Les clients de TS sont considérés comme un groupe à risque de VIH et aussi agiraient comme un « pont de transmission » entre les TS et les femmes de la population générale. En dépit de leurs comportements sexuels à risque, les clients de TS ont été rarement étudiés. En conséquence, les objectifs spécifiques de cette thèse étaient : 1) estimer la prévalence du VIH, de la syphilis, du VHS-2 (virus de l’herpès simplex et 2) des facteurs de risque associés chez les clients de TS en Haïti, 2) examiner les déterminants de l’intention d’utilisation du condom, et 3) estimer la prévalence des comportements de violence et ses conséquences. Pour ce faire, une enquête transversale a été effectuée en 2006 auprès de 378 clients fréquentant les milieux de prostitution de St-Marc et de Gonaïves, en Haïti. Un questionnaire structuré ainsi que des échantillons de sang séché sur papier filtre ont été utilisés pour la collecte de données comportementales et biologiques. Notre premier article a montré une prévalence élevée du VIH et des ITS chez les clients. Ces hommes avaient plusieurs partenaires sexuelles avec lesquelles l’utilisation du condom variait. Les clients qui avaient déjà consommé de la marijuana, pratiquaient le vaudou, avaient des antécédents d’ITS ou étaient infectés par le VHS-2, avaient plus de chances d’être positifs au VIH. Le fait d’habiter Gonaïves, de ne pas être protestant, d’être employé et d’avoir déjà essayé la marijuana était associé à l’infection à la syphilis. Tandis que les clients plus vieux, ceux résidants à Gonaïves ainsi que ceux pratiquant le vaudou étaient plus souvent infectés par le VHS-2. Dans notre second article, nous avons démontré que les normes subjectives, le contrôle comportemental perçu et les attitudes étaient des déterminants importants de l’intention d’utilisation du condom. Les clients qui avaient des antécédents d’ITS ou avaient utilisé le condom lors de la dernière relation sexuelle avec la TS étaient aussi plus susceptibles d’avoir l’intention d’en faire usage dans le futur. Les résultats du dernier article ont montré que la prévalence des comportements de violence envers les partenaires intimes était élevée. De plus, la violence émotionnelle et physique était associée à l’utilisation inconstante du condom avec les différentes partenaires sexuelles. En conclusion, cette étude suggère que les clients de TS agiraient comme un pont de transmission facilitant la propagation du VIH/ITS dans la population générale en Haïti et que la violence semblerait également jouer un rôle dans la transmission de ces infections. Nos résultats soulignent le besoin d’interventions en prévention du VIH et des ITS ciblant cette population vulnérable, incluant la problématique de la violence. / Male clients of FSWs are a high risk group for HIV and are considered a “bridge” of transmission between FSWs and women in the general population, through unprotected sex. In spite of their high risk behaviours, clients of FSWs have rarely been studied and they have been the target of few interventions. Therefore, the specific objectives of this thesis were to examine 1) estimate the prevalence of HIV, syphilis and HSV-2 (herpes simplex virus 2) infections and their associated risk factors among clients of FSWs in Haiti, to 2) examine the determinants of intention to condom use, and 3) estimate the prevalence of violence towards their intimate partners and its association with sexual risky behaviours. A cross-sectional survey was conducted among 378 clients visiting commercial sex sites in St-Marc and Gonaives, in Haiti. A structured questionnaire and dried blood spot samples were used to collect the behavioural and biological data. Our first research paper found that HIV/STI prevalence was remarkably high among clients of FSWs. These men had many sex partners and condom use differed, depending on the category of partner. Multivariate analysis indicated that clients who had tried marijuana, were practicing Voodoo, had a history of STI or were infected with HSV-2 were more often HIV-positive. Living in Gonaives, not being Protestant, being employed, and having tried marijuana were associated with syphilis infection. Older clients, residents of Gonaives and Voodoo practitioners were more likely to be infected with HSV-2. The second article revealed that subjective norms, perceived behavioural control and attitudes were predictors of intention to use condoms within this population. Clients having had a previous STI and who used condoms the last time they had sexual intercourse with a FSW were more likely to have the intention to use them in the future. The last article showed that prevalence of lifetime IPV was high among clients of FSWs. Moreover, history of emotional and physical IPV were strong predictors of inconsistent condom use with the different sexual partners. The fact that these abusive men are also more likely to be infected with an STI puts their sexual partners at high risk of infection. In summary, this study suggested that clients of FSWs likely act as a bridge population facilitating the spread of HIV/STI throughout the general population in Haiti and that violence seemed to play a role in the transmission. Our findings highlight the importance of STI/HIV prevention interventions addressing this vulnerable population, including gender-based violence.

