Schistosomiasis Control Research Articles

Models for predicting bulinids species habitats in southwestern Nigeria

BackgroundSchistosomiasis prevalence is high in southwestern Nigeria and planorbids of the genus Bulinus had been implicated in the transmission of the disease in the area. The knowledge of species distribution in relation to environmental variables will be auspicious in planning control strategies. MethodsSatellite imagery and geographic information system (GIS) were used to develop models for predicting the habitats suitable for bulinid species. Monthly snail sample collection was done in twenty-three randomly selected water contact sites using the standard method for a period of two years. Remotely sensed variables such as Land Surface Temperature (LST), Normalized Difference Vegetation Index (NDVI) were extracted from Landsat TM, ETM+; Slope and Elevation were obtained from digital elevation model (DEM) while Rainfall was retrieved from European Meteorology Research Program. These environmental factors and snail species were integrated into QGIS to predict the potential habitats of different bulinid species using an exploratory regression model. ResultsThe following environmental variables: flat-moderate slope (0.01–15.83), LST (21.1 °C-23.4 °C), NDVI (0.19–0.52), rainfall (> 1569.34 mm) and elevation (1–278 m) contributed to the model used in predicting habitat suitable for bulinids snail intermediate hosts. Exploratory regression models showed that LST, NDVI and slope were predictors of Bulinus globosus and Bulinus jousseaumei; elevation, LST, rainfall and slope were predictors of Bulinus camerunensis; rainfall, NDVI and slope were predictors of B. senegalensis while NDVI and slope were predictors of Bulinus forskalii in the area. Bulinids in the forskalii group showed clustering in middle belt and south. The predictive risk map of B. jousseaumei was similar to the pattern described for B. globosus, but with a high R-square value of 81%. ConclusionThe predictive risk models of bulinid species in this study provided a robust output for the study area which could be used as base-line for other areas in that ecological zone. It will be useful in appropriate allocation of scarces resources in the control of schistosomiasis in that environment.

Nanoemulsion of Sideroxylon obtusifolium as an Alternative to Combat Schistosomiasis.

Schistosomiasis is caused by the intestinal parasite Schistosoma mansoni. Individuals are affected by schistosomiasis when they are exposed to aquatic environments contaminated with Schistosoma cercariae that emerged from the infected intermediate host mollusk of the genus Biomphalaria. The WHO recommends using molluscicidal products to reduce the snail population and disease transmission. The WHO encourages the search for alternative substances in schistosomiasis control. Natural products are seen as a promising alternative because they are abundant in countries where schistosomiasis is endemic and have many different substances in their extracts, impairing cases of resistance. Therefore, the nanoemulsion effect of a butanol-soluble fraction of Sideroxylon obtusifolium leaves was evaluated against three study points in the biological cycle of the disease, that is, adults and young Biomphalaria glabrata, spawning by the host mollusk, and infectious larvae of the parasite. Extract-SOB (butanol fraction) and nano-SOB (nanoemulsion) demonstrated promising activity in adult B. glabrata population control with an LC50 of 125.4 mg/L, an LC90 of 178.1 mg/L, an LC50 of 75.2 mg/L, and an LC90 of 97 mg/L. Nano-SOB presented greater potency against young B. glabrata, with an LC90 of 72.1 mg/L and an LC50 of 58.3 mg/L. Still, relevant activity against S. mansoni cercariae was eliminated in 4 h (LC90: 34.6 mg/L). Nano-SOB reduced viable spawning by approximately 30% at 178.1 and 97 mg/L. Referring to most substances in this extract, quercetin-3-rhamnosyl-(1-6)-galactoside and hyperoside may cause low environmental toxicity and human toxicity according to in silico analysis. Thus, nano-SOB is a promising agent to combat B. glabrata population growth and schistosomiasis transmission.

The prophylactic and anti-fibrotic activity of phthalimido-thiazole derivatives in schistosomiasis mansoni.

Schistosomiasis mansoni is considered a serious public health problem. As praziquantel is the only drug recommended by the World Health Organization for the treatment and control of schistosomiasis, the development of new drugs is of great significance. In this work, we present the antischistosomal activity of a small set of phthalimido-thiazole derivatives against Schistosoma mansoni. The effects of those derivatives on the viability of larvae juveniles and adult parasites, production and development of eggs, mortality of schistosomules in vitro by counting worms, and stages of eggs of infected animals in acute and chronic phases were evaluated, resulting in the identification of new multistage antischistosomal compounds. Additionally, a study of liver fibrogenesis was released. The phthalimido-thiazole derivatives, compounds 2b-d, 2h-j, had shown activity on schistosomules, achieving 100% mortality even at 5mg/mL, in the first 24h. In the chronic phase of schistosomiasis infection, compound 2i promoted a reduction in the number of immature eggs, an increase in the number of non-viable parasite eggs, a reduction in the average number of eggs in the liver and intestine, decrease in the levels of hydroxyproline in the liver, and a reduction in the areas of hepatic fibrosis. This compound also promoted an increase of IL-10 and a reduction in the level of TNF-α in the liver. Accordingly, the phthalimide-thiazole scaffold is a new starting point for the development of multistage compounds that affect S. mansoni viability, egg formation, and production.

