Molecular epidemiology and population genetics of Schistosoma mansoni infecting school-aged children situated along the southern shoreline of Lake Malawi, Malawi.

BACKGROUND: In areas of low disease endemicity, highly sensitive diagnostic tools to identify, diagnose, and monitor intestinal schistosomiasis transmission are needed to reliably measure the burden and risk of infection. Here, we used highly sensitive molecular diagnostic methods to investigate Schistosoma mansoni prevalence and transmission along the southern shoreline of Lake Malawi, five years post-disease outbreak. METHODOLOGY AND PRINCIPAL FINDINGS: Faecal and urine samples were provided by school-aged children situated along the southern shoreline of Lake Malawi. Kato-Katz faecal-egg microscopy and point-of-care circulating cathodic antigen (POC-CCA) rapid diagnostic tests were then performed to diagnose infection with S. mansoni. Urine-egg microscopy was also used to diagnose infection with Schistosoma haematobium. In addition, Schistosoma miracidia were isolated from faecal material using a standard miracidium hatching technique. A two-step real-time PCR approach was then used to diagnose infection with S. mansoni using DNA isolated from faecal samples. Furthermore, isolated miracidia were genotyped to species level through PCR and Sanger sequencing. Phylogenetic analyses were then carried out to identify which previously defined S. mansoni cox1 lineage group S. mansoni miracidia were most closely related to. The measured prevalence of S. mansoni infection varied considerably depending on which diagnostic assay was used. When compared to real-time PCR, faecal-egg microscopy had a sensitivity of 9% and a specificity of 100%. When POC-CCA 'trace' results were considered positive, POC-CCA had a sensitivity of 73% and a specificity of 81% when compared to real-time PCR. However, when considered negative, POC-CCA sensitivity was reduced to 56%, whereas specificity was increased to 90%. In addition, a high degree of S. haematobium DNA was detected in DNA isolated from faecal samples and motile S. haematobium miracidia were recovered from faecal samples. Schistosoma mansoni miracidia were closely related to two independent cox1 lineage groups, suggesting multiple recent introduction and colonisation events originating from surrounding east African countries. CONCLUSIONS AND SIGNIFICANCE: Intestinal schistosomiasis is now highly prevalent along the southern shoreline of Lake Malawi just five years post-disease outbreak. In addition, a high prevalence of urogenital schistosomiasis persists. The revision of ongoing schistosomiasis control programmes in this area is therefore recommended. Our study also highlights the need for reliable diagnostic assays capable of distinguishing between Schistosoma species in multispecies co-endemic areas.

Control and elimination of Schistosoma mansoni infection in adult individuals on Ukerewe island, northwestern Tanzania: baseline results before implementation of intervention measures.

BACKGROUND: Communities living along the shoreline and on the islands of Lake Victoria in northwestern Tanzania remain endemic for schistosomiasis and suffer from the life-threatening morbidities associated with the disease. Nevertheless, the control measures particularly the mass drug administration do not cover the adult population. The current project on Ukerewe island aims to close this gap by involving adult community members in the control program. Here we report the baseline results of S. mansoni infection and associated hepatosplenic morbidities and factors before implementing the project activities. METHODS: A cross-sectional analytical study was conducted with 4,043 participants aged ≥ 18 years living in 20 villages on Ukerewe island, northwestern Tanzania. Individual stool and urine samples were collected and examined using the Kato-Katz (KK) technique and point-of-care circulating cathodic antigen testing(POC-CCA) to identify S. mansoni eggs and antigens, respectively. All study participants underwent ultrasound evaluation of S. mansoni hepatosplenic morbidities using the Niamey protocol. Rapid diagnostic tests were used to diagnose HIV infection, hepatitis C and chronic hepatitis B. A questionnaire was used to collect demographic data and reported clinical symptoms of study participants. RESULTS: A total of 4,043 participants took part in the study, of which 49.7% (n = 2,009) and 50.3% (n = 2,035) were male and female, respectively. The overall prevalence of S. mansoni infection was 30.4% (95%CI:29.0-31.9%) and 84.7% (95%CI:83.3-85.9%), respectively, based on the KK technique and the POC-CCA test. The geometrical mean eggs per gram of faeces (GMepg) was 105.3 (95%CI:98.7-112.3% GMepg) with 53.9%, 32.4% and 13.7% of the participants having mild, had moderate and severe intensity of infection. The prevalence of hepatitis C, HIV, and hepatitis B was 0.4%, 2.2% and 4.7%, with 0.2%, 2.2% and 5.4% of the infected individuals coexisting with S. mansoni infection. The prevalence of splenomegaly, periportal fibrosis, hepatomegaly, and portal vein dilatation was 40.5%(95%CI: 38.8-42.1%), 48.1%(95%CI:64.4-49.7%), 66.2%(95%CI:4.6-67.7%) and 67.7%(95%CI:66.2-69.2%), with their prevalence varying depending on the demographic information and infection status of the participants. Other detectable ultrasound-related morbidities included ascites (1.7%), collateral veins (18.3%) and gall bladder wall thickness (40.4%). Age groups, gender, reported clinical characteristics, reported non-use of the drug praziquantel, liver imaging pattern, and place of residence remained independently associated with hepatosplenic morbidities. CONCLUSION: The current study setting is endemic for S. mansoni infection and the population has a high prevalence of the disease associated hepatosplenic morbidities characterized by hepatomegaly, splenomegaly, ascites, gall bladder wall thickening, periportal fibrosis and portal vein dilatation. Several demographic, clinical and epidemiological circumstances remained independently associated with S. mansoni infection and associated morbidities. These findings call for integrative intervention efforts, starting with whole community MDA that includes all out of schools community members.

