1.      ABSTRACT

Schistosomiasis remains a major public health problem in developing countries due to its impact on child health, nutrition, cognitive and physical development. Infection is controlled by treatment using the drug of choice Praziquantel (PZQ). In an endemic setting, schistosome infections overlap with other infections/diseases including geohelminths, and malaria. The World Health Organization together with other Global Initiatives advocate for regular deworming of school children to reduce morbidity.  Pre-school children (aged 1-5 years) who have been until recently excluded from schistosome control programmes can now benefit from treatment. Despite this progress, schistosomiasis-endemic countries including Kenya are still slow in embracing this change. To date, the efficacy of praziquantel treatment for schistosomiasis control in preschool children remains unknown.  Furthermore, despite annual mass treatment of school aged children in the endemic sites, disease prevalence in transmission hotpots remains high with levels of malaria and anemia constantly being indifferent. The incidence of falciparum malaria and immune dynamics due to possible modulation of immune responses by schistosomes and its effects on malaria treatment is the emphasis of this study.  Although there have been studies of malaria-schistosome co-infections, they have been biased towards older primary school children (since these were the target for schistosome control), hence little is known about the dynamics of these co-infection’s in the pre-school children. With emerging studies showing schistosome immunomodulation of the host’s phenotype in young children, there is need to understand the global effects of these responses on health in very young children. This study therefore, focuses on 1-5 year old children endemically exposed to schistosomiasis and malaria, asking the question “what is the immunological impact of schistosome coinfection with malaria on incidence of malaria re-infections, and on immune responses and disease treatment in 1-5 year old children?” It uses an elaborate design allowing (1) assessing the general prevalence and intensity of schistosomiasis in this age group, determining treatment efficacy and identifying potential molecular and immune biomarkers of infection, infection intensity and morbidity (2) determining effect of schistosomiasis infection on Plasmodium falciparum specific cytokine and antibody immune responses, (3) evaluating if active chronic infection is associated to clinical incidence of malaria. This study will therefore evaluate the impact of co-infections on immunological correlates of disease and their consequences for treatment and mass drug administration (MDA) programs. It will also provide information that could be used later as key performance indicators of pediatric PZQ efficacy. This will inform governments and policy makers on health system strengthening strategies to cater for the need of this vulnerable population.