Community-wide prevalence and intensity of soil-transmitted helminthiasis and Schistosoma mansoni in two districts of Sierra Leone.

In Sierra Leone, nationally powered school-based surveys have documented significant progress in the control of soil-transmitted helminthiasis (STH) and schistosomiasis. In order to assess the district-level prevalence and intensity of infection among key at-risk groups outside of school age children (SAC), we conducted a multi-stage, cluster-sample household survey in Bo and Kenema districts in May 2018. From both districts, we examined 1,282 pre-school age children (PSAC), 730 school age children (SAC), and 517 adults over 14 years (including 387 women of reproductive age, or WRA) for STH and Schistosoma mansoni infection using Kato Katz technique. In Bo, STH prevalence was 8.0% (95% Upper Confidence Limit 10.2%) in PSAC, 6.4% (95% Upper Confidence Limit 9.0%) in SAC, 14.1% (95% Upper Confidence Limit 17.4%) in all adults and 11.9% (95% Upper Confidence Limit 17.4%) in WRA. In Kenema, STH prevalence was 18.1% (95% Upper Confidence Limit 20.5%) in PSAC, 17.3% (95% Upper Confidence Limit 20.7%) in SAC, and 16.9% (95% Upper Confidence Limit 20.5%) in all adults and 16.9% (95% Upper Confidence Limit 22.6%) in WRA. Hookworm species were the most prevalent of STH in both districts overall. The overall prevalence of S. mansoni was <10% in Bo and <20% in Kenema, and was similar across age groups. No moderate or heavy intensity STH infections or heavy intensity S. mansoni infections, as per World Health Organization (WHO) classification, were detected in either district. Sanitation variables, such as toilet access and quality, were independently associated with STH and S. mansoni infection. In Kenema, STH prevalence in SAC was within the WHO-defined range for annual treatment, whereas a previous nationally-powered survey estimated it to lie within the range of treatment once per two years. By utilizing community-based sampling, we were able to assess prevalence among WRA and make recommendations based on current guidance from WHO. To continue toward elimination of STH and S. mansoni as a public health problem, resources should be mobilized to increase access to and uptake of improved sanitation at community and household levels.

Implication of serum Nitric oxide and IgE in urinary schistosomiasis: The case of Bamendjing, Cameroon

BackgroundUrinary schistosomiasis (US), also known as bilharziasis is a waterborne parasitic infection most common in rural areas of developing countries. The infection is associated with haematuria but little or nothing is known about its association with other urinary parameters, induction of Nitric Oxide (NO) and IgE production around the Bamendjing Dam an area highly suspected of Schistosoma haematobium infections. The study sought to address this problem for possible future interventions and control. Materials and methodsUrine samples were collected from 301 randomly selected participants and analysed for the presence of S. haematobium using the syringe filtration concentration method. Sera from patients infected with S. haematobium and also from some uninfected individuals were analysed for IgE and NO using ELISA and colorimetric methods respectively. FindingsThe results showed a prevalence of 16.9% (51/301). Sixty percent of the 49 patients with nitrite in their urine, were infected with urinary schistosomiasis (US) (30/49; p = 0.00). Meanwhile only 40% of the 15 patients with bilirubinuria were infected with US (6/15; p = 0.0241). The risk of patients with US having leucocytes and nitrites was high (OR of 1.3 and 1.7 respectively). Total IgE serum levels were significantly higher in patients with US (648.872 ± 223.142) compared to uninfected individuals (275.682 ± 181.674) (p = 0.00). Infected persons had heightened mean NO levels (2,583,617.647 ± 1,100,678.786) than non-infected participants (1,689,766.667 ± 1,163,084.729). Urinary Schistosomiasis in association with urinary parameters had a significant impact on mean IgE levels (F = 4.248, p = 0.022). Patients infected with Urinary Schistosomiasis alone had significantly higher mean total IgE levels than non-infected participants (p = 0.004). ConclusionApart from haematuria, this study has demonstrated that Urinary Schistosomiasis is prevalent among inhabitants around the Bamendjing Dam and results in an increase of other urine parameters such as leucocytes and nitrates and high levels of serum NO and total serum IgE in patients. These parameters are important in the screening of patients for treatment and control of urinary schistosomiasis.

