This document provides up-to-date guidance on laboratory studies as well as smallscale (semi-field) and large-scale field trials to assess the efficacy and determine field
application rates of new molluscicide products for control of schistosomiasis.
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Disease: Infection is widespread in poor communities, 221 million people affected worldwide...
Affected Populations: Women, Children...
Prevention and Control: WHO recommends praziquantel for treatment of all forms of schistosomiasis...
Lesson on schistosomiasis (bilharziasis): Causes, Symptoms and Treatment. Schistosomiasis is caused by parasitic blood flukes from the genus schistosoma. Schistosoma cercariae penetrate human skin and enter the bloodstream of the infected individual, where the parasites enter the portal vein. Schist...osoma parasites also enter the mesenteric and bladder circulations, where they release eggs. Symptoms of schistosomiasis are related to the location of the parasites, the parasite burden and the amount of eggs produced. Systems affected in schistosomiasis include the hepatic, splenic, genitourinary, pulmonary, and nervous systems.
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Species of the genus Schistosoma are digenetic trematodes and the causative agents of the Neglected Tropical Disease (NTD) schistosomiasis; a parasitic disease that ranks second only to malaria in terms of socioeconomic impacts. Over 220 million people worldwide are currently infected, 90% of whom l...ive in sub-Saharan Africa (SSA), with an estimated annual mortality of at least 200,000. Infection in humans, as well as alternative mammalian definitive hosts, occurs in contaminated freshwater environments via cercariae shed from specific snail intermediate hosts. Early acute morbidity can occur following cutaneous penetration, sometimes leading to an urticarial rash known as swimmers itch or cercarial dermatitis.
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Schistosomiasis, also known as Bilharzia, is an infection caused by a parasitic worm that lives in fresh water in subtropical and tropical regions. Schistosomiasis is second only to malaria as the most devastating parasitic disease. The parasites that cause schistosomiasis live in certain types of f...reshwater snails. The infectious form, known as cercariae, emerge from the snail and then contaminate the water. People become infected when their skin comes into contact with the contaminated freshwater. Most human infections are caused by Schistosoma mansoni, Schistosoma haematobium, or Schistosoma japonicum.
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Schistosomiasis, also known as bilharzia, is an infection caused by a parasitic worm that lives in fresh water in subtropical and tropical regions.
Schistosomiasis is a chronic parasitic infection caused by worms. It is most common in rural and impoverished populations. In the Americas, the parasite species is Schistosoma mansoni, which is associated with intestinal schistosomiasis. The main risk factor for infection is exposure through househo...ld, work, or recreational activities in fresh water contaminated with faeces from infected humans.
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Schistosomiasis is an acute and chronic parasitic disease caused by blood flukes (trematode worms) of the genus Schistosoma. Estimates show that at least 251.4 million people required preventive treatment in 2021. Preventive treatment, which should be repeated over a number of years, will reduce and... prevent morbidity. Schistosomiasis transmission has been reported from 78 countries. However, preventive chemotherapy for schistosomiasis, where people and communities are targeted for large-scale treatment, is only required in 51 endemic countries with moderate-to-high transmission.
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Human schistosomiasis, a parasitic and often chronic illness, is one of the major neglected tropical diseases worldwide. It is estimated that 240 million people suffer from schistosomiasis, with more than 200000 fatalities recorded each year. Schistosomiasis is caused by an infection of the blood fl...uke Schistosoma and is transmitted to humans through direct contact with infected water.
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With some 134,073,166 people living in endemic communities at risk of infection, Nigeria is the most endemic country in Africa and requires preventive chemotherapy (PC) for a total of 26.3 million persons. The National Schistosomiasis Elimination Programme (NSCHEP), with the support of international... partners, has been implementing PC in Nigeria since 2009 and most recently will need to revise its current strategy (Additional file 1). For example, the new World Health Organization (WHO) guideline has six key recommendations that will dramatically change the implementation of schistosomiasis elimination in endemic countries [3]. However, its impact and programmatic implications will vary from country to country, hence the need for a country-specific analysis. This article discusses these recommendations with specific reference to the challenges and opportunities in Nigeria. We summarise the key pointers in Additional file 1: Box 1 against the six recommendations of the WHO 2022 guideline.