The effect of intensive praziquantel administration on vaccine-specific responses among schoolchildren in Ugandan schistosomiasis-endemic islands (POPVAC A): an open-label, randomised controlled trial.

BACKGROUND: Vaccine responses differ between populations and are often impaired in rural and low-income settings. The reasons for this are not fully understood, but observational data suggest that the immunomodulating effects of parasitic helminths might contribute. We hypothesised that Schistosoma mansoni infection suppresses responses to unrelated vaccines, and that suppression could be reversed-at least in part-by intensive praziquantel administration. METHODS: We conducted an open-label, randomised controlled trial of intensive versus standard intervention against S mansoni among schoolchildren aged 9-17 years from eight primary schools in Koome islands, Uganda. Children were randomly allocated to either an intensive group or a standard group with a computer-generated 1:1 randomisation using permuted blocks sizes 4, 6, 8, and 10. Participants in the intensive group received three praziquantel doses (approximately 40 mg/kg) 2 weeks apart before first vaccination at week 0, and every 3 months thereafter. Participants in the standard group were given one dose of approximately 40 mg/kg praziquantel after the week 8 primary endpoint. Participants in both groups received the BCG vaccine (Serum Institute of India, Pune, India) at week 0; the yellow fever (Sanofi Pasteur, Lyon, France), oral typhoid (PaxVax, London, UK), and first human papillomavirus (HPV) vaccination (Merck, Rahway, NJ, USA) at week 4; and the HPV booster and tetanus-diphtheria vaccine (Serum Institute of India) at week 28. The primary outcome was vaccine response at week 8 (except for tetanus and diphtheria, which was assessed at week 52). The primary analysis population was participants who were infected with S mansoni at baseline, determined retrospectively using either plasma circulating anodic antigen (CAA) or stool PCR. The safety population comprised all randomly allocated participants. The trial was registered at the ISRCTN Registry (ISRCTN60517191) and is complete. FINDINGS: Between July 9 and Aug 14, 2019, we enrolled 478 participants, with 239 children per group. 276 (58%) participants were male and 202 (42%) participants were female. Among participants who were positive for S mansoni at baseline (171 [72%] in the intensive group and 164 [69%] in the standard group) intensive praziquantel administration significantly reduced pre-vaccination infection intensity (to median 30 CAA pg/mL [IQR 7-223] vs 1317 [243-8562], p<0·001) compared with standard treatment. Intensive praziquantel administration also reduced week 8 HPV-16-specific IgG response (geometric mean ratio 0·71 [95% CI 0·54-0·94], p=0·017), but had no effect on other primary outcomes. Among all participants (regardless of S mansoni status at baseline) intensive praziquantel administration significantly improved week 8 BCG-specific IFNγ ELISpot response (1·20 [1·01-1·43], p=0·038). Recognised adverse effects of praziquantel were reported more frequently in the intensive group. There were no recorded serious adverse events in either group. INTERPRETATION: We show evidence suggesting that praziquantel administration improves the BCG-specific cellular response, but not humoral responses to other vaccines. Despite observational evidence that helminths impair vaccine response, these results show minimal immediate benefits of reducing helminth burden. The effect of longer-term helminth control should be investigated. FUNDING: UK Medical Research Council. TRANSLATION: For the Luganda translation of the abstract see Supplementary Materials section.

Potential associations between Schistosoma mansoni infection and physico-chemical characteristics and water-related human activities in Côte d'Ivoire: a cross-sectional study.

BACKGROUND: Schistosomiasis remains a public health problem, particularly in sub-Saharan Africa. The disease is intimately connected to poverty and environmental factors. Our research was readily embedded into a multi-country schistosomiasis oversampling study. The aim of the study presented here was to determine the prevalence of Schistosoma mansoni and to investigate the role of water body characteristics and water-related human activities in disease transmission. METHODS: In August and September 2022, a cross-sectional study was conducted in the western part of Côte d'Ivoire. Stool and urine samples were collected from 1602 and 1729 children aged 5-14 years, respectively, in 65 villages in the health districts of Biankouma, Ouaninou and Touba. Additionally, data were collected from direct observation of water-related activities at water bodies and interviews conducted with community leaders and health workers. The prevalence and risk factors for Schistosoma infection were assessed using generalised estimating equation models. RESULTS: The prevalence ofS. mansoni and S. haematobium were 27.4% (95% confidence interval [CI] 21.5-34.3%) and 0.1% (95% CI 0.03-0.5%), respectively. Low prevalence of soil-transmitted helminths was observed with 2.4%, 0.4% and 0.2% for hookworm, Trichuris trichiura and Ascaris lumbricoides, respectively. At the health district level, we found S. mansoni prevalence of 34.4% (95% CI 25.0-45.3%), 34.3% (95% CI 24.0-46.2%) and 16.3% (95% CI 9.5-26.6%) for Biankouma, Ouaninou and Touba, respectively. Female and male participants were at a similar risk of infection (29.0% vs. 26.0%, odds ratio [OR]: 1.18, 95% CI 0.92-1.50). Children aged 9-14 years showed a higher prevalence than their younger counterparts aged 5-8 years (34.5% vs. 22.7%, OR: 1.80, 95% CI 1.42-2.27). High infection prevalence was observed in villages where children were washing clothes and dishes at open surface water sites and pursued recreational activities (e.g. swimming and playing in the water). The temperature, total dissolved solids and pH of water samples showed no significant association with S. mansoni infection at the village unit. CONCLUSIONS: Human water-related activities such as washing clothes and playing in the water are risk factors for S. mansoni transmission. Hence, preventive chemotherapy should be combined with information, education and communication to avoid or reduce the frequency of water exposure in children as part of a comprehensive package of interventions towards elimination of schistosomiasis as a public health problem.