Schistosomiasis and Water Related Activities: A Major Road Block to Disease Control among School-Aged Children in Endemic Communities along Oyan Dam in Ogun State, Nigeria

Majority of sub-Saharan countries have restricted access to potable water supply, leaving them with the option of utilizing natural water bodies for their domestic chores which are polluted with advance stages of the schistosome parasite. This study was investigated to determine the water contacts usage among school pupil in Abuleoriowo and AbuleTitun along Oyan Dam in Ogun State, Nigeria. A structured questionnaire was employed in collecting data of school pupil of 0-19 and their house hold. Result from the study indicates that schistosomiasis is endemic in the study communities with a high risk to source of 35 (46.7) % and 38 (50.7) % in Abule-Titin and Abule-Oriowo respectively. There was no significant difference between male and female, the result shows that 40(53.3%) females and 37(49.3%) male were exposed to water contact activities. Children are being vulnerable to Schistosomiasis as consequences of frequent water contact which affect the schistosomiasis control in school minor in the study areas. The communities living in Schistosome endemic area should be educated on important role of improved water, sanitation, and hygiene as pivotal to sustained intervention for the mitigation of schistosomiasis, whereas attitudes, and practices of water contact among school children should be discourage through community sensitization in order to mitigate their passive vulnerability to infective water.

Comparing the accuracy of two diagnostic methods for detection of light Schistosoma haematobium infection in an elimination setting in Wolaita Zone, South Western Ethiopia.

Reagent urinalysis dipstick and filtration have been recommended diagnostic methods for the detection of urogenital schistosomiasis. However, the accurate diagnosis of light infections using these methods presents a major challenge. This study evaluates the diagnosis accuracy of light infection with Schistosoma haematobium in study participants living in Wolaita Zone, an area targeted for sustainable control of Schistosomiasis, and ultimately interrupt transmission. Urine samples were collected from children and adults in surveys carried out during baseline and longitudinal sentinel site surveys conducted from 2018 to 2020. All urine samples were tested using a reagent urinalysis dipstick test (Haemastix) to detect microhaematuria with reference urine filtration technique as a proxy for S. haematobium infection. Sensitivity and specificity were determined in diagnosing urogenital schistosomiasis. Cohen's Kappa statistics was done for the agreement of these diagnostic methods. A total of 12,102 participants were enrolled in the current baseline study. Among them, 285 (2.35%) samples tested positive for microhaematuria and 21 (0.20%) positive for S. haematobium eggs. A total of 4,357 samples were examined in year 1 and year 2 using urine dipsticks, and urine filtration 172 (3.95%) and 2 (0.05%) were positive for microhaematuria and S. haematobium eggs. The reagent urinalysis dipsticks showed the highest sensitivity and specificity for diagnosing light intensity of infection,100% (95% CI:85.18-100.00) and 97.4% (95% CI: 97.10-97.60), respectively. There is a slight agreement between the two methods (Kappa = 0.09, 95% CI: 0.01-0.18). The present study revealed very low prevalence and light intensity of S. haematobium infections. The study also highlights that the dipstick test is considered a useful adjunct diagnostic tool for population-based control of urogenital schistosomiasis.

Prevalence and risk factors of urogenital schistosomiasis among under-fives in Mtama District in the Lindi region of Tanzania.

IntroductionDespite the ongoing intervention for schistosomiasis control among school-age children in the Lindi region of Tanzania, urogenital schistosomiasis continues to be a public health problem, presumably because other at-risk populations are not covered in praziquantel deworming campaigns. Evidence shows that under-fives become infected in their early life hence the need to understand the disease profile and the risk factors for exposure to infection so as to plan effective control strategies in this group. This study examined the prevalence and risk factors of urogenital schistosomiasis among under-fives in the Mtama district, Lindi region of Tanzania.Methodology/Principal findingsA quantitative community-based cross-sectional study was carried out among 770 participants (385 under-fives and their 385 parents/guardians) in the Mtama district to investigate the burden and the risk factors associated with S. haematobium infection. A single urine specimen was collected from the under-fives and tested for macro and microhaematuria, presence of S. haematobium ova, and intensity of infection. A structured questionnaire gathered on risk factors for S. haematobium exposure in under-fives from their parents/guardians. Data analysis was performed using descriptive statistics, chi-square test, and logistic regression.Prevalence of S. haematobium ova was 16.9%, and that of macro and microhaematuria was 6% and 17.9%, respectively. Of the 65 positive under-fives, 49 (75.4%) 95% CI 65.4–86.3 had a light infection intensity, and 16 (24.6%) 95% CI 13.7–35.5 had a heavy infection intensity. Among the assessed risk factors, the parents/guardians habit of visiting water bodies for domestic routines (AOR: 1.44, 95% CI: 1.13–1.74), especially the river (AOR: 6.00, 95% CI: 1.20–35.12), was found to be a significant risk factor for infection of S. haematobium in under-fives.Conclusion/SignificanceA moderate prevalence of S. haematobium was found among the under-fives conceivably with adverse health events. The infected under-fives could be a source of continuity for transmission in the community. An intervention that covers this group is necessary and should be complemented with regular screening, health education campaigns, and an adequate supply of safe water.

