Summary Background Food-borne trematodiases are a group of neglected tropical diseases caused by liver, lung, and intestinal parasitic fluke infections. As part of the Global Burden of Diseases, ...Injuries, and Risk Factors Study (GBD 2010 study) and a WHO initiative, we assessed the global burden of human food-borne trematodiasis, as expressed in disability-adjusted life years (DALYs) for the year 2005. Methods We systematically searched electronic databases for reports about human food-borne trematodiasis without language restriction, between Jan 1, 1980, and Dec 31, 2008. We used a broad search strategy with a combination of search terms and parasite and disease names. The initial search results were then screened on the basis of title, abstract, and, finally, full text. Relevant quantitative and qualitative data on human prevalence, morbidity, and mortality of food-borne trematodiasis were extracted. On the basis of available information on pathological and clinical appearance, we developed simplified disease models and did meta-analyses on the proportions and odds ratios of specified sequelae and estimated the global burden of human food-borne trematodiasis. Findings We screened 33 921 articles and identified 181 eligible studies containing quantitative information for inclusion in the meta-analyses. About 56·2 million people were infected with food-borne trematodes in 2005: 7·9 million had severe sequelae and 7158 died, most from cholangiocarcinoma and cerebral infection. Taken together, we estimate that the global burden of food-borne trematodiasis was 665 352 DALYs (lower estimate 479 496 DALYs; upper estimate 859 051 DALYs). Furthermore, knowledge gaps in crucial epidemiological disease parameters and methodological features for estimating the global burden of parasitic diseases that are characterised by highly focal spatial occurrence and scarce and patchy information were highlighted. Interpretation Despite making conservative estimates, we found that food-borne trematodiases are an important cluster of neglected diseases. Funding Swiss National Science Foundation; Institute for Health Metrics and Evaluation.
Summary On Aug 21, 1875, James McConnell published in The Lancet his findings from a post-mortem examination of a 20-year-old Chinese man—undertaken at the Medical College Hospital in Calcutta, ...India—in whom he found Clonorchis sinensis in the bile ducts. Now, exactly 140 years later, we have a sound understanding of the lifecycle of this liver fluke, including key clinical, diagnostic, and epidemiological features. Developments in the so-called -omics sciences have not only advanced our knowledge of the biology and pathology of the parasite, but also led to the discovery of new diagnostic, drug, and vaccine targets. C sinensis infection is primarily related to liver and biliary disorders, especially cholangiocarcinoma. Clonorchiasis mainly occurs in east Asia, as a result of the region's social-ecological systems and deeply rooted cultural habit of consuming raw freshwater fish. The Kato-Katz technique, applied on fresh stool samples, is the most widely used diagnostic approach. Praziquantel is the treatment of choice and has been considered for preventive chemotherapy. Tribendimidine showed good safety and therapeutic profiles in phase 2 trials and warrants further investigation. Still today, the precise distribution, the exact number of infected people, subtle morbidities and pathogenesis, and the global burden of clonorchiasis are unknown. Integrated control strategies, consisting of preventive chemotherapy; information, education, and communication; environmental management; and capacity building through intersectoral collaboration should be advocated.
An estimated 779 million people are at risk of schistosomiasis, of whom 106 million (13·6%) live in irrigation schemes or in close proximity to large dam reservoirs. We identified 58 studies that ...examined the relation between water resources development projects and schistosomiasis, primarily in African settings. We present a systematic literature review and meta-analysis with the following objectives: (1) to update at-risk populations of schistosomiasis and number of people infected in endemic countries, and (2) to quantify the risk of water resources development and management on schistosomiasis. Using 35 datasets from 24 African studies, our meta-analysis showed pooled random risk ratios of 2·4 and 2·6 for urinary and intestinal schistosomiasis, respectively, among people living adjacent to dam reservoirs. The risk ratio estimate for studies evaluating the effect of irrigation on urinary schistosomiasis was in the range 0·02–7·3 (summary estimate 1·1) and that on intestinal schistosomiasis in the range 0·49–23·0 (summary estimate 4·7). Geographic stratification showed important spatial differences, idiosyncratic to the type of water resources development. We conclude that the development and management of water resources is an important risk factor for schistosomiasis, and hence strategies to mitigate negative effects should become integral parts in the planning, implementation, and operation of future water projects.
