may be amenable to intervention.

This thesis comprises a detailed analysis of sexual risk behavior among female sex workers participating in a prospective cohort study in Mombasa, Kenya between 1993 and 2007. To determine whether high-risk behavior has decreased over time, I examined trends in and associations with condom use and partner numbers at enrolment and over follow-up using multinomial logistic regression. While condom use increased among women enrolling into the cohort, women reduced partner numbers, rather than increasing condom use, over cohort visits. Workplace, charge for sex, duration of sex work, alcohol use, pregnancy and illness were all predictors of condom use. To evaluate the extent to which HIV risk estimates were affected by loss to follow-up, I investigated associations between sexual risk behavior, loss to follow-up, and HIV acquisition, using competing risks regression. Women reporting unprotected sex with multiple partners had the highest risk for HIV infection, and were also most likely to remain in the cohort. Finally, I used Andersen-Gill modeling to assess the impact of sexual risk behaviors on acquisition of sexually transmitted infections (STI) including gonorrhea, non-specific cervicitis, and trichomoniasis. While incident gonorrhea was closely associated with recent sexual risk behavior, incident trichomoniasis was not. Both conditions had high hazards for recurring in a 90-day window after a prior diagnosis. Non-specific cervicitis was demonstrated to be a chronic, relapsing condition associated with protected sex with multiple partners (possibly due to more frequent condom use) and with known biologic risk factors (i.e., pregnancy, hormonal contraceptive use, cervical ectopy, and genital ulcer disease). Overall, these analyses have led to a better understanding of how different sexual behavior patterns are associated with adverse outcomes, including HIV and STI acquisition, and identified specific factors associated with high-risk sexual behavior that may be amenable to intervention.

The genus Chlamydiae encompasses a unique class of obligate intracellular bacteria that can cause disease in a wide range of animals. In humans, Chlamydia trachomatis infections are common and are frequently observed in diseases of the eye, genital and respiratory tracts. Prevalent worldwide, Chlamydia infections can progress to chronic inflammatory sequellae and are the leading cause of curable sexually transmitted disease and preventable blindness. After falling in the face of intensified control efforts, case notifications of sexually transmitted Chlamydia in many countries are rising. In many jurisdictions, this unprecedented rise of Chlamydia case notifications has occurred after the introduction of wide spread control programs, and has been discussed to be a result of either increased testing volume, improvements to testing technologies, changes in sexual behaviour, or increased reinfection rates brought about by deleterious effects of treatment on acquired immunity. This thesis seeks to answer the question of why observed Chlamydia case notifications have rebounded? I have attempted to answer this question using simple dynamical models of Chlamydia transmission framed from immunological and epidemiological perspectives. Model structures are drawn from frameworks previously used for studying sexually transmitted infections, and represent a combination of theoretical and data-oriented formulations, as well as different (hierarchical) ecological scales. The results of this thesis highlight that increased testing volumes, rather than changes in the sensitivity and specificity of testing technologies, sexual behaviour, or truncated immunological responses brought about by treatment can explain the increase in observed chlamydia case notifications, and that simple explanations for these observed rates appear to have been dismissed in favor of an increase to the underlying prevalence. In addition to providing insights into current epidemiological trends, this thesis has also been able to produce significant insights into the natural history of chlamydial infection. In particular, the phenotype of an individual's immunobiology that results from multiple chlamydial infections suggests that longer periods between initial and repeat infection may increase an individual's chlamydial load, their duration of infection, as well as non-intuitively the formation of protective immunity, persistent infection, and the potential for immunopathogenesis. Additional population-scale analyses in this thesis also suggest the existence of a period of immunity that is, on average, much longer lasting than currently discussed in contemporary literature. The results of this research outline a potential way forward through filling several gaps in the immunological and epidemiological understanding of Chlamydia infections that involves both reviewing existing data as well as continued research using "systems science" approaches.