An assessment of implementation and effectiveness of mass drug administration for prevention and control of schistosomiasis and soil-transmitted helminths in selected southern Malawi districts

BackgroundMass drug administration (MDA) is one of the key interventions recommended by WHO for prevention and control of neglected tropical diseases (NTD). In Malawi, MDA is widely carried out annually since 2009 for prevention and control of schistosomiasis and soil-transmitted helminths (STH). No study has been carried out to assess effectiveness of the MDA approach and to document perceptions of health providers and beneficiaries regarding use of MDA. This study was done to understand how well MDA is being implemented and to identify opportunities for improvement in MDA delivery in Malawi.MethodsDesigned as a cross-sectional and multi-methods research, the study was carried out in three southern Malawi districts of Chiradzulu, Mangochi and Zomba. In each district, four health centres and 16 villages were randomly selected to participate. A mixed-methods approach to data collection focusing on quantitative data for coverage and knowledge, attitudes and practices assessments; and qualitative data for assessing perceptions of health providers and beneficiaries regarding MDA was used. Quantitative data were processed and analyzed using IBM SPSS software version 26 while qualitative data were analysed using NVivo 12 for Windows.ResultsKnowledge levels about schistosomiasis and STH in the districts varied according to disease aspects asked about. Majority are more knowledgeable about what schistosomiasis is (78%) and whether STH are treatable with drugs (97%); with least knowledgeable about the organism that transmits schistosomiasis (18%), types of schistosomiasis (11%) and what causes STH (20%). In 2018 and 2019 the districts registered high coverage rates for praziquantel and albendazole using community-based MDA (73–100%) and using school-based MDA (75–91%). Both the health authorities and community members perceived the MDA approach as good because it brings treatment closer to people.ConclusionWith the high MDA coverage obtained in communities and schools, the effectiveness of MDA in the target districts is satisfactory. There are, however, several challenges including disproportionate knowledge levels, which are hampering progress towards attainment of the 2030 global NTD goals. There is a need for promotion of community participation and partnerships as well as implementation of other recommended interventions for sustainable prevention and control of schistosomiasis and STH.

Schistoscope: An Automated Microscope with Artificial Intelligence for Detection of Schistosoma haematobium Eggs in Resource-Limited Settings.

For many parasitic diseases, the microscopic examination of clinical samples such as urine and stool still serves as the diagnostic reference standard, primarily because microscopes are accessible and cost-effective. However, conventional microscopy is laborious, requires highly skilled personnel, and is highly subjective. Requirements for skilled operators, coupled with the cost and maintenance needs of the microscopes, which is hardly done in endemic countries, presents grossly limited access to the diagnosis of parasitic diseases in resource-limited settings. The urgent requirement for the management of tropical diseases such as schistosomiasis, which is now focused on elimination, has underscored the critical need for the creation of access to easy-to-use diagnosis for case detection, community mapping, and surveillance. In this paper, we present a low-cost automated digital microscope—the Schistoscope—which is capable of automatic focusing and scanning regions of interest in prepared microscope slides, and automatic detection of Schistosoma haematobium eggs in captured images. The device was developed using widely accessible distributed manufacturing methods and off-the-shelf components to enable local manufacturability and ease of maintenance. For proof of principle, we created a Schistosoma haematobium egg dataset of over 5000 images captured from spiked and clinical urine samples from field settings and demonstrated the automatic detection of Schistosoma haematobium eggs using a trained deep neural network model. The experiments and results presented in this paper collectively illustrate the robustness, stability, and optical performance of the device, making it suitable for use in the monitoring and evaluation of schistosomiasis control programs in endemic settings.

