The potential impact of including pre-school aged children in the praziquantel mass-drug administration programmes on the S.haematobium infections in Malawi: a modelling study

Background Mass drug administration (MDA) of praziquantel is an intervention used in the treatment and prevention of schistosomiasis. In Malawi, MDA happens annually across high-risk districts and covers around 80% of school aged children and 50% of adults. The current formulation of praziquantel is not approved for use in the preventive chemotherapy for children under 5 years old, known as pre-school aged children (PSAC). However, a new formulation for PSAC will be available by 2022. A comprehensive analysis of the potential additional benefits of including PSAC in the MDA will be critical to guide policy-makers. Methods We developed a new individual-based stochastic transmission model of Schistosoma haematobium for the 6 highest prevalence districts of Malawi. The model was used to evaluate the benefits of including PSAC in the MDA campaigns, with respect to the prevalence of high-intensity infections (> 500 eggs per ml of urine) and reaching the elimination target, meaning the prevalence of high-intensity infections under 5% in all sentinel sites. The impact of different MDA frequencies and coverages is quantified by prevalence of high-intensity infection and number of rounds needed to decrease that prevalence below 1%. Results Including PSAC in the MDA campaigns can reduce the time needed to achieve the elimination target for S. haematobium infections in Malawi by one year. The modelling suggests that in the case of a lower threshold of high-intensity infection, currently set by WHO to 500 eggs per ml of urine, including PSAC in the preventive chemotherapy programmes for 5 years can reduce the number of the high-intensity infection case years for pre-school aged children by up to 9.1 years per 100 children. Conclusions Regularly treating PSAC in the MDA is likely to lead to overall better health of children as well as a decrease in the severe morbidities caused by persistent schistosomiasis infections and bring forward the date of elimination. Moreover, mass administration of praziquantel to PSAC will decrease the prevalence among the SAC, who are at the most risk of infection. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial This was not a clinical trial ### Funding Statement IH, TM and TBH acknowledge funding from the MRC Centre for Global Infectious Disease Analysis (reference MR/R015600/1), jointly funded by the UK Medical Research Council (MRC) and the UK Foreign, Commonwealth & Development Office (FCDO), under the MRC/FCDO Concordat agreement and is also part of the EDCTP2 programme supported by the European Union. TM and TBH were also funded by the Thanzi la Onse grant (RCUK MR/P028004/1). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Not applicable. All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data generated or analysed during this study are included in this published article or the referenced materials. The MDA coverage per year and age group as used in the model is included in the Supplementary Information. * MDA : mass drug administration PSAC : pre-school aged children SAC : school aged children STH : soil-transmitted helminths TLO : Thanzi la Onse WB : worm burden WHO : World Health Organisation