Endemic Schistosomiasis Research Articles

Risk factors for schistosomiasis

ABSTRACT In this review, I describe the progress in a study that focused on the risk factors for schistosomiasis around the globe for the purposes of the review. Human schistosomiasis affects 229 million people; at least 90% are in sub-Saharan Africa, and 54% are school-aged children. Schistosoma haematobium infects 112 million people, Schistosoma japonicum infects 3.1 million people, and Schistosoma mansoni infects 54 million people. Schistosomiasis can occur in endemic and non-endemic areas. A high risk of schistosomiasis can occur in, for example, preschool-aged children, school-aged children, and workers in endemic schistosomiasis areas. These people make contact with infested freshwater day by day. In addition, environmental factors and socioeconomic factors can affect the transmission of schistosomiasis. Various factors can cause the transmission of schistosomiasis, for example, climate changes and proximity to infested freshwater bodies. People with high risks for schistosomiasis need great attention for treatment and/or prevention programs. Risk factors for schistosomiasis, for example, human behavior and socioeconomic status, can affect the transmission of schistosomiasis. Many developing countries in Africa, Asia, and South America are at risk of this disease. High-risk people need special attention in programs for schistosomiasis elimination.

Schistosomiasis endemicity and its role in sexually transmitted infections – a systematic review and meta-analysis

IntroductionSchistosomiasis, a tropical parasitic disease, affects 779 million people globally, with 85% of cases in Africa. The interplay between schistosomiasis and other sexually transmitted infections (STIs) can exacerbate health burdens, but most attention has focused on interactions with HIV, neglecting coinfections with other STIs. This systematic review and meta-analysis aims to understand the role Schistosoma infections play in STIs within schistosomiasis-endemic populations.MethodsThe study is a systematic review and meta-analysis investigating the link between Schistosoma infections and STIs in endemic regions. It uses PRISMA guidelines, electronic databases, and Google Scholar to assess prevalence, associations, and heterogeneity, reducing bias using a Meta-Mar statistical tool.ResultsA quantitative synthesis of 33 articles from 1975–2024 involved 22,587 participants from 13 countries, including regions in Africa, France, and China, examining coinfections of schistosomiasis and STIs, including HIV. The pooled estimates showed a significant risk association between schistosomiasis and STIs [RR (95% CI) = 1.18, (1.13–1.24); z/t = 7.55, p<0.0001] using a fixed effect model. Cochran’s Q test (Tau2 = 0.5061, Chi2 = 476.65, df = 32, p<0.01) indicated significant heterogeneity. The Higgins I2 statistic of 93.0% (91.5%–94.7%), H = 3.86 (3.43–4.33), highlighted substantial variance between studies. Subgroup analysis showed West Africa [Weight IV = 1.7%, RR (95% CI) = 1.78 (1.28–2.47), I2 = 59%], East Africa [Weight IV = 10.5%, RR (95% CI) = 0.99 (0.86–1.13), I2 = 54%], and Southern Africa [Weight IV = 82.0%, RR (95% CI) = 1.16 (1.10–1.21), I2 = 97%] contributed significantly to the high heterogeneity in the pooled analysis. Females had a notably higher risk of STIs in the context of schistosomiasis (k = 17, RR: 1.30, 95% CI: 1.23–1.37, Q = 316.78, I2 = 94.9%), compared to males (k = 6, RR: 0.94, 95% CI: 0.77–1.15, Q = 53.44, I2 = 90.6%) and the combined group of females and males (k = 9, RR: 0.95, 95% CI: 0.88–1.02, Q = 16.38, I2 = 50.2%).ConclusionThe study found a high risk of coinfections between schistosomiasis and STIs, particularly in West and Southern Africa, confirming female genital schistosomiasis as a major risk for STIs.

Historic water quality patterns in endemic schistosomiasis regions of southern Africa: Implications for disease vector distribution

Alterations in atmospheric temperature and rainfall have a major influence on the distribution patterns of vector-borne diseases, including schistosomiasis, by changing the optimum habitat of the intermediate hosts (vectors) that transmit these diseases. Water quality degradation and the creation of artificial freshwater habitats may widen or restrict the distribution of disease vectors. Understanding the influence of water quality on ecosystems is essential in determining the environments that vectors thrive in and where potential outbreaks of the disease they carry will occur. This study aims to analyse the changes in various water quality variables between 1977 and 2009 in the Mbombela river systems and how this may have altered the presence of schistosomiasis snail vectors in these areas. Historical water quality data for the Sabie, Kaap, Komati and Crocodile rivers were obtained from the Department of Water and Sanitation monitoring stations and separated into three decades (1977–1987; 1988–1998 and 1999–2009). The Physicochemical Driver Assessment Index (PAI) was used to determine the ecological category of the rivers in each decade. A Principal Component Analysis was also created for the different river systems to identify possible changes in water quality over the 3 decades. According to the PAI, the Sabie River remained in a relatively good state while the Crocodile, Komati and Kaap rivers had a low water quality to begin with and became further degraded over the three decades. The PCAs indicated the Sabie and Crocodile rivers had increased levels of salts, nutrients and pH between 1988-1998 and 1999–2009 while the Kaap River had high salt content and pH between 1977 and 1998 and high nutrients during the decade of 1999–2009. These results indicate that there has been a change in the water quality of Mbombela river systems with notable increases in salt, pH and nutrient levels. As a result, the aquatic biota have likely been negatively affected and this poses severe impacts on the presence and abundance of schistosomiasis vectors as the snails are sensitive to changes in salinity, nutrients and pH.