Epidemiological trends for human schistosomiasis prevalence in Hubei Province from 2004 to 2018 based on Joinpoint regression analysis

To analyze the trends of human schistosomiasis prevalence in Hubei Province from 2004 to 2018, so as to provide the evidence for formulating the schistosomiasis elimination strategy in the province. All data pertaining to human schistosomiasis prevalence in Hubei Province were collected from 2004 to 2018, and the trends for changes in seroprevalence, egg-positive rate and prevalence of human Schistosoma japonicum infection were analyzed using a Joinpoint regression model. Both of the numbers of residents seropositive and egg-positive for S. japonicum infections appeared a tendency towards a decline in Hubei Province from 2004 to 2018, and the prevalence of human S. japonicum infections reduced from 6.85% in 2004 to 0 in 2018. Joinpoint regression analysis showed that the prevalence of human S. japonicum infections appeared an overall tendency towards a reduction in Hubei Province from 2004 to 2018 [average annual percent change (AAPC) = -24.1%, P < 0.01], and the trends for the reduction were both significant during the period from 2004 to 2006 [annual percent change (APC) = -35.1%, P < 0.01] and from 2006 to 2018 (APC = -22.1%, P < 0.01). The prevalence of human S. japonicum infections appeared a tendency towards a decline in islet (AAPC = -25.1%, P < 0.01), inner embankment (AAPC = -26.4%, P < 0.01) and hilly subtypes of schistosomiasis-endemic areas (AAPC = -32.5%, P < 0.01) of Hubei Province from 2004 to 2018, and the prevalence all appeared a tendency towards a decline during the infection control stage (from 2004 to 2008), the transmission control stage (from 2009 to 2013) and the transmission interruption stage (from 2014 to 2018) (AAPC = -28.0%, -24.4% and -63.8%, all P values < 0.01). The seroprevalence of human S. japonicum infections appeared an overall tendency towards a decline in Hubei Province from 2004 to 2018 (AAPC = -14.5%, P < 0.01), and the trends for the reduction were both significant during the period from 2004 to 2012 (APC = -8.4%, P < 0.01) and from 2012 to 2018 (APC = -22.1%, P < 0.01). In addition, the egg-positive rate of human S. japonicum infections appeared an overall tendency towards a decline in Hubei Province from 2004 to 2018 (AAPC = -30.6%, P < 0.05), and the trend for the reduction was significant during the period from 2007 to 2014 (APC = -15.5%, P < 0.01). The prevalence of human schistosomiasis appeared a tendency towards a decline in Hubei Province from 2004 to 2018, and the islet and inner embankment subtypes of endemic areas are a high priority for schistosomiasis control during the stage moving towards elimination in Hubei Province.

Factors Controlling the Distribution of Intermediate Host Snails of Schistosoma in Crater Lakes in Uganda: A Machine Learning Approach

Schistosomiasis affects over 700 million people globally. 90% of the infected live in sub-Saharan Africa, where the trematode species Schistosoma mansoni and S. haematobium transmitted by intermediate hosts (IH) of the gastropod genera Biomphalaria and Bulinus are the major cause of the human disease burden. Understanding the factors influencing the distribution of the IH is vital towards the control of human schistosomiasis. We explored the applicability of a machine learning algorithm, random forest, to determine significant predictors of IH distribution and their variation across different geographic scales in crater lakes in western Uganda. We found distinct variation in the potential controls of IH snail distribution among the two snail genera as well as across different geographic scales. On the larger scale, geography, diversity of the associated mollusk fauna and climate are important predictors for the presence of Biomphalaria, whereas mollusk diversity, water chemistry and geography mainly control the occurrence of Bulinus. Mollusk diversity and geography are relevant for the presence of both genera combined. On the scale of an individual crater lake field, Biomphalaria is solely controlled by geography, while mollusk diversity is most relevant for the presence of Bulinus. Our study demonstrates the importance of combining a comprehensive set of predictor variables, a method that allows for variable selection and a differentiated assessment of different host genera and geographic scale to reveal relevant predictors of distribution. The results of our study contribute to making realistic predictions of IH snail distribution and schistosomiasis prevalence and can help in supporting strategies towards controlling the disease.

