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Schistosomiasis is a tropical disease transmitted in an aqueous environment by cercariae from the Schistosoma genus. This disease affects 200 million people living in risk areas around the world. The control of schistosomiasis is realized by chemotherapy, wastewater sanitation, health education, and mollusk control using molluscicidal agents. This work evaluates the effects of a nanoemulsion containing essential oil from Myrciaria floribunda leaves as a molluscicidal and cercaricidal agent against Biomphalaria glabrata mollusks and Schistosoma mansoni cercariae. The Myrciaria floribunda essential oil from leaves showed nerolidol, β-selinene, 1,8 cineol, and zonarene as major constituents. The formulation study suggested the F3 formulation as the most promising nanoemulsion with polysorbate 20 and sorbitan monooleate 80 (4:1) with 5% (w/w) essential oil as it showed a smaller droplet size of approximately 100 nm with a PDI lower than 0.3 and prominent bluish reflection. Furthermore, this nanoemulsion showed stability after 200 days under refrigeration. The Myrciaria floribunda nanoemulsion showed LC50 values of 48.11 µg/mL, 29.66 µg/mL, and 47.02 µg/mL in Biomphalaria glabrata embryos, juveniles, and adult mollusks, respectively, after 48 h and 83.88 µg/mL for Schistosoma mansoni cercariae after 2 h. In addition, a survival of 80% was observed in Danio rerio, and the in silico toxicity assay showed lower overall human toxicity potential to the major compounds in the essential oil compared to the reference molluscicide niclosamide. These results suggest that the nanoemulsion of Myrciaria floribunda leaves may be a promising alternative for schistosomiasis control. [ABSTRACT FROM AUTHOR]

Schistosomiasis is a tropical disease transmitted in an aqueous environment by cercariae from the Schistosoma genus. This disease affects 200 million people living in risk areas around the world. The control of schistosomiasis is realized by chemotherapy, wastewater sanitation, health education, and mollusk control using molluscicidal agents. This work evaluates the effects of a nanoemulsion containing essential oil from Myrciaria floribunda leaves as a molluscicidal and cercaricidal agent against Biomphalaria glabrata mollusks and Schistosoma mansoni cercariae. The Myrciaria floribunda essential oil from leaves showed nerolidol, β-selinene, 1,8 cineol, and zonarene as major constituents. The formulation study suggested the F3 formulation as the most promising nanoemulsion with polysorbate 20 and sorbitan monooleate 80 (4:1) with 5% (w/w) essential oil as it showed a smaller droplet size of approximately 100 nm with a PDI lower than 0.3 and prominent bluish reflection. Furthermore, this nanoemulsion showed stability after 200 days under refrigeration. The Myrciaria floribunda nanoemulsion showed LC50 values of 48.11 µg/mL, 29.66 µg/mL, and 47.02 µg/mL in Biomphalaria glabrata embryos, juveniles, and adult mollusks, respectively, after 48 h and 83.88 µg/mL for Schistosoma mansoni cercariae after 2 h. In addition, a survival of 80% was observed in Danio rerio, and the in silico toxicity assay showed lower overall human toxicity potential to the major compounds in the essential oil compared to the reference molluscicide niclosamide. These results suggest that the nanoemulsion of Myrciaria floribunda leaves may be a promising alternative for schistosomiasis control.

This paper summarizes the factors affecting schistosomiasis transmission in the middle and lower reaches of the Yangtze River before and after the completion of the Three Gorges Dam and analyzes schistosomiasis prevalence trends to provide a basis for the application of the Three Gorges project methodologies in other areas. The Three Gorges Dam has demonstrated a positive effect on schistosomiasis control. Hubei, Hunan, Jiangxi, Anhui, and Jiangsu in the middle and lower reaches of the Yangtze River are currently regions with a high prevalence of schistosomiasis. These five provinces contained 97.62% of known snail areas and 93.66% of calculated schistosomiasis cases with 90.07% of counties (cities, districts) not yet meeting the criteria for schistosomiasis transmission interruption by the end of 2016. After the Three Gorges Dam was built, the prevalence of schistosomiasis in the middle and lower reaches of the Yangtze River decreased. By the end of 2016, the estimated number of cases decreased by 92.75% and the snail habitat areas decreased by 6.56% compared to 2004. No acute schistosomiasis cases have occurred for two consecutive years since 2015.

