Determining the optimal strategies to achieve elimination of transmission for Schistosoma mansoni

Klodeta Kura,T Deirdre Hollingsworth,Diepreye Ayabina,Roy M Anderson

doi:10.1186/s13071-022-05178-x

Abstract

BackgroundIn January 2021, the World Health Organization published the 2021–2030 roadmap for the control of neglected tropical diseases (NTDs). The goal for schistosomiasis is to achieve elimination as a public health problem (EPHP) and elimination of transmission (EOT) in 78 and 25 countries (by 2030), respectively. Mass drug administration (MDA) of praziquantel continues to be the main strategy for control and elimination. However, as there is limited availability of praziquantel, it is important to determine what volume of treatments are required, who should be targeted and how frequently treatment must be administered to eliminate either transmission or morbidity caused by infection in different endemic settings with varied transmission intensities.Methods and ResultsIn this paper, we employ two individual-based stochastic models of schistosomiasis transmission developed independently by the Imperial College London (ICL) and University of Oxford (SCHISTOX) to determine the optimal treatment strategies to achieve EOT. We find that treating school-age children (SAC) only is not sufficient to achieve EOT within a feasible time frame, regardless of the transmission setting and observed age–intensity of infection profile. Both models show that community-wide treatment is necessary to interrupt transmission in all endemic settings with low, medium and high pristine transmission intensities.ConclusionsThe required MDA coverage level to achieve either transmission or morbidity elimination depends on the prevalence prior to the start of treatment and the burden of infection in adults. The higher the worm burden in adults, the higher the coverage levels required for this age category through community-wide treatment programmes. Therefore, it is important that intensity and prevalence data are collected in each age category, particularly from SAC and adults, so that the correct coverage level can be calculated and administered.Graphical

Highlights

In January 2021, the World Health Organization published the 2021–2030 roadmap for the control of neglected tropical diseases (NTDs)
The required Mass drug administration (MDA) coverage level to achieve either transmission or morbidity elimination depends on the prevalence prior to the start of treatment and the burden of infection in adults
Percentage of population having > 0 eggs per gram [epg] Percentage of population having ≥ 400 epg on the baseline prevalence prior to treatment, the precise form of the age–intensity profile of infection and the strategy adopted in terms of MDA coverage and treatment frequency. Building on this past published research, we explore whether we can achieve elimination of transmission (EOT) by considering the following scenarios: 1. Can we move from elimination as a public health problem (EPHP) to EOT? In this scenario, we explore whether we can move towards EOT after achieving EPHP

Summary

Introduction

In January 2021, the World Health Organization published the 2021–2030 roadmap for the control of neglected tropical diseases (NTDs). Mass drug administration (MDA) of praziquantel continues to be the main strategy for control and elimination. As there is limited availability of praziquantel, it is important to determine what volume of treatments are required, who should be targeted and how frequently treatment must be administered to eliminate either transmission or morbidity caused by infection in different endemic settings with varied transmission intensities. Mass drug administration (MDA), using the drug praziquantel (PZQ), is the main form of control at present, alongside behaviour modification and improvement in sanitation. According to the World Health Organization (WHO), an estimated 236 million people require MDA worldwide, of which 90% live in Africa [8]. In 2016 nearly 24,000 people died from schistosomiasis, in reality this number is believed to be higher, as very rarely is schistosomiasis recorded in death certificates

Methods

Results

Discussion

Conclusion