Mapping of intermediate host snails for schistosomiasis in the Democratic Republic of Congo: a systematic review.

Schistosomiasis is a snail-borne disease that has a considerable impact on human and animal health, particularly in sub-Saharan Africa. The intermediate hosts of the schistosome parasites are freshwater snails of the genera Biomphalaria Preston, 1910 and Bulinus Müller, 1781. In order to identify existing gaps in the spread of the disease in the Democratic Republic of Congo (DRC), this study compiled the available knowledge of the distribution, population dynamics and ecology of the intermediate hosts of schistosomiasis. A systematic literature search was conducted in PubMed, Embase and Scopus for all malacological studies on schistosoma intermediate hosts in DRC published between 1927 and October 2022. A total of 55 records were found, of which 31 met the inclusion criteria: these were published field and experimental studies conducted in the DRC and focused on snails as intermediate hosts of schistosomes. The analysis of these studies revealed that more up-to-date data on the distribution of snail intermediate hosts in the DRC are needed. Moreover, ecological factors have been less studied for Bulinus species than for Biomphalaria species. These factors play a crucial role in determining suitable snail habitats, and the lack of comprehensive information poses a challenge in snail control. This review makes it clear that there are no current malacological data in the DRC. There is a clear need for molecular and ecological research to update the exact species status and population dynamics of all potential intermediate host species. This will facilitate targeted snail control measures that complement drug treatment in the control of schistosomiasis in the country.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

DNA barcoding as a valuable tool for delimiting mollusk species of the genus Biomphalaria Preston, 1910 (Gastropoda: Planorbidae).

Introduction: The genus Biomphalaria in Brazil includes 11 species and one subspecies, three of which are intermediate hosts of Schistosoma mansoni. Due to the recent evolution of this group, some species are difficult to identify based on morphological characters, making the use of genetic markers necessary for species identification. This study aimed to evaluate the use of partial sequences of the cytochrome c oxidase I (coi) gene for the identification of Biomphalaria species using phylogenetic reconstruction and species delimitation algorithms. The study tested the use of DNA barcoding technique for species delimitation within the genus. Methods: DNA barcoding was performed by sequencing a partial region of the coi gene from specimens, and the sequences were analyzed using phylogenetic reconstruction and algorithms to delimit Operational Taxonomic Units (OTUs). Results: The study found that the use of the coi gene in the reconstruction of the phylogeny of the genus might be an alternative for understanding the evolution and dispersion of species. However, this marker alone is not enough to solve complex taxonomic problems within the genus. A total of 223 sequences were analyzed, 102 of which could be separated using the barcode gap, enabling the correct identification of seven taxa. Discussion: The study demonstrated that accurate mollusk identification is necessary for effective schistosomiasis control. The DNA barcoding methodology was found to be promising for accurate mollusk identification, which is crucial for concentrating schistosomiasis control efforts in places where it is needed.

A new semi-slug of the genus Microparmarion from Brunei, discovered, described and DNA-barcoded on citizen-science 'taxon expeditions' (Gastropoda, Stylommatophora, Ariophantidae).

Background: During citizen-science expeditions to the Ulu Temburong National Park, Brunei, several individuals were collected of a semi-slug species of the genus Microparmarion that, based on morphology and in-the-field DNA-barcoding, was found to be an undescribed species. New information: In this paper, we describe Microparmarionsallehi Wu, Ezzwan & Hamdani, n. sp., after field centre supervisor Md Salleh Abdullah Bat. We provide details on the external and internal reproductive morphology, the shell and the ecology of the type locality, as well as a diagnosis comparing it with related species. DNA barcodes were generated for five individuals and used for a phylogenetic reconstruction. Microparmarionsallehi sp. n. and M.exquadratus Schilthuizen et al., 2019 so far are the only Bornean species of the genus that live in lowland forest; other species are found in montane forests.

Liguus Landscapes: Amateur Liggers, Professional Malacology, and the Social Lives of Snail Sciences.

