Building a global schistosomiasis alliance:an opportunity to join forces to fight inequality and rural poverty

Schistosomiasis,one of the 17 neglected tropical diseases listed by the World Health Organization,presents a substantial public health and economic burden.Of the 261 million people requiring preventive chemotherapy for schistosomiasis in 2013,92%of them lived in sub-Saharan Africa and only 12.7%received preventive chemotherapy.Moreover,in 2010,the WHO reported that schistosomiasis mortality could be as high as 280000 per year in Africa alone.In May 2012 delegates to the sixty-fifth World Health Assembly adopted resolution WHA65.21 that called for the elimination of schistosomiasis,and foresees the regular treatment of at least 75%of school age children in at-risk areas.The resolution urged member states to intensify schistosomiasis control programmes and to initiate elimination campaigns where possible.Despite this,in June 2015,schistosomiasis was indicated to have the lowest level of preventive chemotherapy implementation in the spectrum of neglected tropical diseases.It was also highlighted as the disease most lacking in progress.This is perhaps unsurprising,given that it was also the only NTD with access to drug donations but without a coalition of stakeholders that collaborates to boost commitment and implementation.As a consequence,and to ensure that the WHO NTDs Roadmap Targets of 2012 and World Health Assembly Resolution WHA65.21 are met,the Global Schistosomiasis Alliance(GSA)has been set up.Diverse and representative,the GSA aims to be a partnership of endemic countries,academic and research institutions,international development agencies and foundations,international organizations,non-governmental development organizations,private sector companies and advocacy and resource mobilisation partners.Ultimately,the GSA calls for a partnership to work for the benefit of endemic countries by addressing health inequity and rural poverty.

Elimination of schistosomiasis:the tools required

Background:Historically,the target in the schistosomiasis control has shifted from infection to morbidity,then back to infection,but now as a public health problem,before moving on to transmission control.Currently,all endemic countries are encouraged to increase control efforts and move towards elimination as required by the World Health Organization(WHO)roadmap for the global control of the neglected tropical diseases(NTDs)and the WHA65.21 resolution issued by the World Health Assembly.However,schistosomiasis prevalence is still alarmingly high and the global number of disability-adjusted life years(DALYs)due to this infection has in fact increased due to inclusion of some‘subtle’clinical symptoms not previously counted.Main body:There is a need to restart and improve efforts to reach the elimination goal.To that end,the first conference of the Global Schistosomiasis Alliance(GSA)Research Working Group was held in mid-June 2016 in Shanghai,People’s Republic of China.It reviewed current progress in schistosomiasis control and elimination,identified pressing operational research gaps that need to be addressed and discussed new tools and strategies required to make elimination a reality.The articles emanating from the lectures and discussions during this meeting,together with some additional invited papers,have been collected as a special issue of the‘Infectious Diseases of Poverty’entitled‘Schistosomiasis Research:Providing the Tools Needed for Elimination’,consisting of 26 papers in all.This paper refers to these papers and discusses critical questions arising at the conference related to elimination of schistosomiasis.Conclusion:The currently most burning questions are the following:Can schistosomiasis be eliminated?Does it require better,more highly sensitive diagnostics?What is the role of preventive chemotherapy at the elimination stage?Is praziquantel sufficient or do we need new drugs?Contemplating these questions,it is felt that the heterogeneity of the endemic areas in the world requires WHO policies to be upgraded instituting new,differentiated guidelines.

Developing a comprehensive response for treatment of children under 6 years of age with schistosomiasis:research and development of a pediatric formulation of praziquantel

Schistosomiasis is a parasitic disease caused by blood flukes.The disease is caused by an inflammatory reaction to parasite eggs retained in the liver,bladder and reproductive organs.According to 2017 World Health Organization(WHO)estimates 220 million people are potentially infected,from which probably 10%are children under 6 years of age.The regular treatment approach of a single,oral dose of 40 mg/kg body weight with praziquantel however,is difficult for children under the age of 6,leaving them without a treatment option.In order to address this important gap in treatment target populations,an international public-private partnership that works on a not-for-profit basis in the field of drug research and development for schistosomiasis was established in 2012.This is called the Pediatric Praziquantel Consortium.Its mission was and continues to be to develop,register and provide access to a suitable pediatric praziquantel formulation for treating schistosomiasis in preschool-age children(3-6 months up to 6 years).The Target Product Profile for the pediatric formulation of praziquantel that would be suitable to treat children as young as 3-6 months was then defined by a group of experts,including members from the Pediatric Praziquantel Consortium partner organizations as well as experts from WHO(as observer)and schistosomiasis endemic countries.The development of the drug is ongoing and the Pediatric Praziquantel Consortium aims to submit the regulatory dossier for marketing approval in endemic countries and WHO prequalification in 2018/19 with approval and product launch for schistosomiasis pediatric case management in key endemic countries in 2019.Ultimately,the goal is for the product to be considered for a large-scale mass distribution program by 2022.

Accelerating snail vector genomics

The three most important genera of snails for the transmission of schistosomes are Bulinus,Biomphalaria and Oncomelania.Each of these genera,found in two distantly related families,includes species that act as the intermediate host for one of the three most widespread schistosome species infecting humans,Schistosoma haematobium,S.mansoni and S.japonicum,respectively.An important step in the fight against schistosomiasis in Asia has been taken with the publication of the article"Chromosome-level genome assembly of Oncomelania hupensis:the intermediate snail host of Schistosoma japonicum",which means that genomes for all three major genera,including species across three continents,are now available in the public domain.This includes the first genomes of African snail vectors,namely Biomphalaria sudanica,Bi.pfeifferi and Bulinus truncatus,as well as high-quality chromosome level assemblies for South American Bi.glabrata.Most importantly,the wealth of new genomic and transcriptomic data is helping to establish the specific molecular mechanisms that underly compatibility between snails and their schistosomes,which although diverse and complex,may help to identify potential targets dictating host parasite interactions that can be utilised in future transmission control strategies.This new work on Oncomelania hupensis and indeed studies on other snail vectors,which provide deep insights into the genome,will stimulate research that may well lead to new and much needed control interventions.