Catherine Theresa Desmarais

The study is an inquiry of sexual networks in the Johanne Marange apostolic community. The study is a conceptual shift in the study of HIV transmission, with focus moving beyond the individual and beyond the principles of desire, pleasure and procreation to a study of sexual networks which are social structures. The study identifies the type of sexual networks and further investigates the determinants of sexual networks in Marange community. Sexual networks are simply webs of sexual relations in a community or society and these webs of relations act as transmission highways for HIV. The study discusses all the complex interactions between the domain of society that is religion, culture, history and environment of the Marange community and uncovers how these aspects of society have influenced the shape and structure of sexual networks in the community. The study also emphasizes the importance of understanding sexual network structure as it influences the efficiency of HIV transmission and aims to contribute to a better understanding of sexual networks and HIV transmission.

In this thesis I set out to further our understanding of two broad questions, 1) why it is that sexual selection favours the evolution of particular traits and 2) why do the patterns of sexual selection on such traits differ between groups and populations? Specifically, I focused on the role that variation in intrasexual competitive structure, the non-random distribution of socio-competitive environments across individuals, plays in shaping variation in the operation of sexual selection both within and across populations. I explore the roles of three main determinants of competitive structure, namely; population structure, polyandry and non-random variation in the distribution of the intensity of competition. To achieve this, I used a combination of empirical and theoretical tools, using the model system Red junglefowl, Gallus gallus. Throughout this thesis I both develop and employ network quantitative tools as a framework to describe variation in intrasexual competitive structure. Overall, this thesis demonstrates a complex relationship between competitive structure and the operation of sexual selection. This structure can modify the strength and direction of sexual selection operating on phenotypic traits, obscure the operation of selection at the population level and influence the relative roles of pre- and post-copulatory sexual selection. Furthermore, this thesis explores how differences in local ecology can shape competitive structure itself and in turn shape sexual selection. In doing so, this thesis sheds some light on the role that variation in competitive structure may play in shaping the operation of sexual selection both within and between populations and generating the great diversity in sexually-selected traits and behaviours between populations.

Adolescents are disproportionately affected by a wide range of STDs due to high level of personal risk behaviors and poor access to STD prevention services. As documented in numerous previous studies, STDs could lead to many serious consequences to adolescents’ health and the overall well being of society. One prominent concern is that STDs increase adolescent’s risk in acquiring HIV infection. Among all STDs, Chlamydia is the most prevalent in adolescents as well as in the general population. No previous studies have attempted to examine the social interaction of adolescent population heavily affected by Chlamydia. In this study, we would like to take a step forward to identify the difference in behavioral risk level between Chlamydia positive and negative adolescent social network and to describe any impacts of these groups on the transmission of other STDs using social network analysis of data collected from adolescent population in Dekalb County, Georgia. The results indicated highest behavioral risk in the negative girl index respondents’ contacts followed by those of positive boys, positive girls and finally negative boys. However STD prevalence in the contacts among these different groups did not follow the same pattern. Prevalence of STD is highest in the negative girls’ contact group followed by that of positive boys, negative boys; and interestingly positive boys’ contacts exhibit the lowest STD rate. As informed by the results, the presence of infection is not a sufficient indicator of risks; thus, network characteristic was also examined to accurately determine transmission dynamics in this population. Social and sexual network structures among these four different index groups and their contacts suggested low level of STD transmission.