Malacologists took notice of tree snails in the genus Liguus during the last decades of the nineteenth century. Since then, Liguus have undergone repeated shifts in identity as members of species, states, shell collections, backyard gardens, and engineered wildernesses. To understand what Liguus are, this paper examines snail enthusiasts, collectors, researchers, and conservationists-collectively self-identified as Liggers-in their varied landscapes. I argue that Liguus, both in the scientific imaginary and in the material landscape, mediated knowledge-making processes that circulated among amateur and professional malacologists across the United States and Cuba during the twentieth century. Beginning with an examination of early Liggers' work in Florida and Cuba, this paper demonstrates how notions of taxonomy and biogeography informed later efforts to understand Liguus hybridization and conservation. A heterogeneous community of Liggers has had varied and at times contradictory commitments informed by shifting physical, social, and scientific landscapes. Genealogizing those commitments illuminates the factors underpinning a decision to undertake the until now little-chronicled large-scale and sustained transplantation of every living Floridian form of Liguus fasciatus into Everglades National Park. The social history of Liggers and Liguus fundamentally blurs distinctions between professional scientists and amateur naturalists. The experiences of a diverse cast of Liggers and their Liguus snails historicize the complex character of human-animal relations and speak to the increasing endangerment of many similarly range-restricted invertebrates.

High prevalence of urinary schistosomiasis in a desert population: results from an exploratory study around the Ounianga lakes in Chad.

BACKGROUND: Researching a water-borne disease in the middle of the Sahara desert might not seem the most relevant concern. However, nomadic Sahelian pastoralists health concerns regarding their livestock and anecdotal reports about trematode infections of Fasciola spp. and Schistosoma spp. in desert-raised animals justified an exploratory study focusing on the lakes of Ounianga in Northern Chad. The aim was to test whether trematode parasites such as Schistosoma spp. occur in human populations living around the Sahara desert lakes of Ounianga Kebir and Ounianga Serir in northern Chad. METHODS: The study was carried out in January 2019 and comprised of three components. First, a cross sectional survey based on a random sample drawn from the population to detect infections with S. haematobium and S. mansoni; second, focus group discussions exploring disease priorities, access to health and health seeking behaviour; and third, surveying water contact sites for intermediate host snails. Samples of trematode parasites and snails were confirmed on species level by molecular genetic methods. For parasitological and malacological surveys descriptive statistics were performed. Qualitative data analysis included the full review of all transcripts, followed by a descriptive and explorative thematic analysis. RESULTS: Among 258 participants, the overall S. haematobium prevalence using urine filtration was 39.2% [95% confidence interval (CI): 33.5-45.1%], with 51.5% of the infected suffering from heavy infection. The intermediate host snail of S. haematobium (Bulinus truncatus) occurred at water contact sites near both study villages, revealing the potential for local transmission. Although a positive S. mansoni point-of-care circulating cathodic antigen (POC-CCA) test result was obtained from 8.6% (95% CI 5.7-12.8%) of the samples, no intermediate host snails of S. mansoni were found, and the relevance of S. mansoni remains uncertain. Qualitative findings underline the importance of morbidity caused by urinary schistosomiasis, and the lack of access to diagnostics and treatment as a major health concern. CONCLUSIONS: This research revealed a high prevalence of urinary schistosomiasis in the population living around the lakes of Ounianga in the Sahara, a United Nations Educational, Scientific and Cultural Organization (UNESCO) world heritage site in Chad. Despite the high public health importance of the associated morbidity expressed by the population, there is no access to diagnostics and treatment. Further work is needed to develop and test a context-adapted intervention.

Schistosomiasis in Gabon from 2000 to 2021 - A review.

INTRODUCTION: Schistosomiasis is a public health issue of concern in Gabon, with the disease being reported from all regions of the country. The topic has been of interest for the local researchers and physicians for over two decades. The objective of this narrative review was to provide an overview of the research activities in the area from 2000 to early 2021. METHODS: We performed a narrative literature review. The search strategy was designed to get a broad overview of the different research topics on schistosomiasis and the national control programme, and included grey literature. RESULTS: A total of 159 articles was screened, and 42 were included into the review in addition to the grey literature. During the past two decades, the work on schistosomiasis originated from five out of the nine provinces of the country, with diverse aspects of the disease investigated; including immunology, epidemiology, diagnosis and treatment. Several studies investigated various aspects of schistosomiasis-related morbidity in the respective study populations. The body of work demonstrates that much effort was made to understand the details of the host immune response to schistosomiasis, and the immune profile changes induced in patients treated with praziquantel. Although some MDA campaigns were conducted in the country; little, however, is known on the epidemiological situation of the disease, particularly of its distribution within the population, as well as co-infections with other parasitic diseases also endemic in the area. CONCLUSION: Progress has been made over the past two decades in the understanding of schistosomiasis in the country, including disease-related morbidity and its interaction with other parasitic infections, and the immunology and epidemiology of the disease. However, for optimising control of the disease, there is a need to fine-tune these findings with detailed local epidemiological and malacological data. We call for such studies to accomplish the knowledge of schistosomiasis in the country, particularly in areas of moderate or high endemicity, and recommend this approach to comparable schistosomiasis-endemic areas elsewhere.