Abstract Plant-derived molluscicides have been indicated as biodegradable and low-cost strategies for control of Biomphalaria spp., intermediate host for the Schistosoma. This study evaluated whether the crude ethanolic extract of the Persea americana stem bark has molluscicidal activity against embryos, newly-hatched and adults of Biomphalaria glabrata. The extract was obtained, characterized and its toxicity analyzed by snail embryotoxicity test (144 h) and acute toxicity test with newly-hatching and adult snails (96 h). Results showed the presence of flavonoids, anthraquinone heterosides, coumarins and tannins in the crude ethanolic extract, which showed molluscicidal activity against all life cycle stages of B. glabrata. The LC50 for embryos, newly-hatched and adults were 27.06, 30.60 and 55.55 ppm, respectively. Embryos exposed to the extract at 50 ppm showed hatching inhibition and at 6.2 and 25 ppm had the highest rates of morphological alterations, such as shell malformations and coagulation of the perivitelline substance. Adult snails exposed to the extract at 75 ppm showed a peak of behavioral changes, such as lethargy and shell reclusion, in addition to answers like hemolymph release in most concentrations. Further studies are required, prioritizing toxicity testing on non-target organisms and further elucidation of the active molecules.

Abstract Background Schistosomiasis remains a public health problem in many regions of the world, including Nigeria. Current control strategy involves mass drug administration with praziquantel to the endemic population. To complement and sustain on-going preventive chemotherapy, we developed a health educational game named Schisto and Ladders™ and tested its potential for the control of schistosomiasis among schoolchildren living in Imala-Odo, a highly endemic community near Abeokuta, Nigeria. Methods One hundred school children were randomly selected and divided into intervention and control groups through balloting. Their knowledge, attitudes and practices (KAP) concerning schistosomiasis transmission, control and prevention were assessed using structured questionnaires. Schisto and Ladders™ game were given to the intervention group and the popular Snake and Ladders™ game to the control group. Both games were played for 2 months under the supervision of their class teachers. A post-KAP assessment was carried out in both groups, including focus group discussions (FGDs) to investigate knowledge and the impact of the games. Results Knowledge about urinary schistosomiasis and its transmission significantly improved (P = 0.000) in the intervention group (68.0%) compared to the control group (8.0%). FGDs showed that the frequency of visits to dam water also significantly reduced (P = 0.048) in the intervention group (18.0%) compared to the control group (40.0%). There was a significant increase in knowledge regarding risk behaviours, prevention and control of schistosomiasis among the intervention group, but no new knowledge gained in the control group. Conclusions This study demonstrates the potential of the health education game Schisto and Ladders™ for teaching basic health education and promoting behavioural changes among schoolchildren in endemic communities.

Abstract INTRODUCTION In Brazil, Biomphalaria glabrata, B. tenagophila, and B. straminea are intermediate hosts of Schistosoma mansoni, the etiological agent of schistosomiasis mansoni. Molluscicide use is recommended by the WHO for controlling the transmission of this parasite. Euphorbia milii latex has shown promising results as an alternative molluscicide. Thus, a natural molluscicide prototype kit based on freeze-dried E. milii latex was developed and evaluated against Biomphalaria spp. METHODS E. milii latex was collected, processed, and lyophilized. Two diluents were defined for freeze-dried latex rehydration, and a prototype kit, called MoluSchall, was produced. A stability test was conducted using prototype kits stored at different temperatures, and a toxicity assay was performed using Danio rerio. Additionally, MoluSchall was tested against B. glabrata under semi-natural conditions according to defined conditions in the laboratory. RESULTS MoluSchall was lethal to three Brazilian snail species while exhibiting low toxicity to D. rerio. Regardless of storage temperature, MoluSchall was stable for 24 months and was effective against B. glabrata under semi-natural conditions, with the same LD100 as observed under laboratory conditions. CONCLUSIONS MoluSchall is a natural, effective, and inexpensive molluscicide with lower environmental toxicity than existing molluscicides. Its production offers a possible alternative strategy for controlling S. mansoni transmission.

