Coordinated Use of Anthelminthic Drugs in Control Interventions: a Manual for Health Professionals and Programme Managers
Treating children infected with intestinal worms is one of the simplest and most cost–effective ways to improve their health.
The recommendations are intended for a wide audience, including policy-makers and their expert advisers as well as technical and programme staff at government institution...s and organizations involved in the design, implementation and expansion of programmes to control soil-transmitted helminth infections.
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Soil-transmitted helminths are a group of intestinal worms that include Ascaris lumbricoides (giant roundworm), Trichuris trichiura (whipworm), and Ancylostoma spp. (A. duodenale, A. ceylanicum) and Necator americanus (hookworms). Despite the clear biological differences among the different species,... their transmission is characterized by the same sequence of events: (i) infected individuals excrete worm eggs through their stool in soil; (ii) under optimal conditions of moisture and temperature the excreted eggs develop into infectious stages; and (iii) finally, infection occurs through oral uptake (Ascaris, Ancylostoma and Trichuris) or skin penetration (Ancylostoma and Necator) of these infectious stages (embryonated eggs and third stage larvae) that reside in the soil and/or in the environment (referring to their common name).
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This video is part of a comprehensive medical school microbiology, immunology & infectious diseases course. Your comments on videos will be key as we iterate content.
Diagnostic performance, cost-effectiveness, ease of performance, rapidity and in-field applicability of tests for Soil-transmitted helminth infections.
Infections by the soil-transmitted helminths (STH), including Ascaris lumbricoides, Trichuris trichiura, Ancylostoma duodenale/Necator americanus (hookworms), and Strongyloides stercoralis, disproportionately affect children around the world. Because of their transmission associated with poor sanita...ry conditions and inadequate hygiene practices, higher burden of disease is seen in children from developing countries from sub-Saharan Africa, Southeast Asia, and Latin America. Approximately 267 million preschool-age children (PSAC) and 568 million school-age children (SAC) worldwide are at risk of STH infection as well as impaired child growth and cognitive development from A. lumbricoides, T. trichiura, and hookworm infections, and death due to severe S. stercoralis infection. Thus, their control is a global health priority.
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Soil-transmitted helminths (STH) affect 1.45 billion people worldwide, and high intensity infections are associated with anemia, undernutrition and impaired cognition, particularly among children. Mathematical models suggest it may be possible to interrupt the transmission of STH in a community by e...xpanding mass drug administration (MDA) from targeted high-risk groups (primarily school-aged children and women of child-bearing age) to all community members with high coverage. The DeWorm3 Project will test the feasibility of this approach to interrupting the transmission of STH using a series of cluster randomized trials in Benin, India and Malawi. Each study area (population 80,000) will be divided into 40 clusters and randomized to community-wide or standard-of-care targeted MDA for three years. Two years following the final round of MDA, prevalence of STH will be compared between arms and transmission interruption assessed in each cluster. The DeWorm3 trials will provide stakeholders with information regarding the potential to switch from STH control to a more ambitious and sustainable strategy.
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Website last accessed on 24.03.2023
Education and information about Soil-Transmitted Helminths including Human Hookworm, Roundworm and Whipworm.
Background: The human helminth infections include ascariasis, trichuriasis, hookworm infections, schistosomiasis, lymphatic filariasis (LF) and onchocerciasis. It is estimated that almost 2 billion people worldwide are infected with helminths. Whilst the WHO treatment guidelines for helminth infecti...ons are mostly aimed at controlling morbidity, there has been a recent shift with some countries moving towards goals of disease elimination through mass drug administration, especially for LF and onchocerciasis. However, as prevalence is driven lower, treating entire populations may no longer be the most efficient or cost-effective strategy. Instead, it may be beneficial to identify individuals or demographic groups who are persistently infected, often termed as being “predisposed” to infection, and target treatment at them.
Methods: The authors searched Embase, MEDLINE, Global Health, and Web of Science for all English language, humanbased papers investigating predisposition to helminth infections published up to October 31st, 2017. The varying definitions used to describe predisposition, and the statistical tests used to determine its presence, are summarised. Evidence for predisposition is presented, stratified by helminth species, and risk factors for predisposition to infection are identified and discussed.
Results: In total, 43 papers were identified, summarising results from 34 different studies in 23 countries. Consistent evidence of predisposition to infection with certain species of human helminth was identified. Children were regularly found to experience greater predisposition to Ascaris lumbricoides, Schistosoma mansoni and S. haematobium than adults. Females were found to be more predisposed to A. lumbricoides infection than were males. Household clustering of infection was identified for A. lumbricoides, T. trichiura and S. japonicum. Ascaris lumbricoides and T. trichiura also showed evidence of familial predisposition. Whilst strong evidence for predisposition to hookworm infection was identified, findings with regards to which groups were affected were considerably more varied than for other helminth species.
Conclusion: This review has found consistent evidence of predisposition to heavy (and light) infection for certain human helminth species. However, further research is needed to identify reasons for the reported differences between demographic groups. Molecular epidemiological methods associated with whole genome sequencing to determine ‘who infects whom’ may shed more light on the factors generating predisposition.