Endemic status of urogenital schistosomiasis and the efficacy of a single-dose praziquantel treatment in unmapped rural farming communities in Oyo East Local Government Area, Oyo State, Nigeria.

Schistosomiasis is endemic in Nigeria, and the treatment is largely concentrated on children enrolled in schools. Consequently, the coverage of non-enrolled school-aged children is often neglected. Ajagba and Awosan are two communities in Nigeria that have never had any control intervention. Hence, this survey was designed to determine the endemicity of urogenital schistosomiasis and to evaluate the efficacy of a single-dose praziquantel in the communities. Urine sample (10 mL) of each participant from Ajagba and Awosan communities was filtered through 12μm polycarbonate filter. The filter was placed on a microscope slide, and stained with a drop of 1% Lugol iodine solution. The stained slides were examined under the microscope and the numbers of S. haematobium eggs were counted. Water contact sites were searched for snail hosts and the snails collected were shed for Schistosoma cercariae. Data were analyzed using SPSS version 24.0 and the significance level was set at 95%. The overall prevalence of infection in the Ajagba community was 45.6% with a mean intensity of 61.1 ± 144.5 eggs/10 mL of urine, while the prevalence of infection in the Awosan community was 5.7% with a mean intensity of 1.4 ± 6.8 eggs/10 mL of urine. The school-aged children had a prevalence and mean intensity of infection of 73.1% and 111.6 ± 177.9 eggs/10 mL of urine, respectively. Following treatment, women had a higher egg reduction rate than men (p = 0.0283). Bulinus globosus were found in Ajagba but not in Awosan, with 5.7% shedding Schistosoma spp, cercariae. Urogenital schistosomiasis was hyperendemic in the Ajagba community, and hypoendemic in the Awosan community. The presence of Bulinus globosus supported the transmission of the schistosomiasis in the Ajagba community. Communities where schistosomiasis is still actively transmitted in Nigeria should be identified for effective intervention through the MDA programs.

Schistosomiasis control in Senegal: results from community data analysis for optimizing preventive chemotherapy intervention with praziquantel

BackgroundOver the past two decades, preventive chemotherapy (PC) with praziquantel (PZQ) is the major strategy for controlling schistosomiasis in Senegal. The objective of this analysis was to update the endemicity of schistosomiasis at community level for better targeting mass treatment with PZQ in Senegal.MethodsDemographic and epidemiological data from 1610 community health areas were analyzed using the schistosomiasis community data analysis tool of Expanded Special Project for Elimination of Neglected Tropical Diseases which developed by World Health Organization/Africa Office (WHO/AFRO). The tool uses a WHO/AFRO decision tree for areas without epidemiological data to determine whether mass treatment should be continued at community level. Descriptive analysis was performed.ResultsOverall, the endemicity of 1610 community health areas were updated based on the data from the district endemicity (33.5%) and the form of Join request for selected PC medicine (40.5%). Up to 282 (17.5%) and 398 (24.7%) of community health areas were classified as moderate and high endemicity. 41.1% of communities were non endemic. High endemicity was more important in Tambacounda, Saint Louis, Matam, Louga and Kedougou. A change in endemicity category was observed when data was disagregted from district level to community level. Implementation units classified non endemic were more important at community level (n = 666) compared to district level (n = 324). Among 540 areas previously classified high endemic at district level, 392 (72.6%) remained high prevalence category, while 92 (17.0%) became moderate, 43 (8.0%) low and 13 (2.4%) non-endemics at community level. Number of implementation units requiring PC was more important at district level (1286) compared to community level (944). Number of school aged children requiring treatment was also more important at district level compared to community level.ConclusionsThe analysis to disaggregate data from district level to community level using the WHO/AFRO schistosomiasis sub-district data optimization tool provide an update of schistosomiasis endemicity at community level. This study has allowed to better target schistosomiasis interventions, optimize use of available PZQ and exposed data gaps.