Endemic situation of schistosomiasis in Suzhou City from 2010 to 2020

To analyze the endemic status of schistosomiasis in Suzhou City from 2010 to 2020, so as to provide the evidence for formulating the future schistosomiasis control strategy. The data pertaining to the endemic status of schistosomiasis in Suzhou City from 2010 to 2020 were retrieved from the annual schistosomiasis control report, the information management platform of schistosomiasis (parasitic diseases) in Jiangsu Province and the Parasitic Diseases Control Information Management System of Chinese Center for Disease Control and Prevention, including snail survey data, snail control data and schistosomiasis examination data, and were retrospectively reviewed. Differences of proportions were tested for statistical significance with chi-square test, and the trends in proportions were evaluated using the chi-square test for trends. Elimination of schistosomiasis was achieved in Suzhou City in 2018, and there were 3.528 9 million residents living in schistosomiasis-endemic villages of 81 townships in 9 counties. A total of 707 600 labor-days were used for snail survey in 11 586 village-times in Suzhou City from 2010 to 2020, covering 18 572.73 hm2, and snail habitats were detected with an area of 68.61 hm2, including emerging snail habitats of 37.30 hm2. A total of 23 144 snails were dissected, and no Schistosoma japonicum infection was detected. Reemerging and emerging snail habitats were predominantly found in inlands. During the period from 2010 to 2020, snail control was performed in Suzhou City for 71 000 labor-times, and snail control was done covering 269.34 hm2 through chemical treatment and covering 3.48 hm2 through environmental improvements. A total of 674 002 person-times received serological tests for S. japonicum infections in Suzhou City from 2010 to 2020, with seroprevalence of 0.38%, and a total of 33 835 person-times received stool examinations, with no egg-positives identified. The sero-prevalence of S. japonicum infections appeared an overall tendency towards a rise in Suzhou City from 2010 to 2020 (χ2 = 129.48, P < 0.001). The sero-prevalence of S. japonicum infections appeared high among local residents in 2016, and remained stable in other years, while the sero-prevalence of S. japonicum infections appeared an overall tendency towards a rise among mobile populations (χ2 = 54.11, P < 0.001). There were 278 800 and 175 202 serological tests among local residents and mobile populations in Suzhou City from 2013 to 2020, and 0.50% and 0.35% sero-prevalence rates were detected, respectively. The sero-prevalence of S. japonicum infections was significantly higher among local residents than among mobile populations in Suzhou City (χ2= 54.76, P < 0.001). There is a risk of rebound of schistosomiasis in Suzhou City. Integrated control should be reinforced to prevent the risk of rebound of schistosomiasis in Suzhou City.

Schistosomiasis at the Crossroad to Elimination: Review of Eclipsed Research with Emphasis on the Post-Transmission Agenda.

While chronic schistosomiasis is pathologically well defined, the acute form of the disease is less well understood. It is generally agreed that early lesions, such as lung nodules and bladder polyps, are reversible, which impedes identification of the time elapsed since exposure. The intermediate stage between the acute and the chronic forms of schistosomiasis requires further investigation, as does the clinical stage due to lesions remaining after treatment. With current schistosomiasis control efforts gradually progressing to elimination, there is a need to focus on post-transmission schistosomiasis, which not only refers to remaining lesions from previous infections, but also accounts for the potential presence of surviving worms after treatment. This issue is particularly salient for migrants from endemic to non-endemic countries and should be kept in mind for returning expatriates from schistosomiasis-endemic countries. Negative stool examination or urine filtration are generally taken as indicative of cure since rectoscopy for Schistosoma mansoni infection, or cystoscopy for S. haematobium infection, are rarely performed. However, pathology of affected organs may persist indefinitely, while potentially remaining live worms could produce additional pathology. Hence, post-transmission schistosomiasis can prevail for years after elimination of the disease, and thus, warrant further attention.

Contrasting epidemiology of urogenital schistosomiasis among pastoral communities surrounding three Ramsar wetland in Nigeria.

Suspected changes in the epidemiology of schistosomiasis due to several hybridization reports between human and livestock Schistosoma speciesin Africa calls for epidemiological investigations among potential high-risk groups and sites. Althoughthe use of wetlands for pastoralism has been linked to schistosomiasis, there is limited information on the epidemiology of the disease among pastoralists in Nigeria. In this study, urine samples from 355 participants from pastoral communities settled around three Ramsar wetlands (Wetlands of International Importance) in Nigeria, (Dagona Sanctuary, Maladumba, and Pandam-Wase) were screened for the eggs of Schistosoma haematobium. Only participants in the Dagona Sanctuary were infected with 34.2% prevalence. Macrohematuria was however observed in some individuals at the Dagona Sanctuary wetland (2.5%) and Maladumba (2.8%). Regular praziquantel administration, functional health care facilities and awareness about schistosomiasis were contributory factors to the contrasting epidemiology of the disease among the study population. Schistosomiasis control requires the inclusion of pastoral and nomadic communities in mass drug administration of praziquantel based on a community-directed intervention strategy.