Abstract Schistosomiasis is a fatal disease that has a negative impact on health and economics. Praziquantel (PZQ) is the drug of choice for schistosomiasis treatment, but it has no prophylactic effect; therefore, vaccination is an essential requirement in schistosomiasis control. This work was carried out to investigate the possible effect of DNA vaccination against Schistosoma mansoni infection using recombinant S. mansoni fatty acid binding protein (rsmFABP). The smFABP gene was cloned into the eukaryotic expression vector pcDNAI/Amp in order to obtain an smFABP-pcDNAI recombinant plasmid (DNA vaccine) and was used for the intramuscular DNA vaccination of out-bread Swiss albino mice prior to infection with S. mansoni cercariae. Infected groups, either DNA vaccinated or unvaccinated, were treated with PZQ at week 6 post-infection. After 8 weeks post-infection, all mouse groups were sacrificed and parasitological, immunological and histopathological parameters were studied. DNA vaccinated mice showed a high titer of anti-smFABP-IgG antibodies and acquired significant protection (74.2%, p < 0.01) against S. mansoni infection, with a reduction in ova and granuloma counts. DNA vaccinated and PZQ treated animals had higher titers of anti-smFABP-IgG antibodies and decreased (87%, P < 0.001) parenchymal granulomas compared to the DNA vaccinated PZQ untreated group. Infected mice, either non DNA vaccinated or vaccinated, had very high collagen content and fibrous granulomas (74%) compared to the PZQ treated group (10.3% fibrous granuloma) and PZQ treated + DNA vaccinated group (0% fibrous granuloma). In conclusion, DNA vaccination had protective and anti-pathological effects in naive mice and greatly improved the pathological status in PZQ-treated animals, suggesting an immunological and pathological modulating effect of PZQ treatment. Graphical abstract Image Highlights • Schistosomiasis is a fatal disease that has a health and economic negative feedback. • smFABP gene was cloned into the dual expression vector pcDNAI/Amp. • Purified protein was used for intramuscular DNA vaccination. • Vaccine could reduce the oogram pattern, egg count and histopathology. • It could reduce the severity of pathogenicity (works as anti-pathology Vaccine). [ABSTRACT FROM AUTHOR]

Background: Schistosomiasis remains a public health problem in many regions of the world, including Nigeria. Current control strategy involves mass drug administration with praziquantel to the endemic population. To complement and sustain on-going preventive chemotherapy, we developed a health educational game named Schisto and Ladders ™ and tested its potential for the control of schistosomiasis among schoolchildren living in Imala-Odo, a highly endemic community near Abeokuta, Nigeria. Methods: One hundred school children were randomly selected and divided into intervention and control groups through balloting. Their knowledge, attitudes and practices (KAP) concerning schistosomiasis transmission, control and prevention were assessed using structured questionnaires. Schisto and Ladders™ game were given to the intervention group and the popular Snake and Ladders™ game to the control group. Both games were played for 2 months under the supervision of their class teachers. A post-KAP assessment was carried out in both groups, including focus group discussions (FGDs) to investigate knowledge and the impact of the games. Results: Knowledge about urinary schistosomiasis and its transmission significantly improved (P = 0.000) in the intervention group (68.0%) compared to the control group (8.0%). FGDs showed that the frequency of visits to dam water also significantly reduced (P = 0.048) in the intervention group (18.0%) compared to the control group (40.0%). There was a significant increase in knowledge regarding risk behaviours, prevention and control of schistosomiasis among the intervention group, but no new knowledge gained in the control group. Conclusions: This study demonstrates the potential of the health education game Schisto and Ladders™ for teaching basic health education and promoting behavioural changes among schoolchildren in endemic communities. [ABSTRACT FROM AUTHOR]

A paper published in 1990 by Webbe and El Hag described the progress being made in the control of schistosomiasis with the introduction of a new medicine 'Praziquantel' to treat infected individuals, and the use of a molluscicide 'niclosamide', with which to kill the intermediate host snails. Almost 30 years from the date of publication, the situation in Egypt and indeed globally has changed out of all recognition. Almost every country in Africa has a school health programme to deworm children, each country has a national plan which includes school health, and praziquantel is now donated through the World Health Organization for countries to treat school aged children to protect them from the serious consequences of chronic schistosomiasis. As the socio-economic status in Africa improves the chances seem good for elimination of schistosomiasis as a public health problem in most areas in Africa. [ABSTRACT FROM AUTHOR]