A new giant keelback slug of the genus Limax from the Balkans, described by citizen scientists.

Background: Despite their large size, striking colouration and genital extravagance, the taxonomy of the European giant keelback slugs of the genus Limax is still poorly understood. Preliminary morphological and molecular data suggest that many unnamed or unrecognised species exist, especially in the Alps, the Mediterranean and the Balkans. New information: We organised a citizen science expedition to Durmitor National Park in Montenegro and discovered a new species, genetically distinct, but morphologically similar to the sympatric L.cinereoniger Wolf 1803 and describe it as L.pseudocinereoniger.

Malacological survey along the intertidal zone of Las Piñas-Paranaque Critical Habitat and Ecotourism Area

Background@#One of the eight Ramsar sites in the Philippines is the Las Piňas – Parañaque Critical Habitat and Ecotourism Area(LPPCHEA), and it plays a significant role in the East Asian-Australian Flyway as a stopover site. The migratory birds coming from the north of Asia and Alaska feed on the molluscs in this area. However, there is paucity of literature on the species composition of molluscs found in this critical habitat. Baseline information on these organisms is essential as they are subject to the effects of anthropogenic activities close to and in the wetland, which in turn can have an impact on the ecosystem, particularly the birds foraging in this location. @*Methodology@#The Natural Geography of in-Shore areas (NaGISA) protocol was used for the study. Transects were laid in three sampling sites in Freedom Island and Long Island. The sampling sites were GPS-referenced. A cylinder corer was used to collect mudflat soil, with the corer pushed into the sediment. Soil samples were sieved using a 0.5mm stainless mesh sieve pan, leaving shells and larger sand grains. The molluscs were sorted and identified through taxonomic keys. Sampling was done once for each site in November 2012. @*Results and Discussion@#A total of 61 molluscan species belonging to two classes, 14 orders, and 33 molluscan families were identified and recorded. There were 34 species under the Class Gastropoda that belong to 5 orders and 18 families. For Class Bivalvia, there were 27 species belonging to 8 orders and 15 families. Among the molluscs recorded, 10 species were identified as non-indigenous. It is important to monitor molluscan species as anthropogenic activities may affect these organisms, and in turn, affect the wetland's function for migratory birds. The presence of non-indigenous species may be a potential threat to the ecosystem.@*Conclusion@#Baseline information of the molluscan community in the LPPCHEA was provided by the study. These species provide diet to the endemic and migratory birds in the area. There is a need to monitor these molluscs due to the effects of the man-caused activities close to the area. Also, the non-indigenous species should be studied for their potential to be invasive.

A new Diancta species of the family Diplommatinidae (Cyclophoroidea) from Vanua Levu Island, Fiji.

A new species of Diancta of the staircase snail family Diplommatinidae is described from Mt. Savusavu, Vanua Levu Island, Fiji. Due to its left coiling shell and a constriction before the last whorl, it is placed in the genus Diancta. Micro-CT imaging reveals two apertural teeth and an inner lamella that is situated at the zone of constriction. The shell abruptly changes coiling direction by 45 degrees before the last whorl. Up to now, this coiling modus had not yet been documented for any species of Diplommatinidae from the Fiji Islands.

Type specimens in the molluscan collection of the Bailey-Matthews National Shell Museum, Florida, USA.

This article lists and comments on the primary and secondary types represented in the collection of the Bailey-Matthews National Shell Museum (BMSM), on Sanibel, Florida, USA. The collection includes 464 type specimens, of which 15 are holotypes, representing 149 taxa, of which 145 are species and four subspecies. The BMSM collection is fully catalogued and posted online via the Museum's website, in addition to iDigBio and GBIF. The publication of this annotated list intends to improve on the accessibility and promote this important group of name-bearing specimens, which includes, among other cases, types originating from orphaned collections and material poorly documented in the original descriptions. Eighty-two types were selected for illustration, and the photos of all BMSM types are available as part of the BMSM online collection catalog.

