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Soil-transmitted helminth (STH) (A. lumbricoides, T. trichiura and hookworm) infections are a significant public health concern in Honduras. These infections are treatable using inexpensive anthelmintic medications, however long-term control and eradication will require large investments in public and private sanitation infrastructure. Importantly, both types of interventions are targeted towards high-risk populations and regions rather than individuals. The goal of this thesis is to contribute to improving the efficiency of soil-transmitted helminth control efforts in Honduras. In our first study, we use multiple regression analyses to identify determinants of STH infections and generate estimates of A. lumbricoides, T. trichiura and hookworm infection prevalence, as well as recommended deworming frequencies, for each of Honduras’ 298 municipalities. Our estimates suggest that prevalence of all three infections has declined over time, however 75% of municipalities still require annual or semi-annual deworming. In our second study, we quantify how the type of region used for measuring prevalence and allocating resources can impact the success and efficiency of public health programs. More specifically, we compare administrative regions to alternative zoning schemes at the same geographic scale. Our findings suggest that regions designed to be homogeneous with respect to prevalence can be more efficient than existing municipalities (at the same scale) for distributing resources. This research has implications on future control efforts. / Thesis / Master of Science (MSc)

Over the last decade, the incidence rates of many sexually transmitted infections (STI) have been on the rise, especially amongst young adults. Popular Canadian media outlets have speculated that the reason behind these increases is the use of mobile dating applications which foster romantic and sexual connections. This cross-sectional study assesses whether students who use mobile dating apps are more or less likely to have been diagnosed with an STI in the previous 12 months and engage in risky sexual behaviour, compared to students who did not use mobile dating apps in the previous 12 months. An anonymous online questionnaire was used to collect data from 965 study participants currently enrolled at an Ontario university. The survey required participants to self-report STI testing behaviour and diagnoses, as well as sexual behaviours, including number of sexual partners, relationship type, condom use, substance use and sex work. I found that Ontario university students who used dating apps in the previous 12 months were more likely to have a greater number of sexual partners in the previous year (p<0.05), have multiple concurrent sexual partners (OR=10.72, 95% CI: 6.10-18.84), frequently use alcohol (OR=3.94, 95% CI:2.17-7.14) and cannabis (OR=3.36, 95% CI:1.45-7.78) in combination with sexual activity, and were more likely to have been tested for STIs in the previous 12 months (OR=2.25, 95% CI: 1.73-2.94) compared to non-dating app users. However, mobile dating app users were not more likely to have been diagnosed with an STI in the previous 12 months compared to non-dating app users. / Thesis / Master of Public Health (MPH) / This study investigated whether students who use mobile dating apps are more or less likely to engage in risky sexual behavior, and to have been tested for and diagnosed with a sexually transmitted infection (STI) in the previous 12 months, compared to students who do not use mobile dating apps. An anonymous online survey was used to collect data on sexual behaviour and STI history from Ontario university students. I found that Ontario university students who used dating apps in the previous 12 months were more likely to have a greater number of sexual partners in the previous year, have multiple concurrent sexual partners, use alcohol and cannabis in combination with sexual activity, and get tested for STIs more frequently than non-dating app users. However, mobile dating app users were not more likely to have been diagnosed with an STI in the previous 12 months compared to non-dating app users.