A compartmental model for Schistosoma japonicum transmission dynamics in the Philippines

Schistosomiasis is a chronic and debilitating neglected tropical disease (NTD), second only to malaria as one of the most devastating parasitic diseases. Caused by a parasitic flatworm of the genus Schistosoma, infection occurs when skin comes in contact with contaminated freshwater that contains schistosome-hosting snails. The disease continues to be endemic in many regions of the Philippines, where it poses a significant public health challenge due to a lack of healthcare resources. In the Philippines, additional mammalian reservoirs for the S. japonicum parasite, especially bovines such as carabaos, also facilitate the spread of schistosomiasis. We extend existing compartment models to include human, snail, bovine, and free-living Schistosoma for a comprehensive look at the transmission dynamics of the disease. Sensitivity analysis of model parameters shows that the carabaos themselves can sustain the endemicity of schistosomiasis. Thus, we consider the control method of farming mechanization to avoid contaminated freshwater sources. We find that a reduction of contaminated water contacts by at least 77% will break the transmission cycle and eliminate the disease. However, reducing the contact by about 70% will still result in decrease of human schistosomiasis prevalence to under 1% in 15 years or less. Achieving such high reduction of contact rates could be a daunting task, especially in rural areas. Still, the potential to eliminate or at least reduce the schistosomiasis prevalence should be considered an additional benefit of mechanization efforts in the Philippines.

Livestock cattle as a predictor of schistosomiasis transmission in Nigeria

Livestock cattle have been widely linked to schistosomiasis epidemiology, but little is known about its contribution to schistosomiasis transmission in Nigeria. The aim of this study is to examine the association between prevalence of schistosomiasis and livestock cattle index in Nigeria. The study's data came from three sources: the demographic and health survey (DHS), the malaria indicators survey (MIS), and the expanded special project for the eradication of neglected tropical diseases (ESPEN). Analysis of variance, correlation, and logistic regression were used to evaluate the mean difference in schistosomiasis prevalence across geopolitical zones, the relationship between schistosomiasis prevalence and livestock cattle, and the risk of schistosomiasis in each geopolitical zone when the cattle index was known, respectively. The overall relationship of the pooled data showed that schistosomiasis endemicity increased significantly with livestock cattle index (r = 0.052, P = 0.0001). Reduction in livestock cattle significantly reduced schistosomiasis transmission in the Northeast and South south in 2021 (P < 0.05). Livestock cattle was consistently a significant negative predictor of schistosomiasis in the Northeast and South-South but a consistent significant risk factor of schistosomiasis transmission in the Northwest, Southeast, Southwest in 2018 and 2021 (P < 0.05). The possibility that livestock cattle are a predictor of transmission of schistosomiasis cannot be disparaged; hence, policies that will curtail the zoonotic mode of transmission should be developed for possible future implementation.

Abundance, Distribution, and Diversity of Freshwater Snail and Prevalences of Their Infection by Cercaria of Fasciola gigantica and Schistosoma spp at Mayo-Vreck River, Far North Region of Cameroon.

Malacological and parasitological studies were conducted from April 2020 to March 2021 to determine the abundance and distribution of molluscs and cercariae of Schistosoma spp and Fasciola gigantica. Collected molluscs are exposed to strong light to induce cercarial release. Mollusc densities were higher at station 1 (Gamak) than in station 8 (Patakai), with Bellamya unicolor and Biomphalaria pfeifferi more abundant and Bulinus truncatus, B. tropicus, and B. globosus less abundant. The overall prevalence of cercariae (19.87%) is higher in station 3 (Yaye orchard), station 9 (Gougni), station 4 (Madiogo), station 5 (Madiogo pasture), and station 6 (Ziam 3). It varies significantly between 15.76% in station 8 and 25.77% in station 3, between 8.48% in B. truncatus and 25.53% in B. globosus, and between 19.27% for cercariae of Schistosoma spp and 21.60% for those of F. gigantica. Cercarial emissions in L. natalensis and B. pfeifferi were higher in hot and cold dry seasons; on the other hand, cercarial emissions in B. globosus were higher in hot dry seasons (31.48%) and rainy seasons (23.38%). Emissions of cercariae from S. haematobium are related to areas of human activity and defecation, while those of F. gigantica in L. natalensis, Schistosoma haematobium in B. tropicus, and S. mansoni in B. pfeifferi are related to grazing areas. Mayo-Vreck is a site that favors the endemicity of fascioliasis and human schistosomiasis.