Spatial and seasonal distribution of Bulinus globosus and Biomphalaria pfeifferi in Ingwavuma, uMkhanyakude district, KwaZulu-Natal, South Africa: Implications for schistosomiasis transmission at micro-geographical scale.

BACKGROUND: Schsistosomiasis is endemic in sub-Saharan Africa. It is transmitted by intermediate host snails such as Bulinus and Biomphalaria. An understanding of the abundance and distribution of snail vectors is important in designing control strategies. This study describes the spatial and seasonal variation of B. globosus and Bio. pfeifferi and their schistosome infection rates between May 2014 and May 2015 in Ingwavuma, uMkhanyakude district, KwaZulu-Natal province, South Africa. METHODS: Snail sampling was done on 16 sites once every month by two people for 30 min at each site using the scooping and handpicking methods. Snails collected from each site were screened for schistosome mammalian cercariae by the shedding method. The negative binomial generalised linear mixed model (glmm) was used to determine the relationship between abundances of the intermediate host snails and climatic factors [rainfall, land surface temperatures (LST), seasons, habitats, sampling sites and water physico-chemical parameters including pH and dissolved oxygen (DO)]. RESULTS: In total, 1846 schistosomiasis intermediate host snails were collected during the study period. Biompharia pfeifferi was more abundant (53.36%, n = 985) compared to B. globosus (46.64%, n = 861). Bulinus globosus was recorded at 12 sites (75%) and Bio. pfeifferi was present at 7 sites (43.8%). Biompharia pfeifferi cohabited with B. globosus at all the sites it was present. High numbers of Bio. pfeifferi (n = 872, 88.5%) and B. globosus (n = 705, 81.9%) were found between winter and mid-spring. Monthly rainfall showed a statistically significant negative relationship with the abundance of B. globosus (p < 0.05). Dissolved oxygen (DO) had a statistically significant positive relationship with the abundance of Bio. pfeifferi (p < 0.05) while (LST) had a statistically significant negative relationship (p < 0.05). More B. globosus (8.9%, n = 861) were shedding schistosome mammalian cercariae compared to Bio. pfeifferi (0.1%, n = 985) confirming the already documented high prevalence of S. haematobium in Ingwavuma compared to S. mansoni. CONCLUSION: Results of this study provide updated information on the distribution of schistosomiasis intermediate host snails in the study area and contributes towards the understanding of the transmission dynamics of schistosomiasis at the micro-geographical scale in this area.

Malacological survey to identify transmission sites for intestinal schistosomiasis on Ijinga Island, Mwanza, north-western Tanzania.

The role of malacological surveys to identify potential transmission sites for schistosomiasis control in this era of mass drug administration have received little attention. In that context, the present study was conducted to determine the abundance, identity and disease transmission potential of intermediate host snails for intestinal schistosomiasis on Ijinga Island, north-western Tanzania. A cross-sectional malacological study was conducted between February and March 2016 on Ijinga Island, Lake Victoria, north-western Tanzania. Snails were collected at points where humans are in frequent contact with water using a standardized scooping technique and have been identified using shell morphological features. The Schistosoma infection status of the collected snails was determined by using real-time Polymerase Chain Reaction (real-time PCR). A total number of 4,888 snails were putatively identified as Biomphalaria species. A random sample of 788 snails underwent molecular analyses for Schistosoma infection. Overall, 279 (35.4%) of Biomphalaria species were identified to be infected with parasites of the lateral spined S. mansoni group. The findings confirm that Biomphalaria species collected in areas with high human water contacts are infected with Schistosoma and that there is a likeliness of local risk for schistosomiasis transmission at most water contact points around Ijinga Island.

Type specimens of Caudofoveata (Mollusca, Aplacophora) in the molluscan collections of the National Museum of Natural History, Smithsonian Institution, and of the Museum of Comparative Zoology, Harvard University.

The type material of Caudofoveata (Aplacophora) deposited in the molluscan collections of the National Museum of Natural History, Smithsonian Institution (USNM), and of the Museum of Comparative Zoology, Harvard University (MCZ), USA, are listed. An extensive analysis of the databases and a curatorial revision of all lots from both collections were made, including an examination of material from Dr. Amelie Scheltema's personal collections, recently donated and under curation in the MCZ. A total of 2313 specimens from 378 type lots representing 33 nominal species group taxa was found. Of these, 2275 specimens from 358 lots representing 27 species are held in the USNM (22 holotypes, 2 syntypes and 334 paratypes) and 38 specimens from 20 lots representing 7 species are in the MCZ (5 syntypes, 9 paratypes, 3 paralectotypes, 3 doubtful paralectotypes). Some taxonomical notes about these species and their type-materials are provided.