Schistosome and malaria exposure and urban-rural differences in vaccine responses in Uganda: a causal mediation analysis using data from three linked randomised controlled trials.

BACKGROUND: Vaccine immunogenicity and effectiveness vary geographically. Chronic immunomodulating parasitic infections including schistosomes and malaria have been hypothesised to be mediators of geographical variations. METHODS: We compared vaccine-specific immune responses between three Ugandan settings (schistosome-endemic rural, malaria-endemic rural, and urban) and did causal mediation analysis to assess the role of Schistosoma mansoni and malaria exposure in observed differences. We used data from the control groups of three linked randomised trials investigating the effects of intensive parasite treatment among schoolchildren. All participants received the BCG vaccine (week 0); yellow fever (YF-17D), oral typhoid (Ty21a), human papillomavirus (HPV; week 4); and HPV booster and tetanus-diphtheria (week 28). Primary outcomes were vaccine responses at week 8 and, for tetanus-diphtheria, week 52. We estimated the total effect (TE) of setting on vaccine responses and natural indirect effect (NIE) mediated through current or previous infection with S mansoni or malaria, and baseline vaccine-specific responses. FINDINGS: We included 239 (43%) participants from the schistosomiasis-endemic setting, 171 (30%) from the malaria-endemic setting, and 151 (27%) from the urban setting. At week 8, vaccine responses were lower in rural settings: schistosomiasis-endemic versus urban settings (TE geometric mean ratio for YF-17D plaque reduction neutralisation at 50% (PRNT50) titres 0·58 [95% CI 0·37 to 0·91], for S Typhi O-lipopolysaccharide-specific IgG 0·61 [0·40 to 0·93], and for tetanus-specific IgG 0·33 [0·22 to 0·51]); malaria-endemic versus urban settings (YF-17D 0·70 [0·49 to 0·99], S Typhi O-lipopolysaccharide-specific IgG 0·29 [0·20 to 0·43], and tetanus-specific IgG 0·53 [-0·35 to 0·80]). However, we found higher BCG-specific IFNγ responses in the malaria-endemic versus urban setting (1·54 [1·20 to 1·98]). The estimated NIEs of setting on vaccine responses mediated through previous and current S mansoni and malaria were not statistically significant. For malaria-endemic versus urban settings, baseline vaccine-specific responses contributed to some but not all differences: S Typhi O-lipopolysaccharide-specific IgG at week 8 (57.9% mediated [38·6 to 77·2]) and week 52 (70·0% mediated [49·4 to 90·6]) and BCG at week 52 (46.4% mediated [-4·8 to 97·7]). INTERPRETATION: We found significant variation in vaccine response between urban and rural settings but could not confirm a causal role for schistosome or malaria exposure. Other exposures require consideration. FUNDING: UK Medical Research Council.

Intermediate and definitive hosts of wild Schistosoma mansoni: ecological niche modeling of hosts in low endemicity areas.

The relationship between the environment and animal life began to be seen as an important tool to help control zoonoses. Climate variations lead to changes in the environment, which can influence the spatial distribution of species and, consequently, the spread of diseases to humans. Considered the main non-human definitive host species of Schistosoma mansoni in Brazil, the wild rodent Nectomys squamipes plays an important role as a reservoir in maintaining the schistosomiasis cycle in the absence of humans. This study demonstrates the results of ecological niche modeling of intermediate and definitive wild hosts of S. mansoni in the Regional Health Superintendence of Barbacena (Minas Gerais State), which has registered 31 municipalities, 80% of which are classified as endemic for parasitosis. Environmental variables associated with the distribution of each species were used based on information from the scientific collections of Global Biodiversity Information Facility (GBIF) and Species Link to project the ecological niche model in the geographic space. Abiotic variables such as the mean annual temperature, isothermality, and precipitation seasonality were obtained from World Clim. Ecological niche modeling of the wild host, N. squamipes, revealed the occurrence of the species in geographic overlap with the Biomphalaria species. Knowing the influence of bioclimatic variables and identifying favorable conditions for the establishment, occurrence, and distribution of species are important information for developing strategic actions for the surveillance and control of this endemic species. The presence of the definitive wild host needs to be considered by control programs of schistosomiasis.

Pre-vaccination Schistosoma mansoni and hookworm infections are associated with altered vaccine immune responses: a longitudinal analysis among adolescents living in helminth-endemic islands of Lake Victoria, Uganda.

Background: Variations in vaccine responses have been observed between populations. A role for helminth infections has been proposed due to their immunomodulatory properties. In a secondary analysis of data from a randomised trial assessing effects of anthelminthic treatment on vaccine responses, we examined associations between helminth infections at baseline prior to vaccine administration, and vaccine responses among adolescents (9-17 years) in Koome Islands, Lake Victoria, Uganda. Methods: Participants received BCG [week 0], yellow fever (YF-17D), oral typhoid (Ty21a), HPV-prime [week 4], and HPV-boost, tetanus/diphtheria [week 28]. Outcomes were BCG-specific interferon-γ ELISpot responses and antibody responses to yellow-fever-, typhoid-, HPV-, tetanus- and diphtheria-specific antigens measured at two time points post vaccination. S. mansoni infection was determined as positive if either the plasma Circulating Anodic Antigen (CAA) assay or stool PCR were positive. Hookworm and Strongyloides were determined by stool PCR. Linear mixed effects regression was used to assess associations. Results: Among 478 adolescents, 70% were Schistosoma mansoni (Sm) infected and 23% hookworm infected at baseline. Sm was associated with lower Salmonella Typhi O:LPS-specific IgG responses (adjusted geometric mean ratio (aGMR) 0.69 (0.57-0.83)), and hookworm with higher diphtheria-specific IgG (aGMR 1.16 (1.02, 1.31)) and lower HPV-16-specific IgG (aGMR 0.70 (0.55, 0.90)) post-vaccination. High Sm intensity was associated with lower BCG-specific interferon-γ and S. Typhi O:LPS-specific IgG. Conclusions: We found inverse associations between Sm and responses to two live vaccines, whereas hookworm was positively associated with diphtheria-specific IgG. These findings support the hypothesis that helminth infections can modulate vaccine responses, while also highlighting potential heterogeneity in the direction of these effects.