This paper examines recent developments in migration studies. It reviews literature related to the potential role of internal population movement in the occurrence of schistosomiasis in Brazil and modifies Prothero's typology of population movement for use in Brazil. This modified classification system may contribute to a better understanding of schistosome transmission as well as improved research and control programs. The results of this study indicate that population movement in Brazil primarily involves economically-motivated rural-urban and interregional movement. However, several movement patterns have become increasingly important in recent years as a result of changing socioeconomic and urbanisation dynamics. These patterns include urban-urban, intracity and urban-rural movement as well as the movement of environmental refugees and tourists. Little is known about the epidemiological significance of these patterns. This paper also highlights the role of social networks in the decision to migrate and to settle. Prothero's classic population movement typology categorises movement as either one-way migrations or circulations and examines them along spatial and temporal scales. However, the typology must be modified as epidemiological information about new patterns becomes available. This paper identifies areas that require further research and offers recommendations that can improve the measurement and spatial analysis of the relationship between population movement and schistosomiasis.

School-aged children (6-15 years) from the endemic area of Pernambuco were evaluated both as a target group for and an indicator of schistosomiasis control in the community. Parasitological data were drawn from baseline stool surveys of whole populations that were obtained to diagnose Schistosoma mansoni infection. Nineteen representative localities were selected for assessing the prevalence of schistosomiasis among individuals in the following age groups: 0-5, 6-15, 16-25, 26-40 and 41-80 years. For each locality, the prevalence in each age group was compared to that of the overall population using contingency table analysis. To select a reference group, the operational difficulties of conducting residential surveys were considered. School-aged children may be considered to be the group of choice as the reference group for the overall population for the following reasons: (i) the prevalence of schistosomiasis in this age group had the highest correlation with the prevalence in the overall population (r = 0.967), (ii) this age group is particularly vulnerable to infection and plays an important role in parasite transmission and (iii) school-aged children are the main target of the World Health Organization in terms of helminth control. The Schistosomiasis Control Program should consider school-aged children both as a reference group for assessing the need for intervention at the community level and as a target group for integrated health care actions of the Unified Health System that are focused on high-risk groups.

This work had the objective of assessing the present epidemiological situation regarding schistosomiasis through performing Kato-Katz coproscopic tests on representative samples of schoolchildren from each of the 43 municipality of endemic area of the state of Pernambuco, Brazil. The methodology is recommended by the World Health Organization to conduct sampled surveys among children at elementary school levels, ideal target group for baseline surveys: (i) schools are accessible; (ii) the greatest prevalence of schistosomiasis is found within this group; (iii) the data gathered from this age group can be used for intervention within the community as a whole. The following infection indicators were utilized: positivity (percentage of individuals examined with eggs of Schistosoma mansoni in the feces) and severity (geometric mean number of eggs per gram of feces, epg). These indicators allowed the area in general and the municipalities in particular to be categorized into prevalence and severity classes for S. mansoni. The prevalence classes were: low ( 10 and < 50%), and high (> 50%); the severity classes were: low (1-99 epg), moderate (100-399 epg), and severe (> 400 epg). For the geohelminthic diseases, the following indicators were used: positivity for each geohelminth (percentage of individuals examined with eggs of geohelminths), and cumulative positivity (percentage of individuals examined with eggs of at least one geohelminth). The municipalities were categorized by means of their cumulative positivity into the following geohelminth prevalence classes (WHO 2002): low (< 50%), medium (> 50 and < 70%), and high (> 70%). The study covered 271 schools in 179 different localities, thus giving a total of 11,234 examinations performed. The overall positivity for S. mansoni was 14.4% and the egg count for this parasite in the feces gave a geometric mean of 67.9 epg which suggests a low general state of infection. These results allow this mesoregion to be categorized as presenting medium prevalence and low severity of schistosomiasis. The overall positivity rates for the geohelminths, Ascaris lumbricoides, Ancylostomidae, and Trichuris trichiura were, respectively, 30.4, 10.1, and 27.8%; the cumulative positivity was 45.4%. These results allow this mesoregion to be categorized as presenting low prevalence of geohelminthic diseases. The data show some municipalities in Pernambuco with prevalence greater than 20%, while others presented parasite loads greater than 100 epg. These indicators attest to the significant morbidity due to schistosomiasis regarding to the severity of infections established in young populations.