Gonorrhea, caused by the human pathogen Neisseria gonorrhoeae, is a severe public health problem worldwide with more than 82 million new infections each year. N. gonorrhoeae is transmitted by sexual contact and primarily causes urogenital mucosal infections in men and women. Left untreated, this infection may cause severe complications, especially in females. Eye infections of the newborn can occur. Gonorrhea infections enhance HIV transmission. The highly prevalent antibiotic resistance and the emergence of new drug resistances render treatment of the infections increasingly difficult. Close monitoring of antimicrobial susceptibility of this pathogen is crucial, and enhanced knowledge of molecular mechanisms of gonococcal antimicrobial resistance is urgently needed. There are no vaccines available against N. gonorrhoeae. Control of gonorrhea relies on comprehensive strategies which can be better formulated by understanding, at molecular levels, how N. gonorrhoeae is transmitted in communities. My research aimed to illustrate the severe burden of antimicrobial resistance in N. gonorrhoeae temporally and geographically in China and to reveal the molecular mechanisms of antibiotic resistance particularly the development of reduced susceptibility to ceftriaxone in N. gonorrhoeae isolates. To determine specific strain distributions, N. gonorrhoeae isolates were characterized using molecular typing methods such as a modified porB-based typing scheme and the N. gonorrhoeae Multi-Antigen Typing (NG-MAST) method, compared to traditional epidemiological approaches. The ultimate goal was to provide information for better formulating disease control strategies for gonorrhea. In this research, male patients with gonorrhea and their sex partners were recruited in Shanghai (2005 and 2008) and in Urumchi (2007-2008), China. Epidemiological information pertaining to sexual contacts was collected. N. gonorrhoeae isolates were investigated for their antimicrobial susceptibility. Molecular mechanisms of antimicrobial resistance were explored by analysis of potential resistant determinants (gyrA, parC, porB, mtrR, ponA and penA). The molecular data were combined with bioinformatic analysis and traditional epidemiological data. High percentages of N. gonorrhoeae isolates (11% - 19% in Shanghai, 4.5% in Urumchi) exhibited reduced susceptibility to ceftriaxone (MICs = 0.125-0.25 mg/L), the first line drug recommended for the treatment of gonorrhea in China. The majority of isolates (>98%) were susceptible to spectinomycin, an alternative regimen for gonorrhea treatment; however, the proportion of isolates having intermediate levels of susceptibility increased from 1.9% in 2005 to 9.9% in 2008. The majority of isolates tested were resistant to penicillin (80% - 93%), tetracycline (56% - 65%) and ciprofloxacin (98% - 100%). Plasmid-mediated resistance in N. gonorrhoeae isolates were highly prevalent (51% - 79%) in Shanghai and Urumchi. Analysis of 60 clinical isolates revealed that reduced susceptibility to ceftriaxone is mediated by porB1b allele and is associated with specific mutations in penicillin binding protein 2 and in the DNA binding and dimerization domains of MtrR. Penicillin binding protein 1 is not involved in reduced susceptibility to ceftriaxone. Although mutation patterns in quinolone resistant determinant regions (QRDRs) varied, the majority of ciprofloxacin resistant isolates had double mutations in GyrA (S91F and D95G/A/N) and most isolates also carried a S87R/N mutation in ParC. The presence of mutations in the QRDR of ParC is correlated with elevated ciprofloxacin MICs. A modified porB-based molecular typing scheme was developed and involved ~82% of the DNA sequence of gonococcal porB. This typing method proved to have high discriminatory ability (index of discrimination = 0.93 0.96), and was cost effective and easy to perform as compared to the NG-MAST analysis. Using the modified porB-based typing method, N. gonorrhoeae isolates were reliably differentiated, and transmission clusters were identified. Molecular epidemiology using the porB-based method confirmed direct sexual connections and identified sexual networks otherwise unrevealed by the patient self-reporting or traditional case-tracing methods.