Schistosoma japonicum translationally controlled tumour protein, which is associated with the development of female worms, as a target for control of schistosomiasis

Schistosomiasis is a globally important helminthic disease of both humans and animals, and is the second most common parasitic disease after malaria. Although praziquantel is extensively used for treatment of parasitic diseases, drug resistance has been reported. Therefore, new drugs and effective vaccines are needed for continuous control of schistosomiasis. Eggs produced by schistosomes are responsible for the occurrence and spread of schistosomiasis. Revealing the reproductive mechanism of schistosomes will help to control this disease. In this study, the proteomic profiles of single-sex infected female worms and bisexual infected mature female worms of Schistosoma japonicum at 18, 21, 23 and 25 days p.i. were identified with isobaric tags for relative quantitation-coupled liquid chromatography–tandem mass spectrometry. Differentially expressed proteins were subsequently used for bioinformatic analysis. Six highly expressed differentially expressed proteins in mature female worms were selected and long-term interference with small interfering RNA (siRNA) was conducted to determine biological functions. SiRNA against S. japonicum translationally controlled tumour protein (SjTCTP) resulted in the most significant effect on the growth and development of MF worms. Sjtctp mRNA expression gradually increased over time with a high level of expression maintained at 25–42 days p.i., while levels were significantly higher in mature female worms than male and SF worms. The subsequent animal immune protection experiments showed that recombinant SjTCTP (rSjTCTP) reduced the number of adults by 44.7% (P < 0.01), average egg burden per gram of liver by 57.94% (P < 0.01), egg hatching rate by 47.57% (P < 0.01), and oviposition of individual females by 43.16%. rSjTCTP induced higher levels of serum IgG, IL-2, and IL-10 in mice. Collectively, these results show that SjTCTP is vital to reproduction of female worms and, thus, is a candidate antigen for immune protection.

Efforts to eliminate schistosomiasis in Hubei province, China: 2005–2018

BackgroundThe Hubei province is one of the most schistosomiasis-epidemic-prone provinces in China. A series of strategies were adopted by the government to curb the rebound schistosomiasis endemic status that has prevailed since the early 2000s. This study aimed to elucidate the trends of schistosomiasis transmission and to appraise the effectiveness of the integrated control strategy in lake and marshland areas. MethodsSurveillance data of schistosomiasis in the Hubei province between 2005 and 2018 were analyzed, including conventional health control measures, integrated strategies, and measures that focused on the infection source. According to the local annual plan for schistosomiasis control in endemic counties, previous measures were human and snail control and surveillance. Residents aged 6–65 years were screened by an immunological detection method called indirect hemagglutination assay (IHA) after the transmission season each year. All residents who tested positive were then asked to provide a fecal sample for examination by the miracidium hatching technique (MHT) to detect the presence of schistosomes. Moreover, systematic snail surveys were conducted as a part of the combined environmental sampling method. The latter included integrated strategies and measures that focused on the infection source. Bovine stool samples were also collected and concurrently assessed using the MHT by the agriculture department, river-hardening slope protection was constructed by the water conservancy department, and forestation promotion was conducted by the forest department. The effectiveness of the integrated control strategy was assessed using two indicators of resident and livestock infection rates and three indicators of snail epidemics across all endemic areas. ResultsFrom 2005 to 2018, a total of 28. 46 million and 2. 05 million residents were assessed by immunological (IHA) and etiological (MHT) detection techniques, respectively. Snail surveys and molluscicide application were performed in 2. 26 hectares and 0. 37 hectares, respectively. Moreover, 2. 60 million bovines were assessed by etiological detection techniques (MHT). The river-hardening slope protection project was implemented in 503 places, and 46 thousand hectares in endemic areas underwent environmental modification. Forestation was implemented at an area of 0. 15 million hectares. Between 2005 and 2018, the epidemic indicators, including resident and livestock infection rates and the infested areas and infection rate of snails, all presented downward trends. The resident infection rate decreased from 3. 78% in 2005 to 0% in 2016, which persisted through 2018. The livestock infection rate decreased from 5. 63% in 2005 to 0% in 2013, which also persisted through 2018. From 2005 to 2018, the snail-inhabited area was slightly reduced, but the area of infected snails decreased to 0 in 2012; this persisted through 2018. All counties met the goal for schistosomiasis infection control, transmission control, and disruption of schistosomiasis activity in 2008, 2013, and 2018 separately. That means the goal has been achieved in each stage. ConclusionsThe decline of the schistosomiasis epidemic rate demonstrates that the Chinese government was successful in meeting its public health goal in Hubei province. In the next decade, precision interventions must be implemented in endemic counties with a relatively low epidemic status to achieve the goals of the Outline of the Healthy China 2030 Plan. A similar strategy can be applied in other countries to eliminate schistosomiasis globally.

