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Schistosomes cause schistosomiasis, the world’s second most important parasitic disease after malaria in terms of public health and social-economic impacts. A peculiar feature of these dioecious parasites is their ability to produce viable and fertile hybrid offspring. Originally only present in the tropics, schistosomiasis is now also endemic in southern Europe. Based on the analysis of two genetic markers the European schistosomes had previously been identified as hybrids between the livestock- and the human-infective species Schistosoma bovis and Schistosoma haematobium, respectively. Here, using PacBio long-read sequencing technology we performed genome assembly improvement and annotation of S. bovis, one of the parental species for which no satisfactory genome assembly was available. We then describe the whole genome introgression levels of the hybrid schistosomes, their morphometric parameters (eggs and adult worms) and their compatibility with two European snail strains used as vectors (Bulinus truncatus and Planorbarius metidjensis). Schistosome-snail compatibility is a key parameter for the parasites life cycle progression, and thus the capability of the parasite to establish in a given area. Our results show that this Schistosoma hybrid is strongly introgressed genetically, composed of 77% S. haematobium and 23% S. bovis origin. This genomic admixture suggests an ancient hybridization event and subsequent backcrosses with the human-specific species, S. haematobium, before its introduction in Corsica. We also show that egg morphology (commonly used as a species diagnostic) does not allow for accurate hybrid identification while genetic tests do., PLoS Neglected Tropical Diseases, 15 (12), ISSN:1935-2727, ISSN:1935-2735

Background Human schistosomiasis is the second most important tropical disease and occurs in two forms in Africa (intestinal and urogenital) caused by the digenetic trematodes Schistosoma mansoni and Schistosoma haematobium, respectively. A proposed recent shift of schistosomiasis above a previously established altitudinal threshold of 1400 m above sea level in western Ugandan crater lakes has triggered more research interest there. Methods Based on extensive field sampling in western Uganda and beyond and employing an approach using sequences of the mitochondrial barcoding gene cytochrome c oxidase subunit 1 (cox1) this study aims were: (i) identification and establishment of the phylogenetic affinities of Bulinus species as potential hosts for Schistosoma spp.; (ii) determining diversity, frequency and distribution patterns of Bulinus spp.; and (iii) establishing genetic variability and phylogeographical patterns using Bayesian inference and parsimony network analyses. Results Out of the 58 crater lakes surveyed, three species of Bulinus snails were found in 34 crater lakes. Bulinus tropicus was dominating, Bulinus forskalii was found in two lakes and Bulinus truncatus in one. The latter two species are unconfirmed potential hosts for S. haematobium in this region. However, Bulinus tropicus is an important species for schistosomiasis transmission in ruminants. Bulinus tropicus comprised 31 haplotypes while both B. forskalii and B. truncatus exhibited only a single haplotype in the crater lakes. All species clustered with most of the haplotypes from surrounding lake systems forming source regions for the colonization of the crater lakes. Conclusions This first detailed malacological study of the crater lakes systems in western Uganda revealed presence of Bulinus species that are either not known or not regionally known to be hosts for S. haematobium, the causing agent of human urogenital schistosomiasis. Though this disease risk is almost negligible, the observed dominance of B. tropicus in the crater lakes shows that there is a likelihood of a high risk of infections with Schistosoma bovis. Thus, extra attention should be accorded to safeguard wild and domestic ruminants in this region as the population benefits from these animals.

Introgression among parasite species has the potential to transfer traits of biomedical importance across species boundaries. The parasitic blood fluke Schistosoma haematobium causes urogenital schistosomiasis in humans across sub-Saharan Africa. Hybridization with other schistosome species is assumed to occur commonly, because genetic crosses between S. haematobium and livestock schistosomes, including S. bovis, can be staged in the laboratory, and sequencing of mtDNA and rDNA amplified from microscopic miracidia larvae frequently reveals markers from different species. However, the frequency, direction, age, and genomic consequences of hybridization are unknown. We hatched miracidia from eggs and sequenced the exomes from 96 individual S. haematobium miracidia from infected patients from Niger and the Zanzibar archipelago. These data revealed no evidence for contemporary hybridization between S. bovis and S. haematobium in our samples. However, all Nigerien S. haematobium genomes sampled show hybrid ancestry, with 3.3–8.2% of their nuclear genomes derived from S. bovis, providing evidence of an ancient introgression event that occurred at least 108–613 generations ago. Some S. bovis-derived alleles have spread to high frequency or reached fixation and show strong signatures of directional selection; the strongest signal spans a single gene in the invadolysin gene family (Chr. 4). Our results suggest that S. bovis/S. haematobium hybridization occurs rarely but demonstrate profound consequences of ancient introgression from a livestock parasite into the genome of S. haematobium, the most prevalent schistosome species infecting humans.

Hybridization is a fascinating evolutionary phenomenon that raises the question of how species maintain their integrity. Inter-species hybridization occurs between certain Schistosoma species that can cause important public health and veterinary issues. In particular hybrids between Schistosoma haematobium and S. bovis associated with humans and animals respectively are frequently identified in Africa. Recent genomic evidence indicates that some S. haematobium populations show signatures of genomic introgression from S. bovis. Here, we conducted a genomic comparative study and investigated the genomic relationships between S. haematobium, S. bovis and their hybrids using 19 isolates originating from a wide geographical range over Africa, including samples initially classified as S. haematobium (n = 11), S. bovis (n = 6) and S. haematobium x S. bovis hybrids (n = 2). Based on a whole genomic sequencing approach, we developed 56,181 SNPs that allowed a clear differentiation of S. bovis isolates from a genomic cluster including all S. haematobium isolates and a natural S. haematobium-bovis hybrid. All the isolates from the S. haematobium cluster except the isolate from Madagascar harbored signatures of genomic introgression from S. bovis. Isolates from Corsica, Mali and Egypt harbored the S. bovis-like Invadolysin gene, an introgressed tract that has been previously detected in some introgressed S. haematobium populations from Niger. Together our results highlight the fact that introgression from S. bovis is widespread across S. haematobium and that the observed introgression is unidirectional., Author summary Hybridization is a fascinating evolutionary phenomenon that raises the question of how species maintain their integrity. Inter-species hybridization occurs between certain Schistosoma species that can cause important public health and veterinary issues. In particular hybrids between Schistosoma haematobium and S. bovis associated with humans and animals respectively are frequently identified in Africa. Recent genomic evidence indicates that some S. haematobium populations show signatures of genomic introgression from S. bovis. Here we conducted a comparative genomic study to assess the genomic diversity within S. haematobium and S. bovis species and genetic differentation at the genome scale between these two sister species over the African continent. We also investigated traces of possible ancient introgression from one species to another. We found that S. haematobium display low genetic diversity compared to S. bovis. We also found that most S. haematobium samples harbor signature of past introgression with S. bovis at some genomic positions. Our results strongly suggest that introgression occurred long time ago and that such introgression is unidirectional from S. bovis within S. haematobium. Such introgresssion event(s) result in diverging patterns of genomic introgression across S. haematobium lineages.