This thesis explores incidence rates of sexually transmitted infections (STIs) among minority group teenagers in the United States and among adults aged 20-34 in the U.S. and in China. The focus is on trends and patterns in the United States compared to those in China. Research questions include whether or not the early onset of sexual activity is directly related to the incidence of STI transmission among Americans. The Chinese analysis enables addressing the question of whether or not a hidden epidemic exists in China with regard to STI transmission rates. The thesis involves three separate analyses including a comparative study of teens (age 15-19) and adults (age 20-44) in the United States, a comparative study of adults aged 20-44 in the United States and China, and a comparative analysis of urine-based results versus self-reported responses among the Chinese adults. The use of logistic regression is employed in order to model the odds of the risk of transmission among the different groups. The results from this thesis indicate that early onset of sexual activity is indeed a risk factor for young minority group members in the United States in terms of the bacterial infections. The analysis of American adults revealed that women who have college educations and who are not minority group members are at risk of contracting viral infections with more frequency. Finally, a hidden epidemic among Chinese women was detected with respect to the bacterial infections. It is important to study these trends within the U.S. and abroad in China for many reasons. First and foremost, young adults are the most heavily impacted in the United States. This population should be focused on as many of the infections discussed may lead to lifelong difficulties (including infertility) if left untreated. Also, with respect to China, a large proportion of those who are infected do not know they are. Again, these infections may lead to many complications and Chinese women are at an increased risk because many are infected unknowingly due to the behavior of their partner/spouse. Finally, sexually transmitted infections amplify the transmission rates of HIV/AIDS and should be studied specifically for this reason if none other.

Background: The purpose of this secondary data analysis was to determine the prevalence of sexually transmitted and blood-borne infections (STBBI) and to examine the role of survival sex in sexual risk among street-involved youth in Winnipeg, Manitoba. Methods: Between 1999 and 2003, 743 Winnipeg street youth were interviewed in three separate cohorts as part of a national multi-centred study by the Public Health Agency of Canada. Results: Among the 673 Winnipeg street youth who responded to questions relating to survival sex, 26.3% reported they had engaged in survival sex. Females and Aboriginal youth were at greatest risk for sex trade involvement. Youth engaged in survival sex were diagnosed with significantly higher rates of STBBI; experienced greater amounts of abuse; and were at greater risk for participating in high risk sexual behaviours compared to their non-sex trade counterparts. Conclusion: Gender specific, culturally appropriate, and youth oriented prevention and intervention strategies are urgently required to reduce the prevalence of STBBI and survival sex among this at-risk population.

Background: The purpose of this secondary data analysis was to determine the prevalence of sexually transmitted and blood-borne infections (STBBI) and to examine the role of survival sex in sexual risk among street-involved youth in Winnipeg, Manitoba. Methods: Between 1999 and 2003, 743 Winnipeg street youth were interviewed in three separate cohorts as part of a national multi-centred study by the Public Health Agency of Canada. Results: Among the 673 Winnipeg street youth who responded to questions relating to survival sex, 26.3% reported they had engaged in survival sex. Females and Aboriginal youth were at greatest risk for sex trade involvement. Youth engaged in survival sex were diagnosed with significantly higher rates of STBBI; experienced greater amounts of abuse; and were at greater risk for participating in high risk sexual behaviours compared to their non-sex trade counterparts. Conclusion: Gender specific, culturally appropriate, and youth oriented prevention and intervention strategies are urgently required to reduce the prevalence of STBBI and survival sex among this at-risk population.