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Website last accessed on 31.03.2023
Youtube Video (Explainity)
Background: Despite several cycles of Mass Drug Administration (MDA), however, the prevalence of Soil-transmitted helminthiasis (STH) remains high in Bangladesh. A clear understanding of local knowledge, attitudes, and practices (KAP) related to the acceptance and utilization of MDA is critical for ...effective implementation of this intervention.
Methods: This research, a cross-sectional descriptive study that utilized quantitative methods, was conducted between February and June 2017. A total of 380 questionnaire surveys were distributed to school-aged children (SAC), the parents of SAC, and school teachers.
Results: Out of 160 SACs, 81.9% knew of STH and 75.6% knew of MDA. SAC showed a high awareness of STH and recognized the importance of preventive measures and MDA. In terms of the parents of SAC and school teachers, close to half of the respondents were knowledgeable about STH and MDA. While nearly all of the participants held positive attitudes toward MDA, the respondents pointed out that school-based MDA presents severe limitations, as non-school-going children are neglected by this effort. A total of 68.3% of all school teachers and 56.8% of all parents of SAC found MDA efforts to be effective.
Conclusion: STH infections still remain a significant public health burden in Bangladesh. Reforming the MDA policy is necessary to achieve the target of STH elimination.
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Soil transmitted helminth (STH) infections are among the most common human infections worldwide with over 1 billion people affected. Many estimates of STH infection are often based on school-aged children (SAC). This study produced predictive risk-maps of STH on a more finite scale, estimated the nu...mber of people infected, and the amount of drug required for preventive chemotherapy (PC) in Ogun state, Nigeria. Georeferenced STH infection data obtained from a cross-sectional survey at 33 locations between July 2016 and November 2018, together with remotely-sensed environmental and socio-economic data were analyzed using Bayesian geostatistical modelling. Stepwise variable selection procedure was employed to select a parsimonious set of predictors to predict risk and spatial distribution of STH infections. The number of persons (pre-school ages children, SAC and adults) infected with STH were estimated, with the amount of tablets needed for preventive chemotherapy. An overall prevalence of 17.2% (95% CI 14.9, 19.5) was recorded for any STH infection. Ascaris lumbricoides infections was the most predominant, with an overall prevalence of 13.6% (95% CI 11.5, 15.7), while Hookworm and Trichuris trichiura had overall prevalence of 4.6% (95% CI 3.3, 5.9) and 1.7% (95% CI 0.9, 2.4), respectively. The model-based prevalence predictions ranged from 5.0 to 23.8% for Ascaris lumbricoides, from 2.0 to 14.5% for hookworms, and from 0.1 to 5.7% for Trichuris trichiura across the implementation units. The predictive maps revealed a spatial pattern of high risk in the central, western and on the border of Republic of Benin. The model identified soil pH, soil moisture and elevation as the main predictors of infection for A. lumbricoides, Hookworms and T. trichiura respectively. About 50% (10/20) of the implementation units require biannual rounds of mass drug administration. Approximately, a total of 1.1 million persons were infected and require 7.8 million doses. However, a sub-total of 375,374 SAC were estimated to be infected, requiring 2.7 million doses. Our predictive risk maps and estimated PC needs provide useful information for the elimination of STH, either for resource acquisition or identifying priority areas for delivery of interventions in Ogun State, Nigeria.
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oil-transmitted helminth (STH) infections are among the most common infections worldwide and affect the poorest and most deprived communities.
They are transmitted by eggs present in human faeces which in turn contaminate soil in areas where sanitation is poor.
The main species that infect peopl...e are the roundworm (Ascaris lumbricoides), the whipworm (Trichuris trichiura) and the hookworms (Necator americanus and Ancylostoma duodenale).
Intestinal worms produce a wide range of symptoms including intestinal manifestations (diarrhoea, abdominal pain), general malaise and weakness. Hookworms cause chronic intestinal blood loss that result in anaemia.
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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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Soil-transmitted helminth (STH) infections are among the most common infections worldwide with an estimated 1.5 billion infected people or 24% of the world’s population. These infections affect the poorest and most deprived communities with poor access to clean water, sanitation and hygiene in tro...pical and subtropical areas, with the highest prevalence reported from sub-Saharan Africa, China, South America and Asia. They are transmitted by eggs present in human faeces, which in turn contaminate soil in areas where sanitation is poor. Over 260 million preschool-age children, 654 million school-age children,108 million adolescent girls and 138.8 million pregnant and lactating women live in areas where these parasites are intensively transmitted, and are in need of treatment and preventive interventions.
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Soil-transmitted helminth (STH) infections are among the most common infections worldwide and affect the poorest and most deprived communities. They are transmitted by eggs present in human faeces which in turn contaminate soil in areas where sanitation is poor.
Accessed on 22.04.2023
To target helminth elimination, a new consortium of research institutes, universities, not-for-profit organizations, and pharmaceutical companies have joined forces and expertise to establish a research and development pipeline for the development of anthelminthics targeti...ng nematodes. The focus is on STH as well as onchocerciasis.
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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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