Endemicity of Urogenital Schistosomiasis and Its Associated Risk Factors among Children in Danbatta, Northwestern Nigeria

Urogenital schistosomiasis, also known as bilharzias is a digenean parasitic infection, classified among the neglected tropical diseases, which has remained endemic in Nigeria, despite efforts in mass drugs administration (MDA) across the country. This study reported the endemicity of urogenital schistosomiasis and its associated risks factors among children in Danbatta, Northwestern Nigeria. A cross-sectional study was conducted among children of Danbatta, Kano State, Northwestern Nigeria. A total of 400 urine samples were collected from children in 4 conventional Primary Schools (198) and 4 Tsangaya (almajiris) schools (202). Urine sedimentation microscopy technique was used in sample analysis. A semi-structured questionnaire was used to collect socio-demographic and other exposure information to explore associated risk factors for the infection. Data were expressed in prevalence (%) and subjected to chi-square analysis at 95%CI, p≤0.05. Out of the 400 children, 282 70.5% turned out positive, with Tsangaya children having highest infection prevalence, 92.6% compared to Primary School children, and was significant with type of school (χ 2=95.611, p=0.000). Those who visited water body for irrigation purposes and those who visited daily had highest prevalence of 83.3% and 88.6% respectively. In addition, those who visited water bodies in the afternoon hours had highest prevalence of 85.6%. Urogenital schistosomiasis is hyper-endemic in Danbatta despite previous MDAs and activities that involve contact with water bodies are predisposing factors. Strategic and all-inclusive MDAs should be deployed to Danbatta to arrest the surge in endemicity of urogenital schistosomiasis.

Malacological Survey and Spatial Distribution of Intermediate Host Snails in Schistosomiasis Endemic Districts of Rwanda.

Schistosomiasis, due to S. mansoni, is prevalent in Rwanda. However, there is a paucity of information related to the abundance, species, distribution, and infectivity of Schistosoma intermediate host snails. Snails were collected from 71 sites, including lakeshores and wetlands. Snails obtained were morphologically identified, and cercariae were shed using standard procedures. Cercariae were molecularly characterized using PCR. GPS coordinates were used to generate geospatial maps of snail distribution that were overlaid with geospatial distribution of schistosomiasis among pre-school children in the same areas. Overall, 3653 snails were morphologically classified as Bulinus spp. and 1449 as Biomphalaria spp. A total of 306 snails shed cercariae, 130 of which were confirmed as S. mansoni cercaria by PCR. There was no significant difference in the proportion of S. mansoni cercariae in wetlands compared to lakeshores. Rwandan water bodies harbor an important number of snails that shed S. mansoni cercariae. Furthermore, a strong spatial correlation was observed between the distribution of schistosomiasis in children and the spatial distribution of snail infectivity with S. mansoni. The presence of Bulinus spp. Suggests a potential risk of S. haematobium, although molecular analysis did not show any current transmission of this parasite.

The Impact of Flooding on Snail Spread: The Case of Endemic Schistosomiasis Areas in Jiangxi Province, China.

Flooding is the main natural factor in snail diffusion, and it has a negative impact on schistosomiasis transmission. There are few studies on the spread and migration of snails following a flood; therefore, we aimed to investigate the influence of flooding on snail diffusion and explore the characteristics and laws of snail diffusion in Jiangxi Province. By using a retrospective survey and cross-sectional survey, the data on snail spreading in Jiangxi Province from 2017 to 2021 were collected. The distribution, nature, and area of snail spread were systematically analyzed in combination with the hydrological situation, types of region, and types of flood. From 2017 to 2021, a total of 120 snail-spread environments were found, including in 92 hilly areas and in 28 lake areas. The areas caused by flood and by other means numbered 6 and 114, respectively. The proportions of recurrence, expansion, and first-time occurrences were 43.42%, 38.16%, and 18.42%, respectively, and the 14 new snail environments were only distributed in the hilly areas. With the exception of 2018, the ratio of snail-spread areas in the hilly region was higher than that in lake region in other years. The average density of live snails was 0.0184-1.6617 no./0.1 m2 and 0.0028-0.2182 no./0.1 m2 in the hilly region. Among the 114 environments affected by floods, 86 consisted of hilly environments, including 66 spreading environments affected by rainstorm floods, and 20 rainstorm debris flow environments. There were 28 lake areas, of which 10 were in the Jiangxi section of Yangtze River and were affected by rainstorm floods. Snail spread following flooding has a certain 'lag effect,' and = simple annual changes in hydrological characteristics have little effect on the diffusion of snails or on their density = in the affected environment, but it is more closely related to local floods. The hilly environments are more susceptible to floods than the lake region, and the risk of snail spread is much higher in the hilly than in the lake region.