Summary In 2001, the World Health Assembly (WHA) passed the landmark WHA 54.19 resolution for global scale-up of mass administration of anthelmintic drugs for morbidity control of schistosomiasis and ...soil-transmitted helminthiasis, which affect more than 1·5 billion of the world's poorest people. Since then, more than a decade of research and experience has yielded crucial knowledge on the control and elimination of these helminthiases. However, the global strategy has remained largely unchanged since the original 2001 WHA resolution and associated WHO guidelines on preventive chemotherapy. In this Personal View, we highlight recent advances that, taken together, support a call to revise the global strategy and guidelines for preventive chemotherapy and complementary interventions against schistosomiasis and soil-transmitted helminthiasis. These advances include the development of guidance that is specific to goals of morbidity control and elimination of transmission. We quantify the result of forgoing this opportunity by computing the yearly disease burden, mortality, and lost economic productivity associated with maintaining the status quo. Without change, we estimate that the population of sub-Saharan Africa will probably lose 2·3 million disability-adjusted life-years and US$3·5 billion of economic productivity every year, which is comparable to recent acute epidemics, including the 2014 Ebola and 2015 Zika epidemics. We propose that the time is now to strengthen the global strategy to address the substantial disease burden of schistosomiasis and soil-transmitted helminthiasis.
PURPOSE OF REVIEWPraziquantel (PZQ) is the only drug being used to treat human schistosomiasis on a large scale. This review focuses on current knowledge about the mechanisms of action of PZQ, ...prospects for PZQ resistance, possible future alternative drugs and on exhortations that control of schistosomiasis and other so-called neglected tropical diseases becomes more integrated.
RECENT FINDINGSSchistosome calcium ion (Ca) channels are the only moiety so far identified as the molecular target of PZQ, but the evidence remains indirect. In the presence of cytochalasin D worms survive high concentrations of PZQ and experiments with cytochalasin D also indicated that PZQ induced worm death and Ca influx are not correlated. Despite PZQ being widely used, there is no clinically relevant evidence for resistance to date, but worryingly low-cure rates have been recorded in some studies in Africa. Artemisinins and the related 1,2,4-trioxolanes are new promising antischistosomal compounds, as are inhibitors of a schistosome-specific bifunctional enzyme, thioredoxin-glutathione reductase.
SUMMARYUse of PZQ will increase in the foreseeable future, whether given alone or coadministered with other anthelminthics in integrated control programmes. PZQ resistance remains a threat and its prevention requires adequate monitoring of current mass drug administration programmes and development of new schistosomicides.
To identify areas at highest risk of infectious disease transmission in Africa, we develop a physical distancing index (PDI) based on the share of households without access to private toilets, water, ...space, transportation, and communication technology and weight it with population density. Our results highlight that in addition to improving health systems, countries across Africa, especially in the western part of Africa, need to address the lack of essential domestic infrastructure. Missing infrastructure prevents societies from limiting the spread of communicable diseases by undermining the effectiveness of governmental regulations on physical distancing. We also provide high-resolution risk maps that show which regions are most limited in protecting themselves. We find considerable spatial heterogeneity of the PDI within countries and show that it is highly correlated with detected COVID-19 cases. Governments could pay specific attention to these areas to target limited resources more precisely to prevent disease transmission.
Summary Background Pathogenic intestinal protozoa infections are responsible for substantial mortality and morbidity, particularly in settings where people lack improved sanitation and safe drinking ...water. We assessed the relation between access to, and use of, sanitation facilities and water treatment and infection with intestinal protozoa. Methods We did a systematic review and searched PubMed, ISI Web of Science, and Embase from inception to June 30, 2014, without restrictions on language. All publications were examined by two independent reviewers and were included if they presented data at the individual level about access or use of sanitation facilities or water treatment, in combination with individual-level data on human intestinal protozoa infections. Meta-analyses using random effects models were used to calculate overall estimates. Findings 54 studies were included and odds ratios (ORs) extracted or calculated from 2 × 2 contingency tables. The availability or use of sanitation facilities was associated with significantly lower odds of infection with Entamoeba histolytica or Entamoeba dispar (OR 0·56, 95% CI 0·42–0·74) and Giardia intestinalis (0·64, 0·51–0·81), but not for Blastocystis hominis (1·03, 0·87–1·23), and Cryptosporidium spp (0·68, 0·17–2·68). Water treatment was associated with significantly lower odds of B hominis (0·52, 0·34–0·78), E histolytica or E dispar (0·61, 0·38–0·99), G intestinalis (0·63, 0·50–0·80), and Cryptosporidium spp infections (0·83, 0·70–0·98). Interpretation Availability and use of sanitation facilities and water treatment is associated with lower odds of intestinal protozoa infections. Interventions that focus on water and sanitation, coupled with hygiene behaviour, should be emphasised to sustain the control of intestinal protozoa infections. Funding Swiss National Science Foundation (project numbers PBBSP3-146869 and P300P3-154634), Medicor Foundation, European Research Council (614739-A_HERO).