Background: Schistosoma parasites sustain a complex transmission process that cycles between a definitive human host, two free-swimming larval stages, and an intermediate snail host. Multiple factors modify their transmission and affect their control, including heterogeneity in host populations and environment, the aggregated distribution of human worm burdens, and features of parasite reproduction and host snail biology. Because these factors serve to enhance local transmission, their inclusion is important in attempting accurate quantitative prediction of the outcomes of schistosomiasis control programs. However, their inclusion raises many mathematical and computational challenges. To address these, we have recently developed a tractable stratified worm burden (SWB) model that occupies an intermediate place between simpler deterministic mean worm burden models and the very computationally-intensive, autonomous agent models. Methods: To refine the accuracy of model predictions, we modified an earlier version of the SWB by incorporating factors representing essential in-host biology (parasite mating, aggregation, density-dependent fecundity, and random egg-release) into demographically structured host communities. We also revised the snail component of the transmission model to reflect a saturable form of human-to-snail transmission. The new model allowed us to realistically simulate overdispersed egg-test results observed in individual-level field data. We further developed a Bayesian-type calibration methodology that accounted for model and data uncertainties. Results: The new model methodology was applied to multi-year, individual-level field data on S. haematobium infections in coastal Kenya. We successfully derived age-specific estimates of worm burden distributions and worm fecundity and crowding functions for children and adults. Estimates from the new SWB model were compared with those from the older, simpler SWB with some substantial differences noted. We validated our new SWB estimates in prediction of drug treatment-based control outcomes for a typical Kenyan community. Conclusions: The new version of the SWB model provides a better tool to predict the outcomes of ongoing schistosomiasis control programs. It reflects parasite features that augment and perpetuate transmission, while it also readily incorporates differences in diagnostic testing and human sub-population differences in treatment coverage. Once extended to other Schistosoma species and transmission environments, it will provide a useful and efficient tool for planning control and elimination strategies. [ABSTRACT FROM AUTHOR]

Este trabalho notifica a ocorrência de um surto de esquistossomose aguda na praia de Porto de Galinhas, Pernambuco, Brasil, quando 662 pessoas tiveram diagnóstico positivo para Schistosoma mansoni. A infecção humana em massa ocorreu no feriado de 7 de setembro, quando chuvas pesadas provocaram a enchente do rio Ipojuca que invadiu as residências. A maioria dos casos agudos foi representada por famílias de residentes locais que tiveram exposição diária às cercárias durante três semanas, até que as águas baixassem. O inquérito malacológico aponta para a possibilidade dos caramujos vetores terem sido introduzidos na localidade com os aterros realizados em quintais, onde vieram a se reproduzir em criadouros peridomiciliares. A infecção dos moluscos se deu a partir de vazamentos de fossas. Os resultados da clínica e do laboratório apontam para cerca de 62% de casos agudos. Estudos complementares estão sendo realizados, para a melhor compreensão deste evento epidemiológico de significativa magnitude para os órgãos de saúde pública e impacto para a população afetada.We recently confirmed several cases of acute schistosomiasis in Porto de Galinhas beach, Northeast Brazil. A total of 662 patients were diagnosed by parasitological and clinical examinations. The infection likely occurred during the September 7 national holiday, when heavy rainfall flooded the Ipojuca River and people were infected when the water covered their yards. Families were continuously exposed to infection for a period of three weeks until the water had completely dried up. Previous investigation suggests that snail vectors were introduced as a result of landfill in marshy areas. The swamp-flooding of such areas facilitated the emergence of slums surrounded by snail breeding sites. Heavy rainfall caused open-air sewage ditches to overflow, allowing for infection of snails by Schistosoma mansoni. Thus, continuous floods were responsible for the spread of human infection. Clinical and laboratory results identified 62% of acute cases of S. mansoni. Complementary studies are being conducted to define the impact and epidemiological meaning of the acute schistosomiasis outbreak.