Cryptic intermediate snail host of the liver fluke Fasciola hepatica in Africa.

BACKGROUND: Snails such as Galba truncatula are hosts for trematode flukes causing fascioliasis, a zoonosis that is a major public health problem. Galba truncatula has recently been shown to be a cryptic species complex. African populations of Galba spp. are not yet studied using molecular assessments and is imperative to do so and reconstruct the centre of origin of Galba and to understand when and by what means it may have colonized the highlands of Africa and to what extent humans might have been involved in that process. METHODS: Samples from all known sub-ranges throughout Africa and new samples from Europe and Asia were obtained. We used a combination of two mitochondrial (cox1 and 16S) and one nuclear (ITS2) markers and phylogenetic, divergence time estimates and phylogeographical methods to determine the identity and biogeographical affinities. We also reconstructed the colonization history including the likely mode of dispersal and tested for the presence of cryptic Galba species in Africa. RESULTS: Galba truncatula is restricted to the Palaearctic region of the continent, namely Morocco. All sub-Saharan populations proved to be a distinct species according to the phylogenetic analyses and genetic distance. We propose to use the existing name Galba mweruensis (Connolly, 1929) for this species which is morphologically indistinguishable from the other two species hitherto known to occur in northern Africa, i.e. G. truncatula and G. schirazensis. Sub-tropical Africa has been colonized only once in either the Pliocene and possibly Miocene. Diversification within G. mweruensis is dated to the Plio-Pleistocene and thus human-mediated dispersal can be ruled out for the initial colonization of the isolated mountain ranges. There are potentially even more cryptic species in high altitude areas of Africa as outlined by the distinctness of the population found at the top of Mt. Elgon, Uganda. CONCLUSIONS: From a novel genetic inspection of available African material, a hitherto neglected distinct species, G. mweruensis, now appears a major host of F. hepatica throughout sub-Saharan Africa. A closer examination of trematode parasites hosted by this species is needed in order to understand transmission patterns in highlands throughout eastern and southern Africa. We encourage future studies to inspect other high altitudes areas in Africa in light of parasites of either veterinary or medical importance.

The (almost) unknown Italian naturalist Raffaello Bellini (1874-1930): biography, malacological publications, and status of his recent molluscan taxa.

Raffaello Bellini (1874-1930) was an almost unknown Italian naturalist who produced a wide scientific literature. He followed the "Golden Age" of the Neapolitan Malacological School and his malacological papers were particularly related to Italy, focusing on marine, freshwater, fossil, and terrestrial species. We hereby highlight and summarize Raffaello Bellini's biography and malacological work, and revise the status of recent molluscan taxa described by him. Our bibliographic research revealed that from 1897 to 1929 Bellini published 41 papers dealing with malacology and altogether instituted 46 molluscan nominal taxa, 17 of which are based on fossil samples and 29 on recent samples. Within the latter group, 24 (13 marine, nine terrestrial, and two freshwater) taxa are potentially available, whilst five (two marine and three terrestrial) are nomina nuda. Among these 24 taxa, 13 are available, ten have infrasubspecific rank and thus are not available, and one is permanently invalid. Among available binomial names, seven are junior synonyms of valid taxa and six are nomina dubia. Gibbula umbilicaris var. acherusiae Bellini, 1903 is here considered a junior synonym of Gibbula ardens (Salis Marschlins, 1793) for the first time. Finally, three recent marine molluscan taxa were named after Raffaello Bellini. However, none of these species proved to be valid. The present paper sheds light on the work done by the latest of the "early" authors of the Neapolitan Malacological School and contributes to nomenclature and taxonomy of Recent European molluscan taxa.

Ecological and Parasitological Study on Cerithidea cingulata (Gastropoda) in Hormoz Strait Littoral, South of Iran.