Precision mapping of schistosomiasis and soil-transmitted helminthiasis among school age children at the coastal region, Kenya

Accurate mapping of schistosomiasis (SCH) and soil transmitted helminths (STH) is a prerequisite for effective implementation of the control and elimination interventions. A precision mapping protocol was developed and implemented in the coastal region of Kenya by applying the current World Health Organization (WHO) mapping guide at a much lower administrative level (ward). A two-stage cluster survey design was undertaken, with 5 villages in each ward selected. From within each village 50 households were randomly selected, and a single child between the ages of 8 and 14 sampled following appropriate assent. The prevalence and intensity of infection of Schistosoma mansoni and STH were determined using the Kato-Katz method (single stool, duplicate slides) and urine filtration for S. haematobium. Of the 27,850 school age children sampled, 6.9% were infected with at least one Schistosoma species, with S. haematobium being the most common 6.1% (95% CI: 3.1-11.9), and Tana River County having highest prevalence 19.6% (95% CI: 11.6-31.3). Prevalence of any STH infection was 5.8% (95% CI: 3.7-8.9), with Lamu County having the highest prevalence at 11.9% (95% CI: 10.0-14.1). The most prevalent STH species in the region was Trichuris trichiura at 3.1% (95% CI: 2.0-4.8). According to the WHO threshold for MDA implementation, 31 wards (in 15 sub-Counties) had a prevalence of ≥10% for SCH and thus qualify for annual MDA of all age groups from 2 years old. On the other hand, using the stricter Kenya BTS MDA threshold of ≥2%, 72 wards (in 17 sub-Counties) qualified for MDA and were targeted for treatment in 2021. The precision mapping at the ward level demonstrated the variations of schistosomiasis prevalence and endemicity by ward even within the same sub-counties. The data collected will be utilized by the Kenyan Ministry of Health to improve targeting.

Urogenital schistosomiasis in three different water access in the Senegal river basin: prevalence and monitoring praziquantel efficacy and re-infection levels

BackgroundUrogenital schistosomiasis is a neglected tropical disease most prevalent in sub-Saharan Africa. In the Senegal river basin, the construction of the Diama dam led to an increase and endemicity of schistosomiasis. Since 2009, praziquantel has frequently been used as preventive chemotherapy in the form of mass administration to Senegalese school-aged children without monitoring of the treatment efficacy and the prevalence after re-infection. This study aims to determine the current prevalence of urogenital schistosomiasis (caused by Schistosoma haematobium), the efficacy of praziquantel, and the re-infection rates in children from five villages with different water access.MethodsThe baseline prevalence of S. haematobium was determined in August 2020 in 777 children between 5 and 11 years old and a single dose of praziquantel (40 mg/kg) was administered to those positive. The efficacy of praziquantel and the re-infection rates were monitored 4 weeks and 7 months after treatment, respectively, in 226 children with a high intensity of infection at baseline.ResultsAt the baseline, prevalence was low among children from the village of Mbane who live close to the Lac de Guiers (38%), moderate among those from the villages of Dioundou and Khodit, which neighbor the Doue river (46%), and very high at Khodit (90.6%) and Guia (91.2%) which mainly use an irrigation canal. After treatment, the observed cure rates confirmed the efficacy of praziquantel. The lowest cure rate (88.5%) was obtained in the village using the irrigation canal, while high cure rates were obtained in those using the lake (96.5%) and the river (98%). However, high egg reduction rates (between 96.7 and 99.7%) were obtained in all the villages. The re-infection was significantly higher in the village using the canal (42.5%) than in the villages accessing the Lac de Guiers (18.3%) and the Doue river (14.8%).ConclusionPraziquantel has an impact on reducing the prevalence and intensity of urogenital schistosomiasis. However, in the Senegal river basin, S. haematobium remains a real health problem for children living in the villages near the irrigation canals, despite regular treatment, while prevalence is declining from those frequenting the river and the Lac de Guiers.Trial registration ClinicalTrials.gov, NCT04635553. Registered 19 November 2020 retrospectively registered, https://www.clinicaltrials.gov/ct2/show/NCT04635553?cntry=SN&draw=2&rank=4

Urogenital schistosomiasis among pre-school and school aged children in four districts of north western Tanzania after 15 years of mass drug administration: Geographical prevalence, risk factors and performance of haematuria reagent strips.