Background Urogenital schistosomiasis, caused by infection with Schistosoma haematobium, is endemic in Niger but complicated by the presence of Schistosoma bovis, Schistosoma curassoni and S. haematobium group hybrids along with various Bulinus snail intermediate host species. Establishing the schistosomes and snails involved in transmission aids disease surveillance whilst providing insights into snail-schistosome interactions/compatibilities and biology. Methods Infected Bulinus spp. were collected from 16 villages north and south of the Niamey region, Niger, between 2011 and 2015. From each Bulinus spp., 20–52 cercariae shed were analysed using microsatellite markers and a subset identified using the mitochondrial (mt) cox1 and nuclear ITS1 + 2 and 18S DNA regions. Infected Bulinus spp. were identified using both morphological and molecular analysis (partial mt cox1 region). Results A total of 87 infected Bulinus from 24 sites were found, 29 were molecularly confirmed as B. truncatus, three as B. forskalii and four as B. globosus. The remaining samples were morphologically identified as B. truncatus (n = 49) and B. forskalii (n = 2). The microsatellite analysis of 1124 cercariae revealed 186 cercarial multilocus genotypes (MLGs). Identical cercarial genotypes were frequently (60%) identified from the same snail (clonal populations from a single miracidia); however, several (40%) of the snails had cercariae of different genotypes (2–10 MLG’s) indicating multiple miracidial infections. Fifty-seven of the B. truncatus and all of the B. forskalii and B. globosus were shedding the Bovid schistosome S. bovis. The other B. truncatus were shedding the human schistosomes, S. haematobium (n = 6) and the S. haematobium group hybrids (n = 13). Two B. truncatus had co-infections with S. haematobium and S. haematobium group hybrids whilst no co-infections with S. bovis were observed. Conclusions This study has advanced our understanding of human and bovid schistosomiasis transmission in the Niger River Valley region. Human Schistosoma species/forms (S. haematobium and S. haematobium hybrids) were found transmitted only in five villages whereas those causing veterinary schistosomiasis (S. bovis), were found in most villages. Bulinus truncatus was most abundant, transmitting all Schistosoma species, while the less abundant B. forskalii and B. globosus, only transmitted S. bovis. Our data suggest that species-specific biological traits may exist in relation to co-infections, snail-schistosome compatibility and intramolluscan schistosome development.

11 páginas, 1 tablas, 6 figuras, Schistosomiasis is considered a neglected parasitic disease. Around 280,000 people die from it annually, and more than 779 million people are at risk of getting infected. The schistosome species which infect human beings are Schistosoma mansoni, Schistosoma haematobium, Schistosoma intercalatum, Schistosoma japonicum, Schistosoma guineensis, and Schistosoma mekongi. This disease is also of veterinary significance; the most important species being Schistosoma bovis since it causes the disease in around 160 million livestock in Africa and Asia. This work was aimed at designing and developing a genus-specific loop-mediated isothermal amplification (LAMP) method for detecting the most important schistosome species affecting humans and for the species-specific detection of S. bovis. Bioinformatics tools were used for primer design, and the LAMP method was standardised for detecting the ITS-1 region from S. intercalatum, S. haematobium, S. mansoni, S. japonicum, and S. bovis DNA (generic test) and the NADH 1 gene for specifically detecting S. bovis (at different DNA concentrations). Detection limits achieved were 1 pg DNA for S. mansoni, 0.1 pg for S. haematobium, 1 pg for S. intercalatum, and 10 pg for S. bovis. No amplification for S. japonicum DNA was obtained. The LAMP designed for the amplification of S. bovis NADH-1 worked specifically for this species, and no other DNA from other schistosome species included in the study was amplified. Two highly sensitive LAMP methods for detecting different Schistosoma species important for human and veterinary health were standardised. These methods could be very useful for the diagnosis and surveillance of schistosome infections., This work was funded by the Institute of Health Carlos III, ISCIII, Spain (http:// www.isciii.es), grants: RICET RD16/0027/0018 (AMA), PI19/01727 (PFS), PI-0001-2019 Junta de Andalucía (AMA, PFS), European Union cofinancing by FEDER (Fondo Europeo de Desarrollo Regional) “Una manera de hacer Europa” and by the Plan TCUE 2018–2020 European Union cofinancing by FEDER and the Junta de Castilla y León.

Since the construction of the Diama Dam (1985), the epidemiology of schistosomiasis along the Senegal River Basin (SRB) has been extremely dynamic with outbreaks of both intestinal and urogenital schistosomiasis. In the early 2000s, technicians reported cases of suspected urogenital schistosomiasis in adults from the local hospital in Richard-Toll, Lower SRB. The genetic analysis of schistosome miracidia isolated from 11 patients in 2012 from two neighbourhoods (Campement and Gaya) of Richard-Toll confirmed infection with Schistosoma haematobium but also S. haematobium/S. bovis hybrids. Thirty-seven per cent of the miracidia were S. bovis/S. haematobium hybrids and 63% were pure S. haematobium. The data are discussed in relation to the ongoing dynamic epidemiology of the schistosomes in Senegal and the need to treat non-target individuals.