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The control of schistosomiasis was a high priority in China soon after the founding of the People’s Republic of China in 1949, and schistosomiasis japonica was largely brought under control through 7 decades of effort. However, great challenges still exist to completely eliminate schistosomiasis f...rom the country by 2030 due to climate change, natural disasters, socioeconomic development, environmental protection, etc. The progress of the national schistosomiasis control program and the experience
accumulated over past several decades in China is reviewed in this article, and solutions to achieve the elimination of schistosomiasis through a One Health
approach are explored, which addresses complex health issues from a holistic perspective of human-animal-environment interaction.
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Goal and objectives of the guideline
The goal of this guideline is to provide evidence-based recommendations to countries in their efforts to accomplish schistosomiasis morbidity control and elimination as a public health problem, and to move towards interruption of transmission.
The recommendatio...ns contained herein will help countries to implement national schistosomiasis control and elimination programmes and support efforts to verify the interruption of transmission.
The specific objectives are to provide guidance on:
prevalence thresholds, target age groups and frequency of preventive chemotherapy for schistosomiasis;
establishment of water, sanitation and hygiene (WASH) and snail control activities to support control and elimination of schistosomiasis;
use of diagnostic tests in humans in low transmission areas and for moving to, and evaluating the interruption of transmission of schistosomiasis;
tools for the assessment of Schistosoma spp. infection in snail hosts; and
diagnostic tests for the assessment of schistosomiasis infection in animal reservoirs of infection
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Schistosomiasis is widely recognized as a disease that is socially determined. An
understanding of the social and behavioural factors linked to disease transmission and
control should play a vital role in designing policies and strategies for schistosomiasis
prevention and control. To this must b...e added the awareness that schistosomiasis is
also a disease of poverty. It still survives in poverty-stricken, remote areas where there
is little or no safe water or sanitation, and health care is scarce or non-existent. For
a variety of complex reasons, many of which are addressed in this book, the disease
is particularly prevalent in sub-Saharan Africa, and persists in certain areas of rural
China. This concern for human behaviour in an environment of poverty echoes the
concerns of the new research priority for “diseases of poverty” identified by the
Special Programme for Research & Training in Tropical Diseases.
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Schistosomiasis is a chronic disease linked to poverty and is widely endemic, particularly in sub-Saharan Africa. For decades, the World Health Organization has called for a larger role of the primary health care system in schistosomiasis control, and its integration within the routine activities of... primary health care facilities. Here, we reviewed existing studies on the integration of schistosomiasis control measures within the primary health care system, more precisely at the health centre, and we analysed their outcomes.
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In 2014, an estimated 40 million women of reproductive age were infected with Schistosoma haematobium, S. japonicum and/or S. mansoni. In both 2003 and 2006, the World Health Organization (WHO) recommended that all schistosome-infected pregnant and breastfeeding women be offered treatment, with praz...iquantel, either individually or during treatment campaigns. In 2006, WHO also stated the need for randomized controlled trials to assess the safety and efficacy of such treatment. Some countries have yet to follow the recommendation on treatment and many programme managers and pregnant women in other countries remain reluctant to follow the recommended approach.
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The control and elimination of schistosomiasis have over the last two decades involved several strategies, with the current strategy by the World Health Organization (WHO) focusing mainly on treatment with praziquantel during mass drug administration (MDA). However, the disease context is complex wi...th an interplay of social, economic, political, and cultural factors that may affect achieving the goals of the Neglected Tropical Disease (NTD) 2021-2030 Roadmap. There is a need to revisit the current top-down and reactive approach to schistosomiasis control among sub-Saharan African countries and advocate for a dynamic and diversified approach.