The subject of this conference reflects the scientific community's interest in seeking to understand the complex causal web whose various social, economic, and biological components interact in the production and reproduction of schistosomiasis and its control in relation to community participation. From the onset, the author stresses the impossibility of dealing separately with community participation, as if social components were just one more "weapon" in the arsenal for schistosomiasis control. This study begins with a brief historical review of the 71 years of control activities with this endemic disease, stressing the enormous efforts and huge expenditures in this field vis-à-vis the limited results, despite the extraordinary technological development of specific, classical control inputs such as new treatment drugs and molluscicides. The article then discusses the various strategies used in control programs, emphasizing ideological consistencies and contradictions. Interactions at the macro and micro levels are discussed, as are the determinants and risk factors involved in producing the disease's endemicity. Unequal occupation of space leaves the segregated portion of the population exposed to extremely favorable conditions for transmission of the disease. This raises the issue of how to control an endemic disease which is so closely linked to the way of life imposed on the population. The study challenges the classical control model and suggests an alternative model now undergoing medium-term investigation in the States of Espirito Santo, and Pernambuco, Brazil. The author concludes that we do not need new strategies, but a new control model, contrary to the prevailing classical model in both concept and practice. From the conceptual point of view, the new model mentioned above is different from others in that schistosomiasis control is seen from a social perspective stressing the population's accumulated knowledge in addition to the building of shared knowledge. The model's praxis has the following characteristics: (1) it is integrated with and financed by research agencies and health services; (2) it operates at the local health services level; (3) use of molluscicides has been eliminated; (4) emphasis is given to individual medical treatment and improvement of sanitary conditions.

Attempts to control schistosomiasis have hitherto involved the use of one or more of the following methods, either in isolation or in combination: (1) control of the intermediate host using molluscicides or biological methods; (2) basic sanitation and clean water supply; (3) health education; (4) individual or mass treatment; (5) protection of individuals in such a way as to prevent cercariae from penetrating the skin; (6) vaccine-based strategies against schistosomiasis. None of these methods is capable, on its own, of bringing about effective control of schistosomiasis, except in populations of a very limited size or under very special conditions. Molluscicides, besides expensive and toxic, have only a temporary effect. As for biological control, there is no effective method yet. Basic sanitation and clean water supply combined with health education potentially constitute the most effective approach, but only in the mid-to-long term. Mass treatment reduces morbidity, but does not control transmission. Protection of individuals has proved to be impracticable on a large scale. Vaccine-based strategies against schistosomiasis are still in the experimental stage. Experiments carried out in Brazil in the last 20 years have shown that mass treatment with single doses of oxamniquine or praziquantel can rapidly reduce levels of Shistosoma mansoni infection and morbidity in endemic areas. They have also shown that subsequent transmission and reinfection frequently occur in defined foci or "clusters", due to human contact with water, and in inverse proportion to the number and frequency of treatments carried out. On the basis of these experiments, the author suggests a multidisciplinary strategy for schistosomiasis control.

Schistosomiasis control was impossible without effective tools. Synthetic molluscicides developed in the 1950s spearheaded community level control. Snail eradication proved impossible but repeated mollusciciding to manage natural snail populations could eliminate transmission. Escalating costs, logistical complexity, its labour-intensive nature and possible environmental effects caused some concern. The arrival of safe, effective, single-dose drugs in the 1970s offered an apparently better alternative but experience revealed the need for repeated treatments to minimise reinfection in programmes relying on drugs alone. Combining treatment with mollusciciding was more successful, but broke down if mollusciciding was withdrawn to save money. The provision of sanitation and safe water to prevent transmission is too expensive in poor rural areas where schistosomiasis is endemic; rendering ineffective public health education linked to primary health care. In the tropics, moreover, children (the key group in maintaining transmission) will always play in water. Large scale destruction of natural snail habitats remains impossibly expensive (although proper design could render many new man-made habitats unsuitable for snails). Neither biological control agents nor plant molluscicides have proved satisfactory alternatives to synthetic molluscicides. Biologists can develop effective strategies for using synthetic molluscicides in different epidemiological situations if only, like drugs, their price can be reduced.