Prevalence of human schistosomiasis in various regions of Tanzania Mainland and Zanzibar: A systematic review and meta-analysis of studies conducted for the past ten years (2013-2023).

Schistosomiasis is a significant public health problem in Tanzania, particularly for the people living in the marginalized settings. We have conducted a systematic review with meta-analysis on the prevalence of schistosomiasis to add knowledge towards the development of effective approaches to control the disease in Tanzania. Online databases namely, Pub Med, SCOPUS and AJOL, were systematically searched and a random effect model was used to calculate the pooled prevalence of the disease. Heterogeneity and the between studies variances were determined using Cochran (Q) and Higgins (I2) tests, respectively. A total of 55 articles met the inclusion criterion for this review and all have satisfactory quality scores. The pooled prevalence of the disease in Tanzania was 26.40%. Tanzania mainland had the highest schistosomiasis prevalence (28.89%) than Zanzibar (8.95%). Sub-group analyses based on the year of publication revealed the going up of the pooled prevalence, whereby for (2013-2018) and (2018-2023) the prevalence was 23.41% and 30.06%, respectively. The prevalence of the Schistosoma mansoni and Schistosoma hematobium were 37.91% and 8.86% respectively. Mara, Simuyu, and Mwanza were the most prevalent regions, with a pooled prevalence of 77.39%, 72.26%, and 51.19%, respectively. The pooled prevalence based on the diagnostic method was 64.11% for PCR and 56.46% for POC-CCA, which is relatively high compared to other tests. Cochrans and Higgins (I2) test has shown significant heterogeneity (p-value = 0.001 and I2 = 99.6). Factors including age, region, diagnostic method and sample size have shown significant contribution to the displayed heterogeneity. The pronounced and increasing prevalence of the disease suggests potential low coverage and possibly lack of involvement of some regions in the control of the disease. This, therefore, calls for an intensive implementation of control interventions in all endemic regions, preferably using an integrated approach that targets several stages of the disease lifecycle.

Prevalence and correlations of schistosomiasis mansoni and schistosomiasis haematobium among humans and intermediate snail hosts: a systematic review and meta-analysis.

BACKGROUND: The control of schistosomiasis is particularly difficult in sub-Saharan Africa, which currently harbours 95% of this disease. The target population for preventive chemotherapy (PC) is expanded to all age group at risk of infection, thus increasing the demands of praziquantel (PZQ) tablets according to the new released guideline by World Health Organization. Due to the gap between available PZQ for PC and requirements, alternative approaches to assess endemicity of schistosomiasis in a community, are urgently needed for more quick and precise methods. We aimed to find out to which degree the infection status of snails can be used to guide chemotherapy against schistosomiasis. METHODS: We searched literature published from January 1991 to December 2022, that reported on the prevalence rates of Schistosoma mansoni, S. haematobium in the intermediate snails Biomphalaria spp. and Bulinus spp., respectively, and in humans. A random effect model for meta-analyses was used to calculate the pooled prevalence estimate (PPE), with heterogeneity assessed using I-squared statistic (I2), with correlation and regression analysis for the exploration of the relationship between human S. mansoni and S. haematobium infections and that in their specific intermediate hosts. RESULTS: Forty-seven publications comprising 59 field investigations were included. The pooled PPE of schistosomiasis, schistosomiasis mansoni and schistosomiasis haematobium in humans were 27.5% [95% confidence interval (CI): 24.0-31.1%], 25.6% (95% CI: 19.9-31.3%), and 28.8% (95% CI: 23.4-34.3%), respectively. The snails showed an overall infection rate of 8.6% (95% CI: 7.7-9.4%), with 12.1% (95% CI: 9.9-14.2%) in the Biomphalaria spp. snails and 6.9% (95% CI: 5.7-8.1%) in the Bulinus spp. snails. The correlation coefficient was 0.3 (95% CI: 0.01-0.5%, P < 0.05) indicating that the two variables, i.e. all intermediate host snails on the one hand and the human host on the other, were positively correlated. CONCLUSIONS: The prevalence rate of S. mansoni and S. haematobium is still high in endemic areas. Given the significant, positive correlation between the prevalence of schistosomes in humans and the intermediate snail hosts, more attention should be paid to programme integration of snail surveillance in future.

[Schistosomiasis in areas of low endemicity: an overly neglected disease. The example of Schistosoma monsoni in BrazilEsquistossomose em áreas de baixa endemicidade, uma doença muito negligenciada. O exemplo de Schistosoma mansoni no Brasil]. / La schistosomose dans les zones de faible endémicité, une maladie trop négligée. Le cas de Schistosoma monsoni au Brésil.