Urogenital schistosomiasis remains as a public health problem in Tanzania and for the past 15 years, mass drug administration (MDA) targeting primary school children has remained as the mainstay for its control. However, after multiple rounds of MDA in highly risk groups, there are no data on the current status of Schistosoma haematobium in known endemic areas. Furthermore, the performance of commonly used diagnostic test, the urine reagent strips is not known after the decline in prevalence and intensities of infection following repeated rounds of treatment. Thus, after 15 of national MDA, there is a need to review the strategy and infection diagnostic tools available to inform the next stage of schistosomiasis control in the country. A analytical cross-sectional study was conducted between October and November, 2019 among pre-school (3-5years old) and school aged children (6-17 years old) living in four (4) districts with low (<10%) and moderate (10%-<50%) endemicity for schistosomiasis as per WHO classification at the start of the national control programme in 2005/06, with mean prevalence of 20.7%. A total of 20,389 children from 88 randomly selected primary schools participated in the study. A questionnaire was used to record demographic information. A single urine sample was obtained from each participant and visually examined for macrohaematuria, tested with a dipstick for micro-haematuria, to determine blood in urine; a marker of schistosome related morbidity and a proxy of infection. Infection intensity was determined by parasitological examination of the urine sample for S. haematobium eggs. Overall, mean infection prevalence was 7.4% (95%CI: 7.0-7.7, 1514/20,389) and geometric mean infection intensity was 15.8eggs/10mls. Both infection prevalence (5.9% versus 9%, P<0.001) and intensity (t = -6.9256, P<0.001) were significantly higher in males compared to females respectively. Light and heavy infections were detected in 82.3% and 17.7% of the positive children respectively. The prevalence of macrohaematuria was 0.3% and that of microhaematuria was 9.3% (95%CI:8.9-9.7). The sensitivity and specificity of the urine reagent strip were 78% (95%CI: 76.1-79.9) and 99.8% (95%CI: 99.7-99.9). Having light (P<0.001) and heavy infection intensities (P<0.001) and living in the study districts increased the odd of having microhaematuria. Predictors of S. haematobium infection were being male (P<0.003), microhaematuria (P<0.001), and living in the three study districts (P<0.001) compared to living at Nzega district. The findings provide an updated geographical prevalence which gives an insight on the planning and implementation of MDA. Comparing with the earlier mapping survey at the start of the national wide mass drug administration, the prevalence of S. haematobium infection have significantly declined. This partly could be attributed to repeated rounds of mass drug administration. The urine reagent strips remain as a useful adjunct diagnostic test for rapid monitoring of urogenital schistosomiasis in areas with low and high prevalence. Based on prevalence levels and with some schools having no detectable infections, review of the current blanket mass drug administration is recommended.

Vanishing Schistosomiasis Endemicity in North of Khuzestan Province, Iran: A Twenty-Five-Year Assessment

Background: Schistosomiasis, after malaria, is the second most important parasitic disease in the world in terms of morbidity and mortality and is one of the 14 neglected tropical diseases. In 2016, about 206.4 million people needed preventive treatment for the disease. Objectives: This study evaluated schistosomiasis’s incidence rate and spatial-temporal cluster distribution in the north of Khuzestan province, Iran. Methods: This cross-sectional study collected data from January 1977 to December 2001. The data of 1,390 definitive patients with Schistosoma haematobium in the north of Khuzestan province, Iran, were analyzed for the disease incidence in rural districts over five-year periods. Also, the changes in median age and sex were examined. Spatial scan statistics were used to diagnose and evaluate the spatial clusters of S. haematobium cases. The pure retrospective temporal analysis and retrospective spatial-temporal analysis were carried out to identify the temporal clusters and spatial-temporal clusters of schistosomiasis with high rates, respectively, using the discrete Poisson model. Results: The schistosomiasis incidence decreased over the years, with the last case reported in 2001. Using Kulldorff’s spatial scan method, spatial clustering showed nine high-risk areas in the north of Khuzestan province from 1977 to 2001. Besides, S. haematobium was not randomly distributed in this area. Spatial-temporal clusters identified three high-risk areas during the study period. Temporal clusters decreased from 17 months and five days to one day, and they mainly occurred in the winter and summer. Conclusions: The study indicated a zero incidence and vanishing S. haematobium endemicity in the northern region of Khuzestan province of Iran in 2002. Due to snail vectors of the disease resident in this region, the disease surveillance still needs continuation.

Prevalence and factors associated with transmission of schistosomiasis in school-aged children in South Sudan: a cross-sectional study.

IntroductionSouth Sudan is affected by a high burden of Neglected Tropical Diseases (NTDs). The country is very vulnerable to NTDs due to its favourable tropical climate and multiple risk factors. However, the distribution of the diseases and the populations at risk for the various NTDs is unknown. This paper described the distribution of schistosomiasis in 58 counties and 261 schools in South Sudan.Methodsa descriptive quantitative cross-sectional study of schistosomiasis in 58 counties in 8 states of South Sudan recruited school-aged children. Using different laboratory techniques, the children were tested for Schistosoma mansoni (S. mansoni) and Schistosoma haematobium (S. haematobium). A quantitative descriptive statistical was performed to determine the prevalence rates and the endemicity of schistosomiasis among 13,286 school-aged children.Resultsthe overall prevalence of S. mansoni and S. haematobium were 6.1% and 3.7% using Kato Katz and urine filtration concentration testing techniques. The highest state prevalence was reported in Western Equatoria for both S. mansoni (14.7%) and S. haematobium (7.3%). The age of the participants varied from 4 to 18 years; of these, children 10 to 12 years old had the highest prevalence of S. mansoni (6.8%) and S. haematobium (3.7%). The prevalence of S. mansoni (7% male vs 5% female) and S. haematobium (3.6% male vs 3.1% female) were higher in males than females. The likelihood of the prevalence of S. mansoni in males was 1.42 (95% CI:1.23, 1.64) higher than in females, while for S. haematobium, 1.36 (95% CI:1.12, 1.65) higher than in females. The prevalence of S. mansoni and S. haematobium showed a statistically significant gender difference (P< 0.05).Conclusionthe study had provided evidence of the distribution of schistosomiasis in South Sudan for policy direction and recommended annual preventive chemotherapy with praziquantel in all endemic areas.