BACKGROUND: "Cerithidea cingulata" is reported from south of Iran, may act as intermediate host of Heterophyes heterophyes and cercaria dermatitis. As parasitological aspects of this brackish snail were not studied in Iran, this study was conducted in 2016, in Hormoz Strait, south of Iran. METHODS: Totally 402 snails were collected from 36 locations of three main regions in Hormozgan Province, Iran in 2015. In each location, one square meter was checked, and snails were collected for parasitological study. Snails were crashed and cercariae were studied using light microscope, in some cases natural red staining was used for better resolution. RESULTS: Mean length of snails was about 20.33 mm, width 5.57 mm. The aperture length was 5.10 and spire was 15.22. Important founded cercaria was cysticercus cercariae, echinostoma cercaria, furcocercus cercaria, furcocystocercous cercaria, gastrostomy cercaria, gymnocephalus cercaria, monostome cercaria, pelurolophocercus cercaria and xiphidiocercaria. CONCLUSION: The presence of this snail is reported from Persian Gulf to western Pacific in China. Our study showed a pattern of infection in local area and was compatible with other studies. Importance of C. cingulata as intermediate host of some medically important disease should be considered and other complementary molecular studies for exact identification of cercaria are necessary.

Clinico-epidemiology, malacology and community awareness of Schistosoma mansoni in Haradenaba and Dertoramis kebeles in Bedeno district, eastern Ethiopia.

BACKGROUND: Schistosoma mansoni is a major public health problem. Different studies reported unidentified sites in Ethiopia with variable prevalence and intensity, but there is no report from this study area. OBJECTIVE: To assess the clinico-epidemiology, malacology, risk factors, and community awareness of S. mansoni in Haradenaba and Dertoramis kebeles in the Bedeno district, eastern Ethiopia. METHODS: A cross-sectional study was conducted among 1011 study participants in 413 systematically selected households from Haradenaba and Dertoramis kebeles from 30 June 2016 to 30 July 2017. Data were collected by using pretested, structured questionnaires, clinical examinations, and stool examinations. Stool samples were processed by the Kato-Katz method and examined microscopically. Snails were collected by scooping from water contact points. Data were analyzed using SPSS, version 16 statistical software. RESULT: The overall prevalence of S. mansoni was 35.7%. Heavy-intensity infection was detected in 8.9% of the study participants. Results included: participants who were unaware about the possible source of infection (adjusted odds ratio: 2.95; 95% confidence interval: 1.25, 7.95), modes of transmission (adjusted odds ratio: 5.51; 95% confidence interval: 3.52, 12.51), prevention (adjusted odds ratio: 4.01; 95% confidence interval: 2.00, 8.75) about schistosomiasis/bilharziasis were more likely infected with S. mansoni than those who were aware. Participants who swim or bathe in the river were more likely infected with S. mansoni than those who do not (adjusted odds ratio: 6.41; 95% confidence interval: 3.15, 11.25). Biomphalaria pfeifferi snails were collected from all water bodies in Haradenaba and Dertoramis, but they did not shed schistosome cercaria in the laboratory. CONCLUSION: S. mansoni infection is found in high magnitude in these study areas, despite not being previously reported. A majority of the study participants had low awareness about the source of infection, mode of transmission, and prevention methods of schistosomiasis. Efforts should be made to improve community awareness about transmission and prevention of schistosomiasis.

Spatial distribution and seasonality of Biomphalaria spp. in São Luís (Maranhão, Brazil).

Two of the three vector species of Schistosoma mansoni Sambon, 1907 in Brazil occur in the state of Maranhão: Biomphalaria glabrata (Say, 1818) and Biomphalaria straminea (Dunker, 1848). For the implementation of effective measures to combat schistosomiasis, it is necessary to identify the spatial and seasonal dynamics of these snails. Therefore, this work brought together information from malacological survey carried out in São Luís (Maranhão, Brazil) to identify the spatial and seasonal distribution patterns of Biomphalaria spp. snails. We used data from malacological surveys of the Municipal Health Secretary of São Luís, conducted between 2006 and 2013 in 23 neighborhoods. We also used data from the mollusk surveys that we conducted for 2 years (2012-2014) in four of these neighborhoods. During the 8-year period (2006-2013), 15,990 specimens of Biomphalaria spp. were collected. There was a positive association between precipitation and the abundance of mollusks of the genus Biomphalaria. During 2012-2014, a total of 2487 snail specimens were obtained (B. glabrata: 1046 specimens; B. straminea: 1426 specimens). There was a positive correlation between precipitation and B. straminea abundance. High density of human occupation and high precipitation are two factors that affect the distribution and density of Biomphalaria spp.