Public Health Policy Pillars for the Sustainable Elimination of Zoonotic Schistosomiasis

Schistosomiasis is a parasitic disease acquired through contact with contaminated freshwater. The definitive hosts are terrestrial mammals, including humans, with some Schistosoma species crossing the animal-human boundary through zoonotic transmission. An estimated 12 million people live at risk of zoonotic schistosomiasis caused by Schistosoma japonicum and Schistosoma mekongi, largely in the World Health Organization’s Western Pacific Region and in Indonesia. Mathematical models have played a vital role in our understanding of the biology, transmission, and impact of intervention strategies, however, these have mostly focused on non-zoonotic Schistosoma species. Whilst these non-zoonotic-based models capture some aspects of zoonotic schistosomiasis transmission dynamics, the commonly-used frameworks are yet to adequately capture the complex epi-ecology of multi-host zoonotic transmission. However, overcoming these knowledge gaps goes beyond transmission dynamics modelling. To improve model utility and enhance zoonotic schistosomiasis control programmes, we highlight three pillars that we believe are vital to sustainable interventions at the implementation (community) and policy-level, and discuss the pillars in the context of a One-Health approach, recognising the interconnection between humans, animals and their shared environment. These pillars are: (1) human and animal epi-ecological understanding; (2) economic considerations (such as treatment costs and animal losses); and (3) sociological understanding, including inter- and intra-human and animal interactions. These pillars must be built on a strong foundation of trust, support and commitment of stakeholders and involved institutions.

Deep Learning Segmentation of Satellite Imagery Identifies Aquatic Vegetation Associated with Snail Intermediate Hosts of Schistosomiasis in Senegal, Africa

Schistosomiasis is a debilitating parasitic disease of poverty that affects more than 200 million people worldwide, mostly in sub-Saharan Africa, and is clearly associated with the construction of dams and water resource management infrastructure in tropical and subtropical areas. Changes to hydrology and salinity linked to water infrastructure development may create conditions favorable to the aquatic vegetation that is suitable habitat for the intermediate snail hosts of schistosome parasites. With thousands of small and large water reservoirs, irrigation canals, and dams developed or under construction in Africa, it is crucial to accurately assess the spatial distribution of high-risk environments that are habitat for freshwater snail intermediate hosts of schistosomiasis in rapidly changing ecosystems. Yet, standard techniques for monitoring snails are labor-intensive, time-consuming, and provide information limited to the small areas that can be manually sampled. Consequently, in low-income countries where schistosomiasis control is most needed, there are formidable challenges to identifying potential transmission hotspots for targeted medical and environmental interventions. In this study, we developed a new framework to map the spatial distribution of suitable snail habitat across large spatial scales in the Senegal River Basin by integrating satellite data, high-definition, low-cost drone imagery, and an artificial intelligence (AI)-powered computer vision technique called semantic segmentation. A deep learning model (U-Net) was built to automatically analyze high-resolution satellite imagery to produce segmentation maps of aquatic vegetation, with a fast and robust generalized prediction that proved more accurate than a more commonly used random forest approach. Accurate and up-to-date knowledge of areas at highest risk for disease transmission can increase the effectiveness of control interventions by targeting habitat of disease-carrying snails. With the deployment of this new framework, local governments or health actors might better target environmental interventions to where and when they are most needed in an integrated effort to reach the goal of schistosomiasis elimination.

Molluscicidal and cercaricidal activities of the essential oil of Dysphania ambrosioides (L.) Mosyakin & Clemants: Implications for the control of schistosomiasis

Schistosomiasis is one of the most important tropical diseases. A fundamental strategy to control its spread is the use of natural products against its vectors, which are snails of the genus Biomphalaria. The present study evaluated the chemical composition, the molluscicidal and cercaricidal effects, and the ecotoxicity of the essential oil from the aerial parts of Dysphania ambrosioides (L.) Mosyakin & Clemants (DAEO). The essential oil was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). Molluscicidal and cercaricidal activities were determined by the immersion method. Environmental toxicity was assessed from bioassays using Artemia salina larvae and Danio rerio fish. DAEO presented a 0.8% yield. The GC-MS analysis revealed the predominance of hydrocarbon monoterpenes in the oil. A total of 32 constituents was identified, with α-terpinene (50.69%) being the major compound, followed by p-cymene (13.27%) and ascaridole (10.26%). DAEO was active against adult Biomphalaria glabrata snails and demonstrated lethal effect against Schistosoma mansoni cercariae, with LC50 values of 25.2 (22.7–27.8) and 62.4 (61.8–62.9) μg/mL, respectively. Regarding toxicity to non-target aquatic organisms, the oil showed LC50 values of 86.9 (84.7–87.6) and 18.6 μg/mL (15.5–22.8) for A. salina and D. rerio, respectively. DAEO proved to be a promising natural product for the control of schistosomiasis, acting on both the vectors and the etiological agent of the disease. However, the use of the oil is safer in transmission sites where there are no non-target organisms, as it has showed toxicity to D. rerio fish.