Thesis (M.S.H.P.) PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / IMPORTANCE: With greater access to health care through health care reform it is important to know if quality of care for similar complaints differs across clinical settings. OBJECTIVE: Develop and pilot a chart review instrument to measure quality of care for patients presenting with urethritis and vaginitis. METHODS: List of sexually transmitted infection (STI) quality of care measures was reviewed by a panel of five STI experts representing Emergency Department (ED), Obstetrics/Gynecology (Ob/Gyn), Family Medicine (FM), Primary Care (PC) and Infectious Disease. Panel members grouped each measure into “standard” or “exceeds standard of care” in evaluation and management of male patients with penile discharge/dysuria or female patients with vaginal discharge. The chart review instrument was piloted on 50 charts per gender from the STI Clinic and matched charts, by patient presenting complaint, age, gender, and visit date, from PC, FM, ED, and Ob/Gyn (for vaginal discharge) in the same large safety-net hospital in Massachusetts. RESULTS: Twenty-four and 34 final measures in male and female patients, respectively, were selected on plurality of expert panel member’s categorization into “standard of care”. Measures were grouped into 7 clinical domains: history, examination, laboratory testing, additional screening, assessment, treatment, and counseling. Performance on the 7 domains ranged from 3.16-4.36 on male patients and 3.17-4.40 on female patients, with the highest scores in the STI Clinic. However, each clinical setting had particular documentation strengths and weaknesses: STI Clinic scored higher on laboratory testing, additional screening, and counseling, but scored lower on examination and assessment; ED scored higher on examination and treatment; PC and FM scored higher on laboratory testing for male patients and on examination and treatment for female patients; Ob/Gyn scored higher on treatment. All sites other than the STI Clinic scored poorly on additional screening and counseling. CONCLUSIONS: An instrument to discern standard of care and identify strengths and weaknesses in specific domains of clinical documentation for patients presenting with STI complaints can be rapidly developed and implemented to evaluate quality of care across care settings. Further research is needed on whether these findings can be integrated into site-specific quality improvement processes and linked to cost analyses. / 2031-01-01

Master of Public Health - MPH / The notification and treatment of sexual partner(s) is a key element in the prevention and control of sexually transmitted infections (STIs). Partner notification interrupts the chain of STI transmission, prevents STI complications and long-term sequelae in the sexual partner(s), and also prevents re-infection of the treated index patient. Partner notification is a recognized component of the syndromic management of STIs in Namibia and yet the partner notification rates in the country remain low - as low as 7% in the district of Windhoek currently. In this district, which has the highest number of STIs cases in Namibia, the specific factors that hinder partner notification have not yet been documented. This study sought to investigate the perceived and experienced barriers to partner notification amongst STI patients attending an urban primary health center in the district. An explorative, qualitative study with eight patients (four males and four females), aged 16 years and over, who presented with a new/recurrent episode or a STI follow up was conducted. The participants were purposively selected with the aid of the deputy nurse in charge of the health center after agreeing to take part in the study. The patients were asked about what they felt were personal, partner-relationship and health services related factors that hindered partner notification. Three health workers working at the health center served as key informants and were asked about barriers to partner notification based on their experience of delivering preventative and curative STI - related services over the past three or more years. Interviews with both patients and key informants were conducted in the health facility, recorded and later transcribed. Content analysis of the transcribed data was conducted to identify recurring themes across the different interviews. The results of the study suggest that the partner notification strategy was not functioning optimally as a result of a number of inter-twined factors. The factors can be categorized into personal barriers, partner-relationship dynamics and health services related barriers. The study found that participants considered there were barriers to partner notification across all these three categories. Commonly reported barriers included the stigma associated with STIs and the cultural and religious norms that do not promote discussion of topics related to sex and sexuality in general. Other barriers such as gender inequality, the fear of a partner's reaction to the notification, feelings of guilt associated with infidelity, the lack of communication between partners and the inability to locate partner(s) were highlighted by participants. Barriers associated with the health services included the lack of health education about the importance of partner notification, the absence of thorough risk reduction counseling, the current method of partner notification that is being utilized and the negative attitudes of health workers. It is suggested that having a greater understanding of these barriers and how to work with them in a health education or counseling sessions will allow health workers to address them more directly with their patients and in turn, hopefully improve the management and outcomes of partner notification strategies in the STI prevention and control program in the Windhoek district and potentially other districts in Namibia.

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