Gonorrhea, caused by the human pathogen Neisseria gonorrhoeae, is a severe public health problem worldwide with more than 82 million new infections each year. N. gonorrhoeae is transmitted by sexual contact and primarily causes urogenital mucosal infections in men and women. Left untreated, this infection may cause severe complications, especially in females. Eye infections of the newborn can occur. Gonorrhea infections enhance HIV transmission. The highly prevalent antibiotic resistance and the emergence of new drug resistances render treatment of the infections increasingly difficult. Close monitoring of antimicrobial susceptibility of this pathogen is crucial, and enhanced knowledge of molecular mechanisms of gonococcal antimicrobial resistance is urgently needed. There are no vaccines available against N. gonorrhoeae. Control of gonorrhea relies on comprehensive strategies which can be better formulated by understanding, at molecular levels, how N. gonorrhoeae is transmitted in communities. My research aimed to illustrate the severe burden of antimicrobial resistance in N. gonorrhoeae temporally and geographically in China and to reveal the molecular mechanisms of antibiotic resistance particularly the development of reduced susceptibility to ceftriaxone in N. gonorrhoeae isolates. To determine specific strain distributions, N. gonorrhoeae isolates were characterized using molecular typing methods such as a modified porB-based typing scheme and the N. gonorrhoeae Multi-Antigen Typing (NG-MAST) method, compared to traditional epidemiological approaches. The ultimate goal was to provide information for better formulating disease control strategies for gonorrhea. In this research, male patients with gonorrhea and their sex partners were recruited in Shanghai (2005 and 2008) and in Urumchi (2007-2008), China. Epidemiological information pertaining to sexual contacts was collected. N. gonorrhoeae isolates were investigated for their antimicrobial susceptibility. Molecular mechanisms of antimicrobial resistance were explored by analysis of potential resistant determinants (gyrA, parC, porB, mtrR, ponA and penA). The molecular data were combined with bioinformatic analysis and traditional epidemiological data. High percentages of N. gonorrhoeae isolates (11% - 19% in Shanghai, 4.5% in Urumchi) exhibited reduced susceptibility to ceftriaxone (MICs = 0.125-0.25 mg/L), the first line drug recommended for the treatment of gonorrhea in China. The majority of isolates (>98%) were susceptible to spectinomycin, an alternative regimen for gonorrhea treatment; however, the proportion of isolates having intermediate levels of susceptibility increased from 1.9% in 2005 to 9.9% in 2008. The majority of isolates tested were resistant to penicillin (80% - 93%), tetracycline (56% - 65%) and ciprofloxacin (98% - 100%). Plasmid-mediated resistance in N. gonorrhoeae isolates were highly prevalent (51% - 79%) in Shanghai and Urumchi. Analysis of 60 clinical isolates revealed that reduced susceptibility to ceftriaxone is mediated by porB1b allele and is associated with specific mutations in penicillin binding protein 2 and in the DNA binding and dimerization domains of MtrR. Penicillin binding protein 1 is not involved in reduced susceptibility to ceftriaxone. Although mutation patterns in quinolone resistant determinant regions (QRDRs) varied, the majority of ciprofloxacin resistant isolates had double mutations in GyrA (S91F and D95G/A/N) and most isolates also carried a S87R/N mutation in ParC. The presence of mutations in the QRDR of ParC is correlated with elevated ciprofloxacin MICs. A modified porB-based molecular typing scheme was developed and involved ~82% of the DNA sequence of gonococcal porB. This typing method proved to have high discriminatory ability (index of discrimination = 0.93 0.96), and was cost effective and easy to perform as compared to the NG-MAST analysis. Using the modified porB-based typing method, N. gonorrhoeae isolates were reliably differentiated, and transmission clusters were identified. Molecular epidemiology using the porB-based method confirmed direct sexual connections and identified sexual networks otherwise unrevealed by the patient self-reporting or traditional case-tracing methods.