Human schistosomiasis is a parasitic disease caused by an infection with trematodes of the genus Schistosoma. The disease mainly affects impoverished populations. Around 800 million people are exposed to the infection, which is a public health problem in the tropical and subtropical regions of Africa, Asia, the Caribbean and South America. In Brazil, Schistosoma mansoni is the only species that causes schistosomiasis and the disease is widely distributed. Conventional diagnosis of the disease is carried out by detecting eggs using parasitological methods, such as the Kato-Katz test. Schistosomiasis has been reported in all regions of Brazil and is characterized as endemic in seven states in the Northeast Region and two states in the Southeast Region. In 2015, 78,7% of all cases reported in Brazil occurred in the Northeast Region. It is estimated that 1,5 million people is infected with this disease in Brazil and more than 25 millions live in areas with a high risk of transmission. Despite the reduction in mortality and morbidity, schistosomiasis was responsible for 8,756 deaths between 2000 and 2011 and 2,517 deaths between 2015 and 2019 in Brazil and it remains an important public health problem. In the state of Rio de Janeiro, some areas have low endemicity or isolated foci of Schistosoma mansoni and the majority of infected individuals have mild infections. The last survey of the disease in the state of Rio de Janeiro was carried out between 2010 and 2015 in students aged 7 to 17.Schistosomiasis was reported in 10 of the 21 municipalities studied. Of the 5,111 school children screened for S. mansoni infection, 46 (1,65%) were tested positive. Studies carried out in areas of low endemicity in Rio de Janeiro showed that among the 205 patients infected by S. mansoni in Sumidouro, around 84% were aged 14 or over and all, except one individual, had the intestinal form (91,2%) or hepato-intestinal (8,3%) of schistosomiasis. Another study carried out in Sumidouro showed that with tests based on patent Schistosoma egg infection determined by the Kato-Katz test, active infections were diagnosed in eight (8/108) individuals. The intensity of infection expressed by parasite loads ranged from 6 to 72 eggs per gram of feces/individual. The results showed DNA amplification in 32 of the 100 individuals tested by real-time PCR. All individuals with patent ovo infection showed positive DNA amplification. These studies showed that if we only analyzed school-age children using the Kato-Katz test, the majority of the infected population would never be diagnosed with S. mansoni infection. In situations of low endemicity, with low intensities of infection, with low severity in the population and in the most affected age groups, schistosomiasis requires a more sensitive diagnostic approach (e.g. screening by PCR rather than Kato test), otherwise many infected individuals will remain invisible to the healthcare system.

A esquistossomose humana é uma doença parasitária causada por uma infecçâo por vermes sanguíneos do gènero Schistosoma. A doença afeta principalmente populaçoes empobrecidas. Cerca de 800 milhoes de pessoas estâo expostas à infecçâo, sendo um problema de saúde pública nas regioes tropicais e subtropicais de África, Ásia, Caribe e América do Sul. No Brasil, o Schistosoma mansoni é a única espécie causadora da esquistossomose e a doença é amplamente distribuida. O diagnóstico convencional da doença é realizado pela detecçâo dos ovos através de métodos parasitológicos, como o teste de Kato-Katz. A esquistossomose foi notificada em todas as regioes do Brasil, e é caracterizada como endèmica em sete estados da Regiâo Nordeste e dois estados da Regiâo Sudeste. Em 2015, 78,7% de todos os casos notificados no Brasil ocorreram na Regiâo Nordeste. Estima-se que 1,5 milhâo de pessoas estejam infectadas com esta doença no Brasil e mais de 25 milhoes vivam em áreas com alto risco de transmissâo. Apesar da reduçâo da mortalidade e morbidade, a esquistossomose foi relatada em 8.756 mortes entre 2000 e 2011 e em 2.517 mortes entre 2015 e 2019 no Brasil e continua sendo um importante problema de saúde pública. No Estado do Rio de Janeiro, algumas áreas apresentam baixa endemicidade ou focos isolados de Schistosoma mansoni e a maioria dos individuos infectados apresenta infecçoes leves. O último levantamento da doença no Estado do Rio de Janeiro foi realizado entre 2010 e 2015 em estudantes de 7 a 17 anos. A esquistossomose foi relatada em 10 dos 21 municipios estudados. Das 5.111 crianças escolares triadas para infecçâo por S. mansoni, 46 (1,65%) testaram positivo. Estudos realizados em áreas de baixa endemicidade no Rio de Janeiro mostraram que dentre os 205 pacientes infectados por S. mansoni em Sumidouro, cerca de 84% tinham 14 anos ou mais e todos, exceto um individuo, tinham a forma intestinal (91,2%) ou hepato-intestinal (8,3%) da esquistossomose. Outro estudo realizado em Sumidouro, mostrou que testes baseados em infecçâo patente de ovo de Schistosoma determinada pelo teste de Kato-Katz, infecçoes ativas foram diagnosticadas em oito (8/108) individuos. A intensidade de infecçâo expressa pelas cargas parasitárias variou de 6 a 72 ovos por grama de fezes/individuo. Os resultados mostraram amplificaçâo do DNA em 32 dos 100 individuos testados por PCR em tempo real. Todos os indivíduos com infecçâo ovo-patente apresentaram amplificaçâo de DNA positiva. Tais estudos mostraram que se analisarmos apenas crianças em idade escolar pelo teste de Kato-Katz, a maioria da populaçâo infectada nunca seria diagnosticada com infecçâo pelo S. mansoni. Em situaçoes de baixa endemicidade, com baixas intensidades de infecçâo, com baixa gravidade na populaçâo e nas faixas etárias mais afetadas, a esquistossomose requer uma abordagem diagnóstica mais sensivel (por exemplo, triagem por PCR em vez do teste de Kato), caso contràrio, muitos individuos infectados permanecerâo invisiveis para o sistema de saúde.

Prevalence and associated factors of schistosomiasis among pregnant women in northern Senegal.