Prevalence, intensity and endemicity of intestinal schistosomiasis and soil-transmitted helminthiasis and its associated factors among school-aged children in Southern Ethiopia

Preventive chemotherapy (PC), the main strategy recommended by the World Health Organization to eliminate soil-transmitted helminthiasis (STH) and schistosomiasis (SCH), should be strengthened through identification of the remaining SCH transmission foci and evaluating its impact to get a lesson. This study was aimed to assess the prevalence of STH/SCH infections, the intensity of infections, and factors associated with STH infection among school-aged children (SAC) in Uba Debretsehay and Dara Mallo districts (previously not known to be endemic for SCH) in southern Ethiopia, October to December 2019. Structured interview questionnaire was used to collect household data, anthropometric measurements were taken and stool samples collected from 2079 children were diagnosed using the Kato-Katz technique. Generalize mixed-effects logistic regression models were used to assess the association of STH infections with potential predictors. A P-value less than 0.05 was considered statistically significant. The prevalence of Schistosoma mansoni in the Dara Mallo district was 34.3% (95%CI 30.9–37.9%). Light, moderate, and heavy S. mansoni infections were 15.2%, 10.9%, and 8.2% respectively. The overall prevalence of any STH infection was 33.2% with a 95% confidence interval (CI) of 31.1–35.3%. The intensity of infections was light (20.9%, 11.3% & 5.3%), moderate (1.1%, 0.1% & 0.4%) and heavy (0.3%, 0% & 0%) for hookworm, whipworm and roundworms respectively. The overall moderate-to-heavy intensity of infection among the total diagnosed children was 2% (41/2079). STH infection was higher among male SAC with Adjusted Odds Ratio (AOR) of 1.7 (95%CI 1.4–2.1); occupation of the household head other than farmer or housewife (AOR = 0.5; 95%CI 0.3–0.8), middle [AOR = 1.1; 95%CI 1.0–1.3] or high [AOR = 0.7; 95%CI 0.5–0.9] socioeconomic status. Dara Mallo district was moderate endemic for S. mansoni; and it needs sub-district level mapping and initiating a deworming campaign. Both districts remained moderate endemic for STH. Evidence-based strategies supplementing existing interventions with the main focus of the identified factors is important to realize the set targets.

Reduction of testosterone levels in Schistosoma haematobium- or Schistosoma mansoni-infected men: a cross-sectional study in two schistosomiasis-endemic areas of the Adamawa region of Cameroon

BackgroundThe incidence of schistosomiasis‐induced male reproductive dysfunction and infertility is probably underestimated compared to female genital schistosomiasis. This study aimed to investigate the impact of Schistosoma haematobium or S. mansoni infection on the reproductive function of men of reproductive age in Tibati and Wouldé, two endemic schistosomiasis areas in the Adamawa region of Cameroon.MethodsA total of 89 men of reproductive age (range 14–56 years) from two localities were enrolled in the study, with 51 in Tibati and 38 in Wouldé. Each participant was submitted to a questionnaire to document data on sociodemographic and stream contact behaviors. A medical examination was performed to measure the testes’ circumference and evaluate genital tract pathologies. Stool and urine samples were collected and screened for the presence of S. haematobium or S. mansoni ova. Blood serum was used to assess the levels of transaminases and testosterone.ResultsSchistosoma haematobium was present only in Tibati, with a prevalence of 31.37%. The S. mansoni prevalence was 3.92% at Tibati and 44.71% at Wouldé. The intensity of infection was 22.12 ± 9.57 eggs/10 mL for S. haematobium and 128.10 ± 3.76 epg for S. mansoni. Serum transaminase activity and the mean testicular circumference of Schistosoma-positive individuals were close to Schistosoma-negative individuals. However, the testes size was more prominent in S. mansoni-positive individuals than in S. haematobium-positive individuals (P < 0.05). The serum testosterone levels of S. haematobium- and S. mansoni-positive men were significantly reduced by 56.07% (P < 0.001) and 51.94% (P < 0.01), respectively, in comparison to those of Schistosoma-negative men. A significant and negative correlation was established between schistosomiasis and the low serum testosterone level. Male genital tract pathologies such as scrotal abnormalities, varicocele, nodular epididymis, inguinal hernia, and hydrocele were recorded in both Schistosoma-positive and Schistosoma-negative men. However, no significant link was established between schistosomiasis infection and these pathologies.ConclusionThese results demonstrated that infection with S. haematobium or S. mansoni is associated with low production of the reproductive hormone testosterone and may be a significant cause of male infertility.

