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 review of sexual education in the United States broadly defines the two most common approaches in sexual education seen in this country today. I cover the status of certain sexual behaviors and risks amongst the teenage population in the U.S. and specifically cover reported sexual activity in high school students and overall data on teen pregnancies and sexually transmitted infections (STIs). This work specifically looks at Maine, California, Texas, Maryland, North Carolina, and New Mexico to highlight the variety of state policies concerning sexual education and the differences in teenage sexual behaviors that exist within each of those six states. A description of how cultural influences can affect a young person’s sexual behavior is also given. In the final discussion section of this paper I have emphasized the need for more comprehensive sexual education programs in the United States and the importance of providing culturally sensitive programs in order to continue the fight against teenage pregnancy and STI rates in adolescents.

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.

Background: Sexually transmitted diseases (STDs) have been a increasing problem worldwide with an estimation of 340 million new cases each year. STDs are one of the top five reasons of seeking health care in the developing countries. Aim: The aim was to investigate the knowledge, attitudes and beliefs regarding STDs among young adults in two vocational schools in Ho Chi Minh City, Vietnam and also compare the genders regarding the issues. Method: A descriptive and comparative study was used. The 455 students between the age of 15 and 24, both male and female, participated voluntarily to answer a questionnaire. Dorothea Orem’s self-caring theory was provided as theoretical framework. Results: The students showed a low knowledge regarding STDs. Small differences between the genders could be seen regarding knowledge where the males had a higher knowledge regarding symptoms of STDs. Conclusions: The adolescents had lack of knowledge about STDs and no greater difference between genders have been shown. The traditional attitudes must change and follow the development of Vietnam. Further research should be performed to find out if there is any difference between students in rural and central areas of Vietnam.

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.

Thesis ( Ph.D.) -- University of Texas at Arlington, 2008.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 169-185). Available also in a digital version from Dissertation Abstracts.

Bachelor's thesis. / Format: PDF. Bibl.