Given the lack of effective vaccine or medicine, changing an individual's risk behaviours has been crucial in preventing the spread of HIV. Consistent and correct condom use has been considered as the most effective form of HIV prevention among female sex workers. Despite coordinated national level interventions over the last decade, a consistent decline in condom use among female sex workers has been evidenced in the Ethiopian context, particularly with non-paying partners. Thus far, no study has been produced that has illustrated major determinants of consistent condom use among female sex workers which would help in developing effective intervention strategies for the prevention of HIV spread in the country. In other countries, the Information, Motivation and Behaviour (IMB) model has been used to identify individual level determents of condom use. However, the researcher postulated that behaviour emanating from the personality structure of individuals could be the fundamental individual level determents of adherence to condom use and chose to investigate this using the Enneagram theory of personality, which was acknowledged for its heuristic value in explaining and enhancing self-development of at-risk individuals. This cross-sectional study was conducted in Addis Ababa. With the Without Finite Population Correction of the Sample Size Estimation Formula, the sample size of 350 was set and participants were recruited using Respondent-Driven Sampling (RDS). Using trained female sex workers, the Essential Enneagram Test (EET) and an Information-Motivation-Behaviour (IMB) questionnaire were administered to collect data. General Linear Modeling (GLM) Multivariate analysis was carried out to assess the correlation between personality style and consistent condom use among participants in the last seven days before the interview. The finding of this study revealed that personality type, measured by the Essential Enneagram Test (EET), is able to predict adherence to condom use among female sex workers and provided a new dimension for policy makers and practitioners in behavioural intervention programmes, such as Information-Education-Communication, peer-to-peer approaches, as well as health and rehabilitation services by using the Enneagram principles and universal growth process. / Psychology / D. Litt. et Phil. (Psychology)

In this study semi-structured, in-depth individual interviews were conducted with sixteen female street children aged 15 to 18, who were engaged in commercial sex work. These children were conveniently selected to explore the social dislocation of and social support for female street children engaged in commercial sex work. In addition, two focus group discussions consisting of nine female street children each, as well as seven key informant individual interviews, were conducted. This study found that female children engaged in commercial sex work experienced a high degree of social dislocation and that the children who participated in this study tended to create their own communities and isolated themselves from the broader community in which they lived. This study further found that different support programmes had been introduced to alleviate the problems experienced by these children and that a number of organisations delivered support services to address their needs. / Sociology / M. A. (Sociology)