BACKGROUND: Schistosomiasis remains a public health concern worldwide. It is responsible for more than 240 million cases in 78 countries, 40 million of whom are women of childbearing age. In the Senegal River basin, both Schistosoma haematobium and Schistosoma mansoni are very prevalent in school-age children. However, there is a lack of information on the burden of schistosomiasis in pregnant women, which can cause complications in the pregnancy outcome. This study aimed to determine the prevalence and associated factors of schistosomiasis in pregnant women. METHODS: We conducted a prospective cross-sectional study of pregnant women attending antenatal clinics at the health center of the Senegalese Sugar Company and at the hospital of Richard Toll between August and December 2021. The urine and stool samples collected were examined using microscopy techniques and quantitative polymerase chain reaction (qPCR) to detect the presence of S. haematobium and S. mansoni. The urines were previously tested using urine reagent strips to detect hematuria and proteinuria. Socio-demographical, clinical, and diagnostically data were recorded by the midwife and the gynaecologist. The data were analyzed using a logistic regression model. RESULTS: Among the 298 women examined for the infection by microscopic, 65 (21.81%) were infected with urogenital schistosomiasis, 10 (3.36%) with intestinal schistosomiasis, and 4 (1.34%) were co-infected with both types of schistosomiasis. Out of the 288 samples tested by qPCR, 146 (48.99%) were positive for S. haematobium, 49 (35.51%) for S. mansoni and 22 (15.94%) for both species (co-infection). Pregnant women having microscopic haematuria and proteinuria were significantly more infected (p < 0.05). CONCLUSION: This study has revealed a high prevalence of schistosomiasis in pregnant women in Senegal. The qPCR allowed us to detect more cases compared to the microscopy. There is a need to conduct more studies to understand the real burden of the disease and to set up a surveillance system to prevent pregnancy-related complications.

Factors associated with hookworm and Schistosoma mansoni infections among school-aged children in Mayuge district, Uganda.

BACKGROUND: Hookworm infection and schistosomiasis are two of sub-Saharan Africa's most common neglected tropical diseases. An annual mass drug administration (MDA) program against schistosomiasis and soil-transmitted helminths (STHs), including hookworm, has been implemented in Mayuge district, Uganda, since 2003 to date. However, hookworm and schistosomiasis remain prevalent in Mayuge district. Understanding the factors that predispose children to these infections in the context of MDA could inform interventions to reduce prevalence in Uganda and similar settings. METHOD: This cross-sectional study took place in 33 randomly selected primary schools in the Mayuge district from January to February 2022. Children in primary classes 4 or 5, in the selected schools provided single stool samples and completed questionnaires. Stool specimens were examined using the Kato-Katz method to determine the prevalence of hookworm and schistosomiasis. We performed univariable and multivariable logistic regression to assess the associations of each infection with potential risk factors. RESULT: A total of 1,617 students (mean age 12.1 years, 50.1% male) were enrolled. The prevalence of hookworm infection and schistosomiasis was 21.8% (95% confidence interval (CI): 19.8-23.9%) and 18.7% (95% CI: 16.8-20.7%), respectively. In multivariable analysis, longer water fetching time (over 30 min versus less than 30 min) and working daily in the soil were associated with increased odds of hookworm infection (adjusted odds ratio (AOR): 1.49, 95% CI: 1.13-1.96 and 1.37, 95% CI: 1.03-1.82, respectively). Higher odds of schistosomiasis were linked to proximity to water bodies within a one-hour walking distance (AOR: 1.84, 95% CI: 1.35-2.50), and not always washing hands before eating (AOR: 2.00, 95% CI: 1.50-2.67). Swimming, bathing, or washing in water bodies twice a week, compared to never, also increased schistosomiasis odds (AOR: 2.91, 95% CI: 1.66-5.13). CONCLUSION: Consistent with the mechanisms of acquisition, hookworm infection increased with exposure to soil, and schistosomiasis increased with exposure to unclean water. Our findings highlight the importance of Water, Sanitation, and Hygiene programs and strategies aimed at reducing exposure within the framework of Neglected Tropical Disease elimination programs.

Prevalence and factors associated with Schistosoma mansoni infection among primary school children in Kersa District, Eastern Ethiopia.

Background: Schistosomiasis is a neglected tropical disease and an important parasite negatively impacting socio-economic factors. Ethiopia's Federal Ministry of Health targeted the elimination of schistosomiasis infection in school-aged children by 2020. However, Schistosoma mansoni still affects approximately 12.3 million school-aged children in Ethiopia. Although the study was conducted in some regions of the country, previous studies were conducted on urban school children and were limited to the burden of infection. Overall, there is a lack of information about schistosomiasis in eastern Ethiopia, particularly among school children. Therefore, this study aimed to assess the prevalence and factors associated with Schistosoma mansoni infection among primary school children in Kersa district, Eastern Ethiopia. Methods: A cross-sectional study was conducted among 419 school children using systematic random sampling from April 10 to May 09, 2019. The stool samples were collected and examined using the Keto-Katz method. A structured and pretested questionnaire was used to collect data from participants. Data were entered using Epi-Data version 3.1 and analysed using SPSS version 24. A bivariable and multivariable logistic regression analyses were used to identify factors associated with Schistosoma mansoni infection. P-value < 0.05 and adjusted odds ratio (AOR) (95% confidence interval (CI)) were used to identify statistically significant associations. Results: This study's overall prevalence of S. mansoni was 19.4% (95% CI [16-23]). Absence of the latrines in household (AOR = 2.35, 95% CI [1.25-4.38]), swimming in the river (AOR = 2.82, 95% CI [1.33-5.88]), unprotected water sources (AOR = 3.5, 95% CI [1.72-7.10]), irregular shoe wearing habits (AOR = 2.81, 95% CI [1.51-5.23]), and water contact during cross of river (AOR = 2.192; 95% CI [1.113-4.318]) were factors independently associated with S. mansoni infection. Conclusion: Schistosoma mansoni infection remains a public health problem in the study area. Using a latrine in each household, using protected water, wearing shoes regularly, and reducing water contact were necessary to control Schistosoma mansoni infection.