The causative agent of urogenital schistosomiasis, Schistosoma haematobium, was thought to be the only schistosome species transmitted through Bulinus snails on Unguja and Pemba Island (Zanzibar, United Republic of Tanzania). For insights into the environmental risk of S. haematobium transmission on Pemba Island, malacological surveys collecting Bulinus globosus and B. nasutus, two closely related potential intermediate hosts of S. haematobium were conducted across the island in November 2016. Of 1317 B. globosus/B. nasutus collected, seven B. globosus, identified through sequencing a DNA region of the mitochondrial cytochrome oxidase subunit 1 (cox1), were observed with patent infections assumed to be S. haematobium. However, when the collected cercariae were identified through sequencing a region of the cox1 and the nuclear internal transcribed spacer (ITS1 + 2), schistosomes from five of these B. globosus collected from a single locality were in fact S. bovis. The identified presence of S. bovis raises concerns for animal health on Pemba, and complicates future transmission monitoring of S. haematobium. These results show the pertinence for not only sensitive, but also species-specific markers to be used when identifying cercariae during transmission monitoring, and also provide the first molecular confirmation for B. globosus transmitting S. bovis in East Africa.

Background Schistosoma haematobium is the causative agent of human urogenital schistosomiasis affecting ~112 million people in Africa and the Middle East. The parasite is transmitted by snails of the genus Bulinus, which also transmit other closely related human and animal schistosomes. The accurate discrimination of S. haematobium from species infecting animals will aid effective control and elimination programs. Previously we have shown the utility of different repetitive nuclear DNA sequences (DraI, sh73bp, and sh77bp) for the identification of S. haematobium-group species and inter-repeat sequences for discriminating S. haematobium from S. bovis. Results In this current study we clarify the structural arrangement and association between the three repetitive sequences (DraI, sh73bp, and sh77bp) in both S. haematobium and S. bovis, with a unique repeat linker being found in S. haematobium (Sh64bp repeat linker) and in S. bovis (Sb30bp repeat linker). Sequence data showed that the 3′-end of the repeat linker was connected to the DraI repetitive sequence array, and at the 5′-end of the repeat linker sh73bp and sh77bp were arranged in an alternating manner. Species-specific oligonucleotides were designed targeting the species-specific repeat linkers and used in a reverse line blot (RLB) hybridization assay enabling differentiation between S. haematobium and S. bovis. The assay was used to discriminate natural infections in wild caught Bulinus globosus. Conclusion This research enabled the characterisation of species-specific DNA regions that enabled the design of species-specific oligonucleotides that can be used to rapidly differentiate between S. haematobium and S. bovis and also have the potential to aid the detection of natural hybridization between these two species.

16 páginas, 1 tabla, 3 figuras., Mesenteric infection by the parasitic blood fluke Schistosoma bovis is a common veterinary problem in Africa and the Middle East and occasionally in the Mediterranean Region. The species also has the ability to form interspecific hybrids with the human parasite S. haematobium with natural hybridisation observed in West Africa, presenting possible zoonotic transmission. Additionally, this exchange of alleles between species may dramatically influence disease dynamics and parasite evolution. We have generated a 374 Mb assembly of the S. bovis genome using Illumina and PacBio-based technologies. Despite infecting different hosts and organs, the genome sequences of S. bovis and S. haematobium appeared strikingly similar with 97% sequence identity. The two species share 98% of protein-coding genes, with an average sequence identity of 97.3% at the amino acid level. Genome comparison identified large continuous parts of the genome (up to several 100 kb) showing almost 100% sequence identity between S. bovis and S. haematobium. It is unlikely that this is a result of genome conservation and provides further evidence of natural interspecific hybridization between S. bovis and S. haematobium. Our results suggest that foreign DNA obtained by interspecific hybridization was maintained in the population through multiple meiosis cycles and that hybrids were sexually reproductive, producing viable offspring. The S. bovis genome assembly forms a highly valuable resource for studying schistosome evolution and exploring genetic regions that are associated with species-specific phenotypic traits., This work was supported by grants from the QIMR Berghofer Medical Research Institute (Chenhall Estate) and the Australian Infectious Diseases Research Centre. NDY was supported by a National Health and Medical Research Council (NHMRC) CDF1, PKK by an NHMRC ECRF and DPM by an NHMRC SPRF (APP1102926). The work has been supported by NHMRC project grant APP1102322.

Ten Belgian travelers returned from Mali with a Schistosoma haematobium-Schistosoma bovis hybrid infection, confirmed by DNA sequencing from eggs. Clinical symptoms and laboratory findings resembled those of classic acute schistosomiasis, but the detected eggs were morphologically unusual.

Background Schistosomiasis is neglected tropical parasitic disease affecting both humans and animals. Due to the human health impact, population genetic studies have focused on the three main human-infecting schistosome species: Schistosoma mansoni, S. haematobium and S. japonicum. Here we present novel data on the population genetic structure of Schistosoma bovis, a highly widespread and prevalent schistosome infecting ruminants, and therefore of veterinary importance. Methods Adult S. bovis were sampled in the two main abattoirs of Cameroon (Yaoundé and Douala). Twenty-two cows originating from four distinct localities were sampled and a total of 218 parasites were recovered. All parasites were genotyped using a panel of 14 microsatellite markers and a sub-sample of 91 parasites were sequenced and characterized with the mitochondrial (cox1) and nuclear (ITS) genetic markers. Results No significant difference in allelic richness, heterozygosity, nucleotide diversity and haplotype diversity was observed between the populations. Additionally, no strong genetic structure was observed at the country scale. Our data also show that S. bovis is more polymorphic than its sister species, S. haematobium, and that the haplotype diversity is similar to that of S. mansoni while the nucleotide diversity does not significantly differ from that of S. haematobium. The resulting negative Tajima’s D* and Fu and Li’s D* indices could be a signature of population demographic expansion. No S. haematobium/S. bovis hybrids were observed in our populations, thus all samples were considered as pure S. bovis. Conclusions This study provides novel insights into genetic diversity and population genetic structure of S. bovis. No strong genetic structure was observed at the country scale but some genetic indices could be associated as a signature of population demographic expansion. Electronic supplementary material The online version of this article (10.1186/s13071-019-3307-0) contains supplementary material, which is available to authorized users.