We present an agenda for schistosomiasis elimination that defines tools, strategies and guidelines and highlights current knowledge gaps. Our agenda is motivated by past successful control and ...elimination efforts and should assist national control programmes to move progressively from morbidity control towards elimination. Display omitted
▶ Elimination of schistosomiasis is an achievable and desirable goal. ▶ We present tools, strategies and guidelines of a schistosomiasis elimination agenda. ▶ Preventive chemotherapy must be complemented by transmission control. ▶ Political will and commitment and intersectoral collaboration are essential features. ▶ An internationally accepted mechanism of confirmation of elimination is required.
It is time to raise global awareness to the possibility of schistosomiasis elimination and to support endemic countries in their quest to determine the most appropriate approaches to eliminate this persistent and debilitating disease. The main interventions for schistosomiasis control are reviewed, including preventive chemotherapy using praziquantel, snail control, sanitation, safe water supplies, and behaviour change strategies supported by information, education and communication (IEC) materials. Differences in the biology and transmission of the three main Schistosoma species (i.e. Schistosoma haematobium, S. mansoni and S. japonicum), which impact on control interventions, are considered. Sensitive diagnostic procedures to ensure adequate surveillance in areas attaining low endemicity are required. The importance of capacity building is highlighted. To achieve elimination, an intersectoral approach is necessary, with advocacy and action from local communities and the health community to foster cooperative ventures with engineers, the private sector, governments and non-governmental organizations specialized in water supply and sanitation. Examples of successful schistosomiasis control programmes are reviewed to highlight what has been learnt in terms of strategy for control and elimination. These include St. Lucia and other Caribbean islands, Brazil and Venezuela for S. mansoni; Saudi Arabia and Egypt for both S. mansoni and S. haematobium; Morocco, Tunisia, Algeria, Mauritius and the Islamic Republic of Iran for S. haematobium; Japan and the People's Republic of China for S. japonicum. Additional targets for elimination or even eradication could be the two minor human schistosome species S. guineenisis and S. intercalatum, which have a restricted distribution in West and Central Africa. The examples show that elimination of schistosomiasis is an achievable and desirable goal requiring full integration of preventive chemotherapy with the tools of transmission control. An agenda for the elimination of schistosomiasis would aim to identify the gaps in knowledge, and define the tools, strategies and guidelines that will help national control programmes move towards elimination, including an internationally accepted mechanism that allows verification/confirmation of elimination.
Summary Non-communicable diseases dominate the public health arena in China, yet neglected tropical diseases (NTDs) are still widespread and create a substantial burden. We review the geographical ...distribution, prevalence, and epidemic characteristics of NTDs identified in China caused by helminths, protozoa, bacteria, and viruses. Lymphatic filariasis was eliminated in 2007, but schistosomiasis still affects up to 5% of local village residents in some endemic counties with around 300 000 people infected. China harbours more than 90% of the world's burden of alveolar echinococcosis and food-borne zoonoses are emerging. In 2010, the overall prevalence of soil-transmitted helminth infections caused by Ascaris lumbricoides , Trichuris trichiura , and hookworm was 11·4%, with 6·8% of these infections caused by A lumbricoides. Corresponding figures for food-borne trematodiasis, echinococcosis, and cysticercosis are more than 5%. Dengue, leishmaniasis, leprosy, rabies, and trachoma exist in many areas and should not be overlooked. Transmission of vector-borne diseases can be interrupted; nevertheless, epidemics occur in remote areas, creating a challenge for surveillance and control. Rigorous surveillance, followed by immediate and integrated response packages tailored to specific social and ecological systems, is essential for progress towards the elimination of NTDs in China.
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