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The Community Dialogue Approach is a promising social and behaviour change intervention, which has shown potential for improving health seeking behaviour. To test if this approach can strengthen prevention and control of schistosomiasis at community level, Malaria Consortium implemented a Community ...Dialogue intervention in four districts of Nampula province, Mozambique, between August 2014 and September 2015.
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Despite pandemic-related disruptions, a total of 76.9 million people received treatment for schistosomiasis in 2020, representing a global coverage of 31.9%, compared with 105 million treated in 2019 (coverage of 44.8%).
The latest data published by the World Health Organization (WHO) show that 2...8.6 million fewer people were treated for schistosomiasis (bilharzia) in 2020 than in 2019. This 27% drop in the number of treatments delivered is largely due to the implementation of COVID-19 measures, including school closures.
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Schistosomiasis and soil-transmitted helminths (STH) infections are major public health problems. We aimed to study the 6-mo impact of mass drug administration with praziquantel and albendazole on urinary schistosomiasis and STH.We examined children (aged 2–15 y) from one hamlet, who provided urin...e and faeces samples at baseline (n=197), 1 mo (n=102) and 6 mo (n=92); 67 completed the protocol.At baseline, 47/67 (70.1%) children presented Schistosoma haematobium (75.8% in the baseline total sample) and 12/67 (17.9%) with STH (30.5% in the initial sample, p=0.010). Among the children, 47.3% had heavy Schistosoma haematobium infection. The most frequent STH was Trichuris trichiura in 9.0%. We also found Hymenolepis nana (13.2%) and Plasmodium falciparum (9.1%) infections and anaemia (82.1%). One mo after chemotherapy there was a significant (p=0.013) reduction of Schistosoma haematobium prevalence (23.5%) and a high egg reduction rate (86.9%). Considering the sample of 67 children, the mean egg concentration was 498 at baseline, 65 at 1 mo and 252 at 6 mo (p<0.05). We also observed a reduction in STH infections, 50% in Ascaris lumbricoides, 33.3% in T. trichiura and 50% in hookworms. At 6 mo, the prevalence of Schistosoma haematobium (76.1%) was similar to the baseline and the STH reduction was not significant.Longitudinal studies have reported many losses in these settings, but we were able to show that mass drug administration for control of schistosomiasis and STH present low effectiveness, that reinfections occur rapidly and that stand alone anthelmintic therapy is not a sustainable choice.
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Human schistosomiasis is caused mainly by 3 schistosome species: Schistosoma haematobium, S. mansoni and S. japonicum. S. guineensis, S. intercalatum and S. mekongi have a highly localized distribution in Central Africa and along the Mekong River in South-East Asia, respectively. Soil-transmitted h...elminthiases (STH) are infections caused by 4 parasite species: Ascaris lumbricoides, Trichuris trichiura, Ancylostoma duodenale and Necator americanus. The 2 latter species are indistinguishable microscopically and are usually reported together as “hookworms”. Schistosomiasis and STH are neglected tropical diseases (NTDs) and are transmitted mainly in areas with poor access to clean water and sanitation. The presence of an intermediate snail host in water is essential to allow Schistosoma to complete their life cycle. Schistosomiasis and STH can cause significant morbidity, including anaemia, nutritional disturbances and, in the case of schistosomiasis, granuloma, organ pathology and cancer, and an increased risk of acquisition of HIV. In women, urogenital schistosomiasis may cause vaginal bleeding, pain during sexual intercourse and nodules in the vulva, now described as female genital schistosomiasis. Groups at risk for STH and schistosomiasis are those in need of micronutrients: preschool-aged children (pre-SAC, 1–4 years of age), school-aged children (SAC, 5–14 years), women of reproductive age (WRA) and, in addition for schistosomiasis adult and entire communities in high-risk areas.
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