36 páginas, 5 figuras, 2 tablas. -- The definitive version is available at http://www.elsevier.com. -- The authors are grateful to Rocío Vizcaíno Marín, from the Instituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA, CSIC) (Spain), for her skillful technical assistance, and to Dr. Luz Valero, from the Proteomics Unit of the University of Valencia (Spain), for her assistance in the MS analyses., Schistosomiasis is a disease caused by blood trematodes affecting man and animals that represents an important human health and veterinary problem. Main damages caused by this infection are a consequence of the host inflammatory reaction against the parasite eggs trapped inside the liver. Despite the hepatic pathology of schistosomiasis is very well known, there is no specific studies dealing with the schistosome infection effects on the biliary function. The purpose of this work was to analyse the changes induced by Schistosoma bovis infection in the biliary proteome. For this, whole gallbladders from S. bovis-infected and non-infected mice were dissected, homogenized and fractionated by differential centrifugation. The resulting protein fractions were resolved by SDS-PAGE, the gels were sliced, and the gel pieces analyzed by LC-MS/MS. Altogether, we identified 1,937 proteins, which were classified according to their “protein class” and “molecular function”, and then subjected to an“Enrichment analysis”. The differences found in gallbladder proteomes between S. bovis-infected and non-infected mice are analysed. We show that chronic schistosome infections cause significant changes in the biliary proteome that may produce physiological alterations and affect the therapeutic actions of drugs when administered to human patients and animals with schistosomiasis, This research was funded by project AGL2010-18163 granted by the Spanish Ministry of Science and Innovation

Schistosoma bovis is a parasite of ruminants that causes significant economic losses to farmers throughout Africa, Southwestern Asia and the Mediterranean. Additionally, recent studies have reported its zoonotic potential through the formation of S. bovis×Schistosoma haematobium hybrids. As observed in the Schistosoma species infecting humans, it is assumed that S. bovis has also evolved host regulatory molecules that ensure its long-term survival in the bloodstream of its host. Since these molecules could be potential targets for the development of new drugs and anti-schistosome vaccines, their identification and functional characterization were undertaken. With this aim in mind, the molecular interface between S. bovis and its vertebrate host was subjected to a series of proteomic studies, which started with the analysis of the proteomes of the S. bovis moieties exposed to the host, namely, the excretory/secretory products and the tegument surface. Thus, a wealth of novel molecular information of S. bovis was obtained, which in turn allowed the identification of several parasite proteins with fibrinolytic and anticoagulant activities that could be used by S. bovis to regulate the host defensive systems. Following on, the host interface was investigated by studying the proteome of the host vascular endothelium surface at two points along the infection: in the lung vessels during the schistosomula migration and in the portal vein after the parasites have reached adulthood and sexual maturity. These studies have provided original data regarding the proteomes of the endothelial cell surface of pulmonary vasculature and portal vein in S. bovis-infected animals, and have shown significant changes in these proteomes associated with infection. This review compiles current information and the analyses of all the proteomic data from S. bovis and the S. bovis-host interface, including the molecular and functional characterization of S. bovis proteins that were found to participate in the regulation of the host coagulation and fibrinolysis systems.

A 12-year-old male patient suffered hematuria. Histopathology of a biopsy showed granulomata suspicious for schistosomiasis. The patient had never travelled outside Europe during his entire lifetime. He had taken frequent bathes in various rivers during his last family holidays 5 months earlier in Corsica. Microfiltration of urine revealed viable ova of Schistosoma haematobium with alterated size and shape. Ultrasonography showed a large focal echopoor mass attached to the bladder roof. Four days after antihelminthic therapy, the patient suffered inferior abdominal pain and acute anuria. Ultrasound revealed an approximately 5-cm mass in the bladder lumen suspicious for a large blood clot. After taking non-invasive measures such as drinking high amounts of fluid and treating the lower abdomen with a warm water bag and massage, the clot was excreted with urine and symptoms subsided. The further course was uneventful until 11 months later when hematuria recurred. This time, parasitological urine examination confirmed non-viable schistosome ova. Hematuria was likely due to erosion of the bladder mucosa by calcified non-viable ova.

Schistosoma haematobium and S. bovis are widespread schistosome species causing human and cattle schistosomiasis, respectively, in Africa. The sympatric occurrence of these two species and their ability to infect the same Bulinus intermediate snail hosts necessitates precise methods of identification of the larval stages. A rapid diagnostic ‘mulitplex’ one-step polymerase chain reaction protocol (RD-PCR) was developed using cytochrome oxidase subunit 1 (COX1) mitochondrial DNA (mtDNA) to discriminate between S. haematobium and S. bovis. A single forward primer and two species-specific reverse primers were used to produce a polymerase chain reaction (PCR) fragment of 306 bp and 543 bp for S. bovis and S. haematobium, respectively. Serial dilutions were carried out on various lifecycle stages and species combinations to test the sensitivity and specificity of the primers. This RD-PCR proved highly sensitive, detecting a single larval stage and as little as 0.78 ng of genomic DNA (gDNA) from an adult schistosome, providing a cost-effective, rapid and robust molecular tool for high-throughput screening of S. haematobium and S. bovis populations. In areas where human and cattle schistosomiasis overlap and are transmitted in close proximity, this mitochondrial assay will be a valuable identification tool for epidemiological studies, especially when used in conjunction with other nuclear diagnostic markers.

Currently available candidate vaccines against schistosomiasis elicit only partial protection. In addition, the type of immune response that could lead to the highest level of protection against schistosomes has not yet been described. Thus, efforts should be made in both the identification of novel proteins essential for the parasite cycle and in the modulation of immune responses against these novel candidates through the combined use of immunomodulatory molecules. Several parasites have 14-3-3 proteins, and these proteins are known to play a key role in parasite biology. In the present work, we report the isolation and characterization of a new 14-3-3 gene from Schistosoma bovis and offer new information regarding the genetic structure of the gene. In addition, we have produced the corresponding recombinant protein. Finally, we describe the immune responses elicited by this protein when combined with 4 different immunomodulators in immunized mice.