Les clients de TS sont considérés comme un groupe à risque de VIH et aussi agiraient comme un « pont de transmission » entre les TS et les femmes de la population générale. En dépit de leurs comportements sexuels à risque, les clients de TS ont été rarement étudiés. En conséquence, les objectifs spécifiques de cette thèse étaient : 1) estimer la prévalence du VIH, de la syphilis, du VHS-2 (virus de l’herpès simplex et 2) des facteurs de risque associés chez les clients de TS en Haïti, 2) examiner les déterminants de l’intention d’utilisation du condom, et 3) estimer la prévalence des comportements de violence et ses conséquences. Pour ce faire, une enquête transversale a été effectuée en 2006 auprès de 378 clients fréquentant les milieux de prostitution de St-Marc et de Gonaïves, en Haïti. Un questionnaire structuré ainsi que des échantillons de sang séché sur papier filtre ont été utilisés pour la collecte de données comportementales et biologiques. Notre premier article a montré une prévalence élevée du VIH et des ITS chez les clients. Ces hommes avaient plusieurs partenaires sexuelles avec lesquelles l’utilisation du condom variait. Les clients qui avaient déjà consommé de la marijuana, pratiquaient le vaudou, avaient des antécédents d’ITS ou étaient infectés par le VHS-2, avaient plus de chances d’être positifs au VIH. Le fait d’habiter Gonaïves, de ne pas être protestant, d’être employé et d’avoir déjà essayé la marijuana était associé à l’infection à la syphilis. Tandis que les clients plus vieux, ceux résidants à Gonaïves ainsi que ceux pratiquant le vaudou étaient plus souvent infectés par le VHS-2. Dans notre second article, nous avons démontré que les normes subjectives, le contrôle comportemental perçu et les attitudes étaient des déterminants importants de l’intention d’utilisation du condom. Les clients qui avaient des antécédents d’ITS ou avaient utilisé le condom lors de la dernière relation sexuelle avec la TS étaient aussi plus susceptibles d’avoir l’intention d’en faire usage dans le futur. Les résultats du dernier article ont montré que la prévalence des comportements de violence envers les partenaires intimes était élevée. De plus, la violence émotionnelle et physique était associée à l’utilisation inconstante du condom avec les différentes partenaires sexuelles. En conclusion, cette étude suggère que les clients de TS agiraient comme un pont de transmission facilitant la propagation du VIH/ITS dans la population générale en Haïti et que la violence semblerait également jouer un rôle dans la transmission de ces infections. Nos résultats soulignent le besoin d’interventions en prévention du VIH et des ITS ciblant cette population vulnérable, incluant la problématique de la violence. / Male clients of FSWs are a high risk group for HIV and are considered a “bridge” of transmission between FSWs and women in the general population, through unprotected sex. In spite of their high risk behaviours, clients of FSWs have rarely been studied and they have been the target of few interventions. Therefore, the specific objectives of this thesis were to examine 1) estimate the prevalence of HIV, syphilis and HSV-2 (herpes simplex virus 2) infections and their associated risk factors among clients of FSWs in Haiti, to 2) examine the determinants of intention to condom use, and 3) estimate the prevalence of violence towards their intimate partners and its association with sexual risky behaviours. A cross-sectional survey was conducted among 378 clients visiting commercial sex sites in St-Marc and Gonaives, in Haiti. A structured questionnaire and dried blood spot samples were used to collect the behavioural and biological data. Our first research paper found that HIV/STI prevalence was remarkably high among clients of FSWs. These men had many sex partners and condom use differed, depending on the category of partner. Multivariate analysis indicated that clients who had tried marijuana, were practicing Voodoo, had a history of STI or were infected with HSV-2 were more often HIV-positive. Living in Gonaives, not being Protestant, being employed, and having tried marijuana were associated with syphilis infection. Older clients, residents of Gonaives and Voodoo practitioners were more likely to be infected with HSV-2. The second article revealed that subjective norms, perceived behavioural control and attitudes were predictors of intention to use condoms within this population. Clients having had a previous STI and who used condoms the last time they had sexual intercourse with a FSW were more likely to have the intention to use them in the future. The last article showed that prevalence of lifetime IPV was high among clients of FSWs. Moreover, history of emotional and physical IPV were strong predictors of inconsistent condom use with the different sexual partners. The fact that these abusive men are also more likely to be infected with an STI puts their sexual partners at high risk of infection. In summary, this study suggested that clients of FSWs likely act as a bridge population facilitating the spread of HIV/STI throughout the general population in Haiti and that violence seemed to play a role in the transmission. Our findings highlight the importance of STI/HIV prevention interventions addressing this vulnerable population, including gender-based violence.

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)

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