Schistosoma mansoni infection in residents of a riverside community in Eastern Amazon.

Schistosoma mansoni worms cause a waterborne parasitic disease called schistosomiasis. It commonly affects individuals in lack of sanitation structure. In Brazil, Pará state has Belém as one of the worst sanitation-ranking places in 2023, where schistosomiasis transmission was already documented. This study reports the occurrence of schistosomiasis in residents of Ilha das Onças, an island next to Belém. Stool samples were obtained from participants over 2 years old, all residents from Furo do Rio Grande, one of the rivers on the island. The Kato-Katz technique was performed for parasite investigation in the stool samples. Each participant responded to a sociodemographic and clinical questionnaire. The residences were georeferenced for map designing. Three out of 263 participants were S. mansoni positive, all men, ages ranging from 19 to 41 years old, with low parasitic load. Malacological surveys were carried out, but no Biomphalaria snails were found. Risk factors for schistosomiasis establishment are present on the island, and the lack of sanitation makes it a potential risk area. Malacological surveys are highly encouraged as preventive measures, as well as health surveillance for riverside populations, generating data that will help health authorities in the management and planning of preventive control actions.

The short-term impact of Schistosoma mansoni infection on health-related quality of life: implications for current elimination policies.

The WHO aims to eliminate schistosomiasis as a public health problem by 2030. However, standard morbidity measures poorly correlate to infection intensities, hindering disease monitoring and evaluation. This is exacerbated by insufficient evidence on Schistosoma's impact on health-related quality of life (HRQoL). We conducted community-based cross-sectional surveys and parasitological examinations in moderate-to-high Schistosoma mansoni endemic communities in Uganda. We calculated parasitic infections and used EQ-5D instruments to estimate and compare HRQoL utilities in these populations. We further employed Tobit/linear regression models to predict HRQoL determinants. Two-thirds of the 560 participants were diagnosed with parasitic infection(s), 49% having S. mansoni. No significant negative association was observed between HRQoL and S. mansoni infection status/intensity. However, severity of pain urinating (ß = -0.106; s.e. = 0.043) and body swelling (ß = -0.326; s.e. = 0.005), increasing age (ß = -0.016; s.e. = 0.033), reduced socio-economic status (ß = 0.128; s.e. = 0.032), and being unemployed predicted lower HRQoL. Symptom severity and socio-economic status were better predictors of short-term HRQoL than current S. mansoni infection status/intensity. This is key to disentangling the link between infection(s) and short-term health outcomes, and highlights the complexity of correlating current infection(s) with long-term morbidity. Further evidence is needed on long-term schistosomiasis-associated HRQoL, health and economic outcomes to inform the case for upfront investments in schistosomiasis interventions.

Re-assessment of schistosomiasis in nine endemic districts with cluster sampling in Sierra Leone.

Background: Baseline mapping showed that schistosomiasis was highly/moderately endemic in nine districts in Sierra Leone. Mass drug administration (MDA) with praziquantel started in 2009, and after multiple rounds of treatment, an impact assessment was conducted in 2016 followed by a second re-assessment in 2022 using cluster sampling to provide more granular data for refining chiefdom (sub-district) treatment strategies. Methods: On average, 20 rural villages were systematically selected per district by probability proportional to population size across the nine districts. Surveys were conducted in schools, and 24 school children aged between 5 and 14 years were randomly selected, with an equal number of boys and girls. One stool sample and one urine sample were collected per child. Two Kato-Katz slides were examined per stool for Schistosoma mansoni infection. Hemastix strips were used as a proxy for S. haematobium infection with urine filtration used for egg counts on hematuria-positive samples. Results: In total, 4,736 stool samples and 4,618 urine samples were examined across 200 schools in 125 chiefdoms. Overall, the prevalence of S. mansoni was 16.3% (95% CI: 15.3-17.4%), while the overall prevalence of S. haematobium was 2.0% (95% CI: 1.6-2.4%) by hematuria. The prevalence of heavy infections for S. mansoni and S. haematobium was 1.5% (95% CI: 1.1-1.9%) and 0.02% (95% CI: 0.0-0.14%), respectively. Among 125 chiefdoms surveyed, the overall schistosomiasis prevalence was <10% in 65 chiefdoms, 10-49.9% in 47 chiefdoms, and ≥ 50% in 13 chiefdoms. There was a mixed relationship between schistosomiasis in school children and WASH access in schools. Conclusion: Sierra Leone has made significant progress in reducing schistosomiasis prevalence across the country after a decade of MDA intervention. However, high prevalence remains in some hotspot chiefdoms. The next steps are for the national program to investigate and address any potential issues such as low coverage or poor knowledge of schistosomiasis risk behaviors and, where appropriate, consider broadening to community-wide treatment in hotspot chiefdoms or communities.

Rapid appraisal of liver diseases using transient elastography, abdominal ultrasound, and microbiology in Côte d'Ivoire: A single-center study.