From the early 1990s, rates of HIV infection increased dramatically in South Africa and by the early 2000s, AIDS emerged as the main cause of death for adult South Africans. During the first half of the 2000s, the South African government’s response to this crisis was inadequate, marked by denial and delays in implementing prevention and treatment, resulting in thousands of preventable deaths. Yet, apart from the challenges posed by the predominantly urban-based Treatment Action Campaign (TAC), the absence of a social response to this crisis is notable, especially in rural settings. This scenario forms the broad backdrop to this ethnographic study that draws on participant observation and interviews undertaken over a three-year period (2002-2005) in KwaBomba village previously in the Gazankulu Homeland, now located in the Bushbuckridge municipality of the South African lowveld. An ethnographic perspective provides an intimate vantage point from which to view peoples’ experiences of the AIDS epidemic and their responses in context. This perspective draws attention to gaps in public health and biomedical understandings of the epidemic and suggests alternatives to these understandings. In Bushbuckridge, mortality and morbidity due to AIDS became visible in the late 1990s and early 2000s. Households were incapable of dealing with the burden of illness and death while the health services were often unwilling and ill-prepared. HIV prevention campaigns based on individual behaviour change were not well suited to a context in which HIV spread through sexual networks. Despite widespread awareness of the threat of AIDS, the disease was subjected to public censorship and AIDS suffering was concealed. Public discourses of AIDS were hidden within gossip and rumour and articulated as witchcraft suspicions and accusations. Although these discourses appear to deny and suppress the reality of AIDS, I suggest that they are active attempts to deal with the AIDS crisis: gossip and rumour allocate blame and construct a local epidemiology through which the epidemic can be surveilled; interpreting AIDS as witchcraft creates the possibility of avenging untimely death. These discursive forms are critical in informing individual and social responses to the AIDS epidemic. While the absence of public acknowledgement of AIDS as a cause of illness and death suggests denial and fatalism and appears to limit public action, subaltern discourses create shared secrets to manage the AIDS epidemic at the local level. Furthermore, these discourses may constitute a form of resistance against biomedical models of causality. Ethnographic enquiry at the local level offers a nuanced understanding of social responses to the AIDS epidemic. By examining forms of expression that lie outside the domain of public health, the thesis reveals how these constitute significant forms of social action in response to the epidemic. / Thesis (PhD)--University of Pretoria, 2012. / Anthropology and Archaeology / unrestricted

This thesis sought to develop an agent-based model that replicates the formation of social and sexual partnerships in real-world settings with an eventual aim of revealing the main drivers of the HIV pandemic in a closed mixed society. Agent-based modelling is a computational modelling approach that allows for the simulation of the actions and interactions of autonomous agents, with the eventual objective of disovering global effects on the system. This modelling technique is less dependent on generalisations and does not average out the behaviour of individuals. Sexual partnerships formed in the model goes through the process of dating, courting and has a chance of developing into marriage as well as the possibility of breaking up or undergo divorce. Sexual partnership formation is based on a likeability index calculated using aspiration, attractiveness and age. Over and above the the sexual relationships we include commercial sex work. Commercial sex work depends mainly on the availability of female sex workers and their clients. We superimpose the spread of HIV on the social and sexual network model. Results from the model reveal that saturation of HIV prevalence is driven by the social and sexual network structure, behaviour change as well as biologic factors. Excluding commercial sex work in the model resulted in a decrease in HIV prevalence and incidence. Dense social networks resulted in a dense sexual network which consequently increased HIV incidence. A change in the infection probability per coital act contributed significantly to a change in incidence and prevalence levels. Model results also show that enrolling all HIV positive agents on antiretroviral therapy (ART) as from 2016 simulation year will help in curbing HIV transmission if zero dropout rate from ART is assumed. Therefore, on concomitant action to avoid dropouts from ART is necessary if full benefits of introducing ART to all HIV positive individuals are to be realised. / Operations Management / D.Phil. (Operations Research)

Yes / With the aim of targeting high-risk hidden heterosexual young people for Chlamydia trachomatis (CT) testing, an innovative web-based screening strategy using Respondent Driven Sampling (RDS) and home-based CT testing, was developed, piloted and evaluated. Two STI clinic nurses encouraged 37 CT positive heterosexual young people (aged 16-25 years), called index clients, to recruit peers from their social and sexual networks using the web-based screening strategy. Eligible peers (young, living in the study area) could request a home-based CT test and recruit other peers. Twelve (40%) index clients recruited 35 peers. Two of these peers recruited other peers (n = 7). In total, 35 recruited peers were eligible for participation; ten of them (29%) requested a test and eight tested. Seven tested for the first time and one (13%) was positive. Most peers were female friends (80%). Nurses were positive about using the strategy. The screening strategy is feasible for targeting the hidden social network. However, uptake among men and recruitment of sex-partners is low and RDS stopped early. Future studies are needed to explore the sustainability, cost-effectiveness, and impact of strategies that target people at risk who are not effectively reached by regular health care.