Schistosomiasis is a debilitating chronic parasitic disease that occurs in the poorest regions of the world, predominantly in sub-Saharan Africa (SSA), infecting around 240 million individuals. With the vision of “a world free of schistosomiasis”, the WHO and its partners have pledged to meet the ambitious goals of controlling morbidity (i.e. as currently defined, to decrease the prevalence of heavy infection intensity to less than 5% across all sentinel sites) of schistosomiasis by 2020 (in all endemic countries), achieving elimination as a public health problem (EPHP) (i.e. as currently defined, to reduce the prevalence of heavy infection intensity to less than 1% in all sentinel sites; in all endemic countries) and the interruption of transmission in selected regions by 2025. However, the guidelines that programmes follow are based predominantly on expert opinion, with limited empirical evidence. It is thus critical that we have the right tools and empirical evidence to help inform, validate or revise the WHO guidelines and help programmes achieve these ambitious goals. This work aims to do this through the following ways:
1. Generation of data: data collected from 7,500 individuals annually, from across ten different geographical sites in Uganda, varying by endemicity level and treatment history of site;
2. Understanding historical global trends towards the WHO goals: collation and analysis of national-level programmatic data from nine countries to determine if the goals have already been reached by some countries and whether the one-size-fits-all approach is useful.
3. Investigating the impact of treatment programmes: since school-aged-children (SAC) are targeted under the WHO guidelines, it is important to understand what impact this has on the wider community if we are to reach the targets.
4. Development of a quantitative tool to aid programmes: this model is aimed to be used as an addition to the monitoring and evaluation tool kits which monitor and project the reduction in prevalence (by intensity group) and can also be used as an advocacy tool.
The study begins with a coarser grain focus at country level and moves to a more detailed, finer grain study at individual host level. Results showed that the control targets were feasible and much earlier than proposed by the guidelines and that EPHP was only feasible in low endemic areas and the finer scale data highlighted the importance of spatial scales on outputs as well as heavily infected individuals present in non-treated pre-SAC and adults. Since at each level, factors have been identified that impact the epidemiology, control and feasibility of elimination, this work highlights and synthesizes possible emergent properties that cannot be understood by the study of the micro- or macro-epidemiology in isolation. This thesis presents all the different elements together to help elucidate the best approach for national control programmes to reach their goals.