BACKGROUND: Liver diseases of infectious and non-infectious etiology cause considerable morbidity and mortality, particularly in low- and middle-income countries (LMICs). However, data on the prevalence of liver diseases and underlying risk factors in LMICs are scarce. The objective of this study was to elucidate the occurrence of infectious diseases among individuals with chronic liver damage in a rural setting of Côte d'Ivoire. METHODOLOGY: In 2021, we screened 696 individuals from four villages in the southern part of Côte d'Ivoire for hepatic fibrosis and steatosis, employing transient elastography (TE) and controlled attenuation parameter (CAP). We classified CAP ≥248 dB/m as steatosis, TE ≥7.2 kPa as fibrosis, and did subgroup analysis for participants with TE ranging from 7.2 kPa to 9.1 kPa. Clinical and microbiologic characteristics were compared to an age- and sex-matched control group (TE <6.0 kPa; n = 109). Stool samples were subjected to duplicate Kato-Katz thick smears for diagnosis of Schistosoma mansoni. Venous blood samples were examined for hepatitis B and hepatitis C virus. Additionally, an abdominal ultrasound examination was performed. PRINCIPAL FINDINGS: Among 684 individuals with valid TE measurements, TE screening identified hepatic pathologies in 149 participants (17% with fibrosis and 6% with steatosis). 419 participants were included for further analyses, of which 261 had complete microbiologic analyses available. The prevalence of S. mansoni, hepatitis B, and hepatitis C were 30%, 14%, and 7%, respectively. Logistic regression analysis revealed higher odds for having TE results between 7.2 kPa and 9.1 kPa in individuals with S. mansoni infection (odds ratio [OR] = 3.02, 95% confidence interval [CI] = 1.58-5.76, P = 0.001), while HCV infection (OR = 5.02, 95% CI = 1.72-14.69, P = 0.003) and steatosis (OR = 4.62, 95% CI = 1.60-13.35, P = 0.005) were found to be risk factors for TE ≥9.2 kPa. CONCLUSIONS/SIGNIFICANCE: Besides viral hepatitis, S. mansoni also warrants consideration as a pathogen causing liver fibrosis in Côte d'Ivoire. In-depth diagnostic work-up among individuals with abnormal TE findings might be a cost-effective public health strategy.

Re-assessing thermal response of schistosomiasis transmission risk: Evidence for a higher thermal optimum than previously predicted.

The geographical range of schistosomiasis is affected by the ecology of schistosome parasites and their obligate host snails, including their response to temperature. Previous models predicted schistosomiasis' thermal optimum at 21.7°C, which is not compatible with the temperature in sub-Saharan Africa (SSA) regions where schistosomiasis is hyperendemic. We performed an extensive literature search for empirical data on the effect of temperature on physiological and epidemiological parameters regulating the free-living stages of S. mansoni and S. haematobium and their obligate host snails, i.e., Biomphalaria spp. and Bulinus spp., respectively. We derived nonlinear thermal responses fitted on these data to parameterize a mechanistic, process-based model of schistosomiasis. We then re-cast the basic reproduction number and the prevalence of schistosome infection as functions of temperature. We found that the thermal optima for transmission of S. mansoni and S. haematobium range between 23.1-27.3°C and 23.6-27.9°C (95% CI) respectively. We also found that the thermal optimum shifts toward higher temperatures as the human water contact rate increases with temperature. Our findings align with an extensive dataset of schistosomiasis prevalence in SSA. The refined nonlinear thermal-response model developed here suggests a more suitable current climate and a greater risk of increased transmission with future warming for more than half of the schistosomiasis suitable regions with mean annual temperature below the thermal optimum.

Rapid and Comprehensive Screening for Urogenital and Gastrointestinal Schistosomiasis with Handheld Digital Microscopy Combined with Circulating Cathodic Antigen Testing.

Novel methods are required to aid the monitoring of schistosomiasis control and elimination initiatives through mass drug administration. Portable digital and mobile phone microscopy is a promising tool for this purpose. This cross-sectional study evaluated the diagnostic operating characteristics of a converted mobile phone microscope (the SchistoScope) for the detection of Schistosoma haematobium eggs, as determined by community-based field workers and expert microscopists, compared with a field gold standard of light microscopy. Three hundred sixty-five urine samples were evaluated by conventional light microscopy, with 49 (13.4%) positive for S. haematobium. Compared with light microscopy, the sensitivity and specificity of S. haematobium detection by field microscopists trained to use the SchistoScope were 26.5% (95% CI: 14.9-41.1%) and 98.4% (95% CI: 96.3-99.5%), respectively. The sensitivity and specificity of S. haematobium detection by expert microscopists using the SchistoScope was 74% (95% CI: 59.7-85.4%) and 98.1% (95% CI: 95.9-99.3%), respectively, compared with light microscopy. The sensitivity rose to 96.1% and 100% when evaluating for egg counts greater than five and 10 eggs per 10 mL, respectively. A point-of-care circulating cathodic anion (POC CCA) test was used to evaluate Schistosoma mansoni; however, there were too few positive samples to reliably comment on diagnostic characteristics. This study demonstrated that a "urine-only" approach to rapidly screen for schistosomiasis at the point of sample collection can be conducted with mobile phone microscopy (S. haematobium) coupled with POC CCA (S. mansoni). Such an approach may aid in streamlined schistosomiasis control and elimination initiatives.

Climate and urbanization drive changes in the habitat suitability of Schistosoma mansoni competent snails in Brazil.

Schistosomiasis is a neglected tropical disease caused by Schistosoma parasites. Schistosoma are obligate parasites of freshwater Biomphalaria and Bulinus snails, thus controlling snail populations is critical to reducing transmission risk. As snails are sensitive to environmental conditions, we expect their distribution is significantly impacted by global change. Here, we used machine learning, remote sensing, and 30 years of snail occurrence records to map the historical and current distribution of forward-transmitting Biomphalaria hosts throughout Brazil. We identified key features influencing the distribution of suitable habitat and determined how Biomphalaria habitat has changed with climate and urbanization over the last three decades. Our models show that climate change has driven broad shifts in snail host range, whereas expansion of urban and peri-urban areas has driven localized increases in habitat suitability. Elucidating change in Biomphalaria distribution-while accounting for non-linearities that are difficult to detect from local case studies-can help inform schistosomiasis control strategies.