Discovery of a Hidden Schistosomiasis Endemic in the Salamat Region of Chad, Africa.

There is currently a severe paucity of rural epidemiologic data on urogenital schistosomiasis in the Republic of Chad in north-central Africa that is hindering national control strategies. Our study describes a mobile medical team's 4-year effort to collect data and provide mass therapeutic and preventive chemotherapy in the Salamat Region of Chad, a previously uninvestigated rural area. To overcome severe limitations in time, resources, support, and infrastructure, the team employed several time- and cost-saving techniques that included: (1) traveling by request and referral to utilize local knowledge to find the areas of highest need, (2) conducting convenience sampling for screening, (3) using simple but validated tools to expedite treatment and data gathering, and (4) working within cultural contexts to find and treat the most school-age children possible. The team managed a total of 11,832 patient encounters and found a 55% rate of hematuria (n=6,495) among school-age children, roughly double previous estimates. Rates of hematuria were higher in males (61%, n=3,955/6,466) than females (48%, n=2,301/4,806) and among adolescents (> 65% in all age groups aged 10 years and older). These methods outline an efficient and effective strategy implemented under real-world conditions to enact therapeutic and preventive chemotherapy campaigns in resource-limited settings by engaging village leadership and developing locally driven solutions. Our data highlight the need for continued local epidemiologic efforts to treat the substantial number of children severely affected with schistosomiasis.

Spatiotemporal heterogeneity of schistosomiasis in mainland China: Evidence from a multi-stage continuous downscaling sentinel monitoring

Objective: To determine the spatiotemporal distribution of Schistosoma (S.) japonicum infections in humans, livestock, and Oncomelania (O.) hupensis across the endemic foci of China.Methods: Based on multi-stage continuous downscaling of sentinel monitoring, county-based schistosomiasis surveillance data were captured from the national schistosomiasis surveillance sites of China from 2005 to 2019. The data included S. japonicum infections in humans, livestock, and O. hupensis. The spatiotemporal trends for schistosomiasis were detected using a Joinpoint regression model, with a standard deviational ellipse (SDE) tool, which determined the central tendency and dispersion in the spatial distribution of schistosomiasis. Further, more spatiotemporal clusters of S. japonicum infections in humans, livestock, and O. hupensis were evaluated by the Poisson model.Results: The prevalence of S. japonicum human infections decreased from 2.06% to zero based on data of the national schistosomiasis surveillance sites of China from 2005 to 2019, with a reduction from 9.42% to zero for the prevalence of S. japonicum infections in livestock, and from 0.26% to zero for the prevalence of S. japonicum infections in O. hupensis. Analysis using an SDE tool showed that schistosomiasis-affected regions were reduced yearly from 2005 to 2014 in the endemic provinces of Hunan, Hubei, Jiangxi, and Anhui, as well as in the Poyang and Dongting Lake regions. Poisson model revealed 11 clusters of S. japonicum human infections, six clusters of S. japonicum infections in livestock, and nine clusters of S. japonicum infections in O. hupensis. The clusters of human infection were highly consistent with clusters of S. japonicum infections in livestock and O. hupensis. They were in the 5 provinces of Hunan, Hubei, Jiangxi, Anhui, and Jiangsu, as well as along the middle and lower reaches of the Yangtze River. Humans, livestock, and O. hupensis infections with S. japonicum were mainly concentrated in the north of the Hunan Province, south of the Hubei Province, north of the Jiangxi Province, and southwestern portion of Anhui Province. In the 2 mountainous provinces of Sichuan and Yunnan, human, livestock, and O. hupensis infections with S. japonicum were mainly concentrated in the northwestern portion of the Yunnan Province, the Daliangshan area in the south of Sichuan Province, and the hilly regions in the middle of Sichuan Province.Conclusions: A remarkable decline in the disease prevalence of S. japonicum infection was observed in endemic schistosomiasis in China between 2005 and 2019. However, there remains a long-term risk of transmission in local areas, with the highest-risk areas primarily in Poyang Lake and Dongting Lake regions, requiring to focus on vigilance against the rebound of the epidemic. Development of high-sensitivity detection methods and integrating the transmission links such as human and livestock infection, wild animal infection, and O. hupensis into the surveillance-response system will ensure the elimination of schistosomiasis in China by 2030.