Animals are ecological landscapes that host communities of microbes often referred to as microbiomes. These microbes can be transferred between individuals when they come into contact, such as during mating. Microbes that reside in or on any aspect of a host that becomes exposed to the reproductive tract or gametes comprise the reproductive microbiome. These microbes within the reproductive microbiome are important to overall host biology because they can influence host reproductive function, and thus play a role in shaping host ecology, evolution, and fitness. Though previous work has revealed much about the impact of beneficial and pathogenic microbes within the reproductive tract, much is left to be learned from describing the dynamic nature of the reproductive microbiome, and ultimately, how it affects host fitness. For my dissertation, I asked questions regarding how and why reproductive microbiome diversity varies among individuals. For instance, does reproductive microbiome diversity vary with respect to the number of mates or mating activity? Does reproductive microbiome diversity vary with host age or breeding stage? Are there fitness consequences associated with differences in reproductive microbiome diversity? To explore these questions, I studied tree swallows (Tachycineta bicolor), a socially monogamous bird in which both females and males engage in extra-pair mating activity. I focused on the cloacal microbiome as it is the site of contact during mating, and thus where microbes can be sexually transferred between individuals. I found that social partners did not have more similar cloacal microbiome diversity compared to other individuals in the same population, and that cloacal microbiome diversity was similar between sexes (Chapter II). By combining an observational approach with a hormone implant manipulation, I found that neither the number of sires per brood nor the increased mating activity of females significantly influenced cloacal microbiome richness or community structure. However, female age and breeding stage did significantly correlate with cloacal microbiome richness and community structure (Chapter III). Based on these findings, I hypothesized that the effect of mating activity on variation in the cloacal microbiome may only be detectable over a female's lifetime, and not within a single breeding season. In addition, I found evidence for a relationship between lay date and cloacal microbiome structure, after controlling for age. And I found that older females lay earlier in the season compared to younger, first-time breeding females (Chapter IV). These results provide support for a relationship between lay date and the cloacal microbiome and highlight the importance of age to this relationship. Lastly, I discussed future steps that can be taken to extend the framework established by my dissertation research, and thereby gain further insight into the factors shaping the reproductive microbiome (Chapter V). / Doctor of Philosophy / Animals host communities of microbes often referred to as microbiomes, and these microbes can be transferred between individuals when they come into contact, such as during mating. Microbes that reside in or on any part of a host that becomes exposed to the reproductive tract make up the reproductive microbiome. These microbes within the reproductive microbiome are important to an animal's biology because they can influence reproductive function, such as fertilization and pregnancy success. Though previous work has revealed much about the impact of beneficial and pathogenic microbes within the reproductive tract, much is left to be learned from describing the dynamic nature of the reproductive microbiome as a whole and how it affects an animal's reproductive success. For my dissertation, I sought to understand how and why reproductive microbiome diversity varies among individuals, especially in relation to mating. To explore these questions, I studied tree swallows (Tachycineta bicolor), a species of bird in which females and males will pair up to breed and rear young, yet both may mate with individuals other than their partner. I focused on the microbiome within the cloaca of birds as it is where contact is made during mating, and thus where microbes can be sexually transferred between individuals. I found that social partners did not have more similar cloacal microbiome diversity compared to other individuals in the same population, and that cloacal microbiome diversity was similar between females and males (Chapter II). Since tree swallows frequently mate with multiple partners and it is possible for bacteria to be acquired though each mating attempt, I proposed that it is important to consider the number of mates per individual when assessing the diversity of the cloacal microbiome. I then performed observational and experimental studies where I assessed the number of mates per female and manipulated female sexual activity with hormone implants. I found that neither the number of sires per brood nor the increased mating activity of females influenced cloacal microbiome diversity, however, female age and breeding stage were significantly associated with cloacal microbiome diversity (Chapter III). Based on these findings, I hypothesized that the effect of mating activity on variation in the cloacal microbiome may only be detectable over a female's lifetime, and not within a single breeding season. In addition, I found evidence for a relationship between lay date and cloacal microbiome structure, after controlling for age. And I found that older females lay earlier in the season compared to younger, first-time breeding females (Chapter IV). Taken together, these results provide support for a relationship between lay date and the cloacal microbiome and highlight the importance of age to this relationship. Lastly, I discussed future steps that can be taken to extend the framework established by my dissertation research and gain further insight into factors shaping the reproductive microbiome (Chapter V).

Life-history strategies are adaptations in behavior, physiology, and anatomy that influence survival and reproductive success. Variation in life-history strategies is often determined by adaptations to environmental conditions and trade-offs with sexually-selected signals. One of the aspects controlling life-history trade-offs is the endocrine system. Testosterone is a hormone that mediates several key aspects of male reproduction, yet little is known about the causes and consequences of variation in testosterone. Using rufous-collared sparrows (Zonotrichia capensis), a Neotropical songbird with a wide distribution, I explored geographical patterns of variation in testosterone levels and infection by haemosporidians, a type of blood parasite. I found that testosterone did not vary with elevation, nor predict haemosporidian infection, but males in breeding condition were more likely to be infected (Chapter I). High levels of testosterone have been associated with an increased number of sexual contacts and can suppress the immune response, thus it may increase the risk of sexually transmitted infections. By studying the communities of bacteria that reside in the cloaca of birds, I found that they were different depending on testosterone levels, and that high-testosterone males had higher relative abundance of Chlamydiae, a class of intracellular pathogens (Chapter II). During the breeding season there is an increase in physical contacts among individuals, testosterone levels increase in males, and there are additional energetic demands, all of which can increase exposure to bacteria or facilitate infection. I compared the cloacal microbiome of the same individuals between breeding and non-breeding seasons, and found that in males, but not in females, bacterial richness and phylogenetic diversity increased when birds were in reproductive condition. This suggested that the cloacal microbiome in birds is dynamic and responsive to breeding condition and sex of the host (Chapter III). Lastly, I synthesized the most relevant findings and suggested directions for future work (Chapter IV). I conclude that variation in testosterone is not always associated with immune suppression, and that the links among reproductive physiology, behavior, and the microbiome can provide insight into the evolution of life-history strategies. / Ph. D.

This dissertation had three primary aims. The first aim was to systematically review evidence documenting incidence of sexually transmitted infections (STI) during pregnancy. Eighteen papers were included in the final review which reported incidence of five STIs: chlamydia, gonorrhea, human papillomavirus (HPV), herpes simplex virus type 2 (HSV-2) and human immunodeficiency virus (HIV). The review found that there are very limited data on incidence of STIs during pregnancy and even fewer data comparing risk between pregnant and non-pregnant women. Although data are limited, studies suggest that women continue to acquire STIs during pregnancy, with incidence varying by type of infection, population of interest and geographic setting. Highest incidence was found for HPV and chlamydia although some studies of chlamydia showed low proportions of pregnant women infected. Studies in which partners were known to be infected with HSV-2 and HIV showed higher rates of acquisition in pregnant women compared to studies where partner status was not known. The second aim of this dissertation was to describe the impact of pregnancy on behavioral risk factors and vaginal practices that are associated with increased risk of STI acquisition. Data for this and the following aim came from the Methods for Improving Reproductive Health in Africa (MIRA) study, a randomized clinical trial conducted in South Africa and Zimbabwe 2003-2006. The analysis for the second aim included women in the MIRA trial who had a pregnancy during follow-up. Pregnancy was found to decrease sexual activity, particularly in the third trimester, but women were more likely to report sex without condoms while pregnant. There were lower reports by women during pregnancy of other risk factors for STI acquisition, including anal sex, concurrent sexual relationships and new sex partners. Vaginal wiping and insertion of material into the vagina, potentially important mechanisms for STI acquisition, were also less common during pregnancy. The data from this aim present a complicated picture of risk for STIs during pregnancy as a result of increased unprotected sex but decreased frequency of other known behavioral risk factors. The third and final aim of the dissertation was to measure incidence of four STIs in pregnant and non-pregnant women and to evaluate whether women are at greater risk during pregnancy for acquiring four STIs: chlamydia, gonorrhea, trichomoniasis and HIV. This analysis included 4,549 women 18-50 years of age, 17% (N=766) of whom had a pregnancy during follow-up. In general, women continued to be sexually active but reported less overall sex than non-pregnant women. Report of condom use was lower during pregnancy as were other types of high risk sexual behaviors, such as multiple sexual partners, sex in exchange for drugs or money and anal sex, as well vaginal practices. STI incidence was measured during pregnancy and it was found that women continued to acquire STIs when pregnant. In addition, during periods when women became pregnant, they appeared to be a high risk for acquiring chlamydia, trichomoniasis and HIV. Finally, in examining the association between pregnancy status and STI risk, we found that in multivariable models adjusted for demographic and time-varying self-reported behavioral risk factors and vaginal practices, pregnancy was not associated with increased STI risk. However in visit intervals when women became pregnant, they appeared to be at higher risk for contracting chlamydia compared to non-pregnant periods.