International audience; This study concerns the first urinary schistosomiasis case observed in Corsica (France, Europe) occurring in a 12-year-old German boy. The aim was to identify the relationship between this Schistosoma haematobium infection and other schistosomes of the Schistosoma group with terminal-spined ova. Morphological and molecular analyses were conducted on the ova. The results showed that the schistosome responsible for the emergence of schistosomiasis in Corsica was due to S. haematobium introgressed by genes from S. bovis.

Schistosoma bovis is a ruminant pathogen that is poorly known at a molecular level. With an aim of identifying the parasite proteins involved in host-parasite interplay, we studied two protein extracts that contain, respectively, the proteins excreted/secreted by the adult worm (ES) and the tegumental proteins exposed to the host (TG). The 2-DE, 2-D immunoblot and MS were employed to separate and identify the antigenic proteins and the most abundant non-antigenic proteins in each extract. There were some 400 and 600 spots detected in the ES and the TG extracts, respectively. Ninety-six spots were subjected to MS analysis and 64 of them were identified. Overall, we identified 18 S. bovis proteins located at the host-parasite interface, 16 of which have not been identified previously in this parasite, and one of which -lysozyme- has never been reported in a Schistosoma species. Of the proteins identified, at least 4 can counteract host defence mechanisms. The other proteins are also likely to play some role in the host-parasite relationships. Therefore, studies in grater depth on all these proteins will provide a better understanding of how this parasite interacts with its host and new strategies for anti-schistosome drug or vaccine design.

International audience; A 12 year-old boy in Germany developed urinary schistosomiasis in January 2014. He had bathed in rivers in south-eastern Corsica five months earlier. Before this case, human schistomiasis had not been reported on the island, although its vector, the snail Bulinus truncatus, locally transmitted the zoonotic Schistosoma bovis. The boy's father excreted S. haematobium ova that were not viable; the boy's three siblings had a positive serology against schistosomes.

46 páginas, 6 figuras, 3 tablas.--The definitive version is available at http://www.elsevier.com, Schistosomes are blood trematodes that are perfectly adapted to living in their intravascular habitat and to achieve this they have developed mechanisms enabling them to evade the immune and haemostatic responses of the host and to regulate endothelial cell function to favour their own survival. The objective of this work was to analyse the changes induced by Schistosoma bovis schistosomula in the proteome expressed by infected hamsters, over 10 and 20 days, on the endothelial surface of their pulmonary vasculature. To accomplish this, we subjected the lungs of non-infected and S. bovis-infected hamsters to vascular perfusion with a biotin ester reactive. Analysis by liquid chromatography and tandem mass spectrometry analysis (LC–MS/MS) of endothelial surface proteins resulted in the identification of a total of 459 non-redundant proteins in the lung vasculature of infected and non-infected hamsters. Here we report the proteins identified, classified according to their biological function and cellular location, further analysing the differences in lung vascular proteomes between non-infected and S. bovis-infected hamsters for ten and twenty days. This work provides the first data on the vascular surface proteome of the lung after S. bovis infection and identifies some of the changes induced in it during infection., This research was funded by project AGL2010- 597 18163 granted by the Spanish Ministry of Science and Innovation.

30 páginas, 3 figuras, 1 resumen gráfico, 3 tablas. -- The definitive version is available at http://www.elsevier.com, Schistosoma bovis is a blood-dwelling fluke of ruminants that lives for years inside the vasculature of their hosts. The parasite tegument covers the surface of the worms and plays a key role in the host–parasite relationship. The parasite molecules expressed at the tegument surface are potential targets for immune or drug intervention. The purpose of this work was the identification of the proteins expressed in vivo on the surface of the tegument of S. bovis adult worms. To accomplish this we used a method based on in vivo vascular perfusion of mice infected with S. bovis which allowed the labelling of the surface of the worms inside the blood vasculature. The biotinylation of parasite inside blood vessels prevents the handling of worms in vitro and hence possible damage to the tegument that could produce results that would be difficult to interpret. Trypsin digestion of biotinylated proteins and subsequent liquid chromatography and tandem mass spectrometry analysis (LC–MS/MS) resulted in the identification on the S. bovis tegument of 80 parasite proteins and 28 host proteins. The proteins identified were compared with the findings from other proteomic studies of the schistosome surface. The experimental approach used in this work is a reliable method for selective investigation of the surface of the worms and provides valuable information about the exposed protein repertoire of the tegument of S. bovis in the environmental conditions that the parasite faces inside the blood vessels., This research was funded by project AGL2010-18163 granted by the Spanish Ministry of Science and Innovation.

Detection of circulating Fasciola gigantica antigen was performed in sera of sheep with experimental and natural F. gigantica infections using the direct enzyme-linked immunosorbent assay method. Sera from sheep with monoinfections of Schistosoma bovis, Dicrocoelium hospes and Paramphistomum microbothrium were included in the assay to ascertain specificity. Circulating F. gigantica antigen (CFA) was detected as early as 1 week after infection in the experimentally infected sheep. No detectable CFA was observed 2 weeks after chemotherapy. Positivity rates of 82.5%, 12.5%, 10% and 10% were found in sera with monospecific infections of F. gigantica, P. microbrothrium, D. hospes and S. bovis, respectively. Acid treatment of the sera did not enhance the sensitivity of the assay.

Experimental Schistosoma bovis infections were studied in groups of six goats for 32 weeks. Two types of primary infections, a single exposure to 400 cercariae per goat or repeated (trickle) exposure to 200 cercariae per goat weekly for 10 weeks, were followed by a challenge infection with 2000 cercariae per goat in week 16 of the experiment. Periods of high faecal egg excretion were associated with reduced weight gain, anaemia, hypoalbuminaemia and blood eosinophilia; these changes gradually diminished with decreasing faecal egg excretion but never disappeared completely. The pathogenic effects of the trickle exposure exceeded those of the single primary exposure. After the challenge, the goats excreted few or no additional eggs and no additional clinicopathological changes were observed in the group previously exposed to a trickle infection. However, the primary single infection did not provide full protection against the effects of the challenge infection.

23 páginas, 3 tablas, 4 figuras, 1 resumen gráfico. -- The definitive version is available at http://www.elsevier.com, Schistosomes are blood parasites adapted to their intravascular habitat that have evolved mechanisms to evade the immune and hemostatic responses of their hosts. It has been observed that the schistosome can regulate the endothelium function along the infection, which contributes to modulation of host defensive responses and parasite survival. The purpose of this work was the analysis of the changes induced by Schistosoma bovis adult worms in the proteome expressed by infected mice on the endothelial surface of their portal vein. With this aim, we have utilized a methodology that allows the purification, identification and relative quantification of endothelial cell surface proteins after their selective in vivo labeling with biotin. Trypsin digestion of the biotinylated proteins and subsequent liquid chromatography and tandem mass spectrometry analysis (LC–MS/MS) resulted in the identification of a total 127 non‐redundant proteins. All these proteins have been classified according to their function and cellular location, and the differences between S. bovis-infected and non-infected mice in their endothelial surface proteomes have been analyzed. The present work provides the first data on the proteome of the endothelial surface of the portal vein, and identifies some of the changes induced in it after an infection by S. bovis., This research was funded by project AGL2010-18163 granted by the Spanish Ministry of Science and Innovation. E. De la Torre-Escudero is a holder of a predoctoral fellowship from the Ministry of Science and Innovation. R. Manzano-Román was funded by the JAEDoc program (CSIC-FSE).

27 páginas, 7 figuras. -- The definitive version is available at http://www.elsevier.com, Animal schistosomiasis caused by Schistosoma bovis is a veterinary problem in many areas of the world. It affects a large number of animals and causes important economic losses in livestock production. The 22.6 kDa antigen is a tegumental protein of unknown function, restricted to schistosomes. In S. bovis it has been identified in the tegument and in an excretion–secretion extract, consisting of several, non-glycosylated isoforms that are recognised by the sera of animals infected with S. bovis. The aims of the present work were to clone, sequence, express and characterize at molecular level the S. bovis 22.6 antigen (Sb22.6), as well as to assess the usefulness of the corresponding recombinant protein as a diagnostic antigen in ELISA tests for the detection of free-range cattle farms infested with S. bovis. Immunolocalization studies revealed that Sb22.6 is expressed in the tegument and some internal tissues of the adult worms, but it is not exposed on the surface of the adult worms and schistosomula. The reactivity of the recombinant Sb22.6 (rSb22.6) in ELISA against antibodies in sera from S. bovis experimentally infected hamsters and sera from free-range cattle from a S. bovis endemic area showed that the recombinant protein and the soluble extract of adult worms (SbC) exhibited a similar diagnostic performance. In addition, rSb22.6 did not show cross-reactions with antibodies against Fasciola hepatica, also a frequent trematode parasite in cattle. The rSb22.6 antigen can be readily produced in large amounts and in a highly reproducible fashion, avoiding the types of problem that arise upon using crude extracts such as the SbC. In conclusion, this protein represents a promising epidemiological tool for the surveillance of S. bovis and may help to implement control measures in the areas and farms were the parasite is present., This research was funded by projects AGL2007-60413 and AGL2010-18163, granted by the Spanish Ministry of Science and Innovation. E. De la Torre-Escudero is a holder of a predoctoral fellowship from the Ministry of Science and Innovation. R. Manzano-Román was funded by the JAEDoc program (CSIC-FSE).

31 páginas, 7 figuras. -- The definitive version is available at http://www.elsevier.com, Annexins belong to an evolutionarily conserved multigene family of proteins expressed throughout the animal and plant kingdoms. Although they are soluble cytosolic proteins that lack signal sequences, they have also been detected in extracellular fluids and have been associated with cell surface membranes, where they could be involved in anti-haemostatic and anti-inflammatory functions. Schistosome annexins have been identified on the parasite’s tegument surface and excretory/secretory products, but their functions are still unknown. Here we report the cloning, sequencing, in silico analysis, and functional characterization of a Schistosoma bovis annexin. The predicted protein has typical annexin secondary and tertiary structures. Bioassays with the recombinant protein revealed that the protein is biologically active in vitro, showing fibrinolytic and anticoagulant properties. Finally, the expression of the native protein on the tegument surface of S. bovis schistosomula and adult worms is demonstrated, revealing the possibility of exposure to the host’s immune system and thus offering a potential vaccine target for the control of schistosomiasis in ruminants., This research was funded by project AGL2007-60413/GAN, granted by the 562 Spanish Ministry of Science and Innovation. E. De la Torre-Escudero is holder of a 563 Ministry of Science and Innovation predoctoral grant and R. Manzano-Román is funded 564 by the JAEDoc program (CSIC-FSE).

Mouse infection models are described that demonstrate reduction of egg production in Schistosoma haematobium infections and both worm loss and reduced fecundity in S. bovis infections. Neither phenomenum could be shown in S. mansoni infected mice. The immunological basis for these anti-adult responses was inferred by comparison with infections in T-cell deprived mice and by the serum transfer of the ability to reduce a S. bovis worm burden into immunocompromised hosts. Vaccination with irradiation attenuated parasites was also shown to have consequences for the adults of a challenge infections of S. haematobium and S. bovis specifically. Prior vaccination resulted in an abrogation of the anti-fecundity and adult worm elimination that occurred in non-vaccinated similary infected mice. hese models are being used to define the targets and mechanisms involved in anti-adult attrition. A serological assay, quantitation of a circulating antigen (CAA) has been assessed for its ability to measure worm burdens of different species of schistosome in mice. This assay will be used to question whether anti-adult immunity contributes to the pattern of infection with S. mansoni and S. haematobium in man.

12 pages, 3 figures.-- PMID: 18638509 [PubMed].-- Printed version published Oct 2008. Schistosoma bovis, a parasite of ruminants, can live for years in the bloodstream in spite of the immune response of its host. The parasite tegument covers the entire surface of theworm and plays a key role in the host–parasite relationship. The parasite molecules involvedin hostimmuneresponse evasionmechanisms must be expressed on the tegument surface and are potential targets for immune or drug intervention. The purpose of the presentworkwas to identify the tegumental proteomes of male and female S. bovisworms, in particular the proteins expressed on the outermost layers of the tegument structure. Adult worms of each sexwere treated separately with trypsin in order to digest their tegumental proteins, after which the peptides released were analysed by LC–MS/MS for identification. This experimental approach afforded valuable information about the protein composition of the tegument of adult S. bovis worms. A range of tegumental proteins was identified, most of which had not been identified previously in this species. Although an absolute purification of the proteins expressed on the outermost layers of the tegument structurewas not achieved, it is likely that present among the proteins identified are some of the molecules most closely associated with the tegument surface. Our study also suggests that theremay be differences in the protein composition of the tegument of male and female schistosomes. Finally, the presence of actin and GAPDH on the surface of male and female worms and the presence of enolase exclusively on the surface of male worms were verified by confocal microscopy. This research was supported by grant AGL2007-60413 from the Ministerio de Educación y Ciencia, Spain.

16 pages, 5 figures.-- PMID: 17055171 [PubMed].-- Available online Oct 18, 2006., Schistosoma bovis is a parasite of wild and domestic ruminants that is broadly distributed throughout many tropical and temperate regions of the old world. S. bovis causes severe health problems and significant economic losses in livestock, but in contrast to human schistosomes, S. bovis has been little investigated at a molecular level. Since schistosome glycans and glycoproteins can play important roles in the host–parasite interplay, the aims of the present work were: (i) to characterize the glycans expressed by adult S. bovis worms on their excreted/secreted (ES) and tegumental (TG) glycoproteins and (ii) to identify their carrier protein backbones by mass spectrometry. Using a panel of lectins and monoclonal and polyclonal anti-glycan antibodies, we observed: (i) the absence of sialic acid in S. bovis; (ii) the presence of complex-type N-glycans and LDN antennae on ES glycoproteins; (iii) the presence of glycans containing the Fucα1-2Galβ motif in many TG glycoproteins, and (iv) the presence of glycans containing the Fucα1-3GlcNAc motif on many ES and TG glycoproteins but, simultaneously, the absence of the F-LDN(-F) glycans from both the ES and TG glycoproteins. Interestingly, we also found the Lewis(X) and Lewis(Y) antigens co-expressed on several TG isoforms of ATP:guanidino kinase and glyceraldehyde-3-phosphate dehydrogenase. Finally, by ELISA we observed the presence of antibodies against Lewis(X), Lewis(Y) and F-LDN(-F) in the sera of sheep experimentally infected with S. bovis., We would like to thank Dr. Emilio Camafeita Fernández from the Proteomic Unit of the Centro Nacional de Investigaciones Cardiovasculares of Madrid (Spain) for his assistance in mass spectrometry analyses and N. Skinner for supervising the English version of this manuscript. This research was supported by grant AGL2003-04235 from the Ministerio de Educación y Ciencia, Spain.

9 pages, 5 figures.-- PMID: 16962583 [PubMed].-- Available online Sep 8, 2006., Schistosoma bovis is a ruminant haematic parasite that lives for years in the mesenteric vessels of the host. The aim of this work was to investigate the ability of adult S. bovis worms to interact with plasminogen, a central component in the host fibrinolytic system. Confocal microscopy analysis revealed that plasminogen bound to the tegument surface of the male—but not female—S. bovis worms and that this binding was strongly dependent on lysine residues. It was also observed that a protein extract of the worm tegument (TG) had the capacity to generate plasmin and to enhance the plasmin generation by the tissue-type plasminogen activator. Proteomic analysis of the TG extract identified 10 plasminogen-binding proteins, among which the major ones were enolase, glyceraldehyde-3-phosphate dehydrogenase and actin. This study represents the first report about the binding of plasminogen to Schistosoma sp. proteins., We thank Dr. Emilio Cervantes of the Instituto de Recursos Naturales y Agrobiología of Salamanca (CSIC) (Spain) for his assistance in performing the confocal microscope analyses; Dr. Emilio Camafeita Fernández from the Proteomic Unit of the Centro Nacional de Investigaciones Cardiovasculares of Madrid (Spain) for his assistance in MS analyses and N. Skinner for supervising the English version of this manuscript. This research was supported by Grant AGL2003-04235 from the Ministerio de Educación y Ciencia, Spain.

The aim of this study was to elucidate the regulatory responses and the long-term effect of praziquantel treatment in chronically Schistosoma bovis-infected West African Dwarf goats. Forty-two goats were used and the design comprised a primary infection followed by treatment at week 13, challenge infection at week 36 and termination at week 52. Dependent variables included clinico-pathological data, worm numbers, faecal and tissue egg counts, and gross pathology of the liver. The results showed that primary infections remained suppressed for up to 52 weeks and, although challenge infections imposed on 36-week-old primary infections established fully, the impairment of their egg production capacity provided protection against clinico-pathological consequences measured by body weight and haemoglobin levels. The study also confirmed a high efficacy (97.7%) of praziquantel for treatment of S. bovis infection in goats and showed that anthelminthic removal of primary infections does not interfere with the ability of the goat to elicit a marked resistance to a subsequent challenge infection. Although treated goats had more fibrous scarring of livers than untreated goats, no negative effects of liver lesions were reflected in weight gains of treated goats. This study provides strong evidence for the beneficial effects of anthelminthic treatment of young domestic stock as an element of treatment and preventive programmes.

The percutaneous administration of cercariae is the usual method for experimental infections with Schistosoma bovis. These procedures are laborious and have important inconveniences when working with a large number of animals, especially if they are ruminants. In the present study, the efficiency of the oral, intramuscular and subcutaneous routes are evaluated by comparison with the percutaneous route in experimental infections with S. bovis. The infections developed in hamsters and sheep were evaluated taking as a basis the parasite burden, the concentrations of eggs in tissues and the levels of anti-Schistosoma antibodies. The oral infection failed in both hamsters and sheep. The administration of the cercariae by the intramuscular route was effective in sheep, developing infections of intensity similar to that of the infections acquired percutaneously. In hamsters, on the contrary, although all the animals developed the infection, they were very little intense. The injection of the cercariae by the subcutaneous route induces acceptable infections in hamsters and can also be an alternative route to percutaneous exposure. The levels of the anti-Schistosoma bovis antibodies detected in hamster and sheep were proportional to the number of worms present, which shows that the humoral response is a good indicator of the intensity of the infections. It can be concluded that the intramuscular route is a good alternative to the percutaneous route for experimental infections of sheep with S. bovis. Likewise, the subcutaneous route can also substitute, with some advantages, the percutaneous infections in hamsters.

The effect of praziquantel against experimental Schistosoma bovis infection in West African Dwarf goats was investigated. Thirty goats were exposed to 2000 cercariae each and 15 of those received a praziquantel treatment (60 mg kg−1) 13 weeks post-infection. One day, 1 week and 4 weeks post-treatment representative goats from each group were killed and worms were recovered by perfusion. For comparison, parasite-free control animals were monitored, some of which were given praziquantel. Every second week during the study, faecal samples were collected. The cure rate was 100% 1 day, 99.4% 1 week and 95.7% 4 weeks post-treatment. Tissue egg counts were significantly reduced (P

Summary The possession of common antigens by three trematode parasites which commonly occur together in ruminants in the tropics, Fasciola gigantica, Dicrocoelium hospes and Schistosoma bovis was studied in relation to the reliability of serodiagnosis of infection with these helminths. The crude antigenic extracts of the three trematodes were subjected to Sephacryl S‐300 column chromatography and F. gigantica was fractionated into six peaks, S. bovis into nine peaks and D. hospes into seven peaks. Common antigens were found in these three trematodes in both the crude whole worm antigenic extracts and in the semi‐purified fractions obtained by Sephacryl S‐300 column chromatography. The implications of this finding and the limitation it imposes on the usefulness of serodiagnostic tests in routine use as regards their specificity are discussed in relation to previous studies.

The cercarial shedding of Schistosoma bovis and S. haematobium were studied in single and mixed infections in the snail host Bulinus truncatus. The two species displayed a distinctive diurnal cercarial emergence with an earlier shedding pattern for S. bovis than S. haematobium (the average emergence peaks were respectively at 0800 h and 1200 h). In mixed infections, each species kept its own cercarial shedding rhythm with no marked alterations. The cercarial emergence pattern is proposed as a new method to identify natural mixed infections in the snail intermediate hosts. The interactions between the two parasites are discussed.

The syringe and the modified Bell filtration techniques, the cellophane faecal thick smear (Kato/Katz) and Teesdale (sandwich) smear techniques, and the formol-ether concentration technique were compared for efficiency for detection of eggs of Schistosoma bovis in faeces from cattle and goats. Both filtration techniques were highly effective as revealed by high sensitivity and mean egg counts. However, efficiency declined markedly using formalin-fixed faecal material. The efficiency of the Teesdale technique was comparable to that of the filtration techniques, whereas the efficiency of the Kato/Katz technique in goats and the formol-ether concentration technique in cattle was markedly lower. The ease of performance combined with the high sensitivity make the syringe filtration and the Teesdale techniques recommendable for field diagnosis of schistosomiasis in domestic stock.

Cercarial production related to miracidial dose variation with Schistosoma bovis strains from Sudan and Spain in Bulinus truncatus from Tunisia was studied. Results showed that an increase in the miracidial dose proposed to the host-mollusc (1 and 5 miracidia) gave rise to a decrease in cercarial productivity of Sudanese S. bovis and to an increase for Spanish s. bovis. It is concluded that this response difference tothe miracidial dose variation depends on genetic characters peculiar to the parasite strain and represents a new aspect of genetic variability of schistosome populations.

There are two main and two weak fractions of malate dehydrogenase isoenzyme common toSchistosoma bovis, S. leiperi, S. margrebowiei andS. mattheei: a major fraction at pI 8.56, seconded at pI 7.38, with weaker activity at pI 7.05 and pI 8.15. Variation in malate dehydrogenase occurs in some species/strainsen passage.

The relationship between an isolate of Schistosoma bovis from Iringa, Tanzania, and various species of the host snail genus Bulinus from East Africa was studied using the total cercarial production per 100 exposed snails over a period of 4 weeks following patency as an index of the compatibility. All populations of Bulinus forskalii and B. africanus tested exhibited a high level of susceptibility while the populations of B. truncatus and B. globosus tested were either refractory or of low to moderately low susceptibility. All populations of B. abyssinicus, B. canescens, B. nasutus and B. tropicus tested were refractory. It is suggested that B. africanus is the most important host snail for S. bovis in East Africa, that B. forskalii at least locally may contribute significantly to the transmission and that B. truncatus and B. globosus only play a limited role in the transmission.

Epizootiological observations on Schistosoma bovis in cattle at Kosti, Sudan, showed a significant fall in age-specific prevalence and intensity with age, based on fecal egg count. To test the possibility that this is due to acquired resistance, Kosti cattle and a control group of cattle of similiar breed and age from a nonenzootic area were experimentally challenged with 70,000 S. bovis cercariae. Clinical observations showed very clearly that the Kosti cattle were able to withstand almost completely the effects of the challenge, whereas the controls developed lethal infections. Resistance was further demonstrated by clear differences between the two groups in terms of their body weights, hematological measurements, histopathological and pathophysiological responses, and worm and egg counts. The data suggested that the main basis of the resistance was a suppression of egg production by the worms from the challenge, rather than absolute prevention of their maturation. There was also evidence of a suppression of the fecundity of worms in the naturally infected Kosti cattle.

A comparative experimental study of the rhythmic shedding of two geographic strains of Schistosoma bovis cercariae by Bulinus truncatus and Planorbarius metidjensis did not show any differences in emergence patterns. In our opinion, the results support the hypothesis that cercarial emission rhythms are determined primarily by the parasite in these snail/parasite associations.

Sensitisation of goats for eight weeks with metacercariae of Fasciola gigantica gamma-irradiated at 3 kr resulted in significant resistance to an homologous challenge with normal metacercariae. However, serum sorbitol dehydrogenase assay suggested that, whereas little damage was produced by immunising infections, considerable hepatic damage was caused by flukes remaining from challenge infections. On the other