An estimated 6 million individuals are co-infected with HIV and schistosomiasis. This thesis seeks to add to the comprehension of the epidemiology of HIV and schistosome co-infections in Tanzania,... Show moreAn estimated 6 million individuals are co-infected with HIV and schistosomiasis. This thesis seeks to add to the comprehension of the epidemiology of HIV and schistosome co-infections in Tanzania, by Lake Victoria. It first evaluates Tanzania’s progress regarding HIV care and defines the study population and the challenges it faces in the fight against co-infections. It then explores the impact of Schistosoma infection on HIV outcomes and transmission. One of the main findings is that people who were infected with Schistosoma when they also acquired HIV infection, on average survive longer and have slower decline in CD4 counts than those who were not infected with Schistosoma in the first place. This thesis also shows that individuals with HIV and Schistosoma spp. co-infections have lower viral loads than those with HIV alone, when accounting for time infected with HIV, and estimates the first hazard rate of HIV transmission from co-infected partners. Finally, this thesis explores the impact of HIV infection on the detection of Schistosoma in co-infected people and concludes that co-infected individuals and women are less likely to excrete parasite eggs. Both local and systemic interactions are discussed in light of those results. Show less
In Africa, polyparasitism is the rule rather than the exception. The aim of this thesis was to get a detailed insight into the micro-geographical distribution and patterns of S. mansoni and S.... Show moreIn Africa, polyparasitism is the rule rather than the exception. The aim of this thesis was to get a detailed insight into the micro-geographical distribution and patterns of S. mansoni and S. haematobium co-infections, and how this affects host morbidity. A community-wide study was carried out in a co-endemic focus in the north of Senegal, combining epidemiological, ecological, immunological, and geographical analyses. This multidisciplinary approach led to several new insights. Spatial analyses showed significant clustering of Schistosoma infection and morbidity even on a micro scale; S. mansoni and S. haematobium hotspots were found in different sections of one community. Another major finding was that the presence of S. mansoni in co-infections might protect against S. haematobium-specific urinary tract morbidity. Furthermore, it was observed that S. haematobium antigens induced stronger cytokine responses than those of S. mansoni, indicating that the first species may be more immunogenic. The results of this thesis provide new leads for further research on disease etiology and underlying mechanisms in Schistosoma co-infections. Such knowledge is key to rationalizing and optimizing current schistosomiasis control strategies in co-endemic areas and to developing successful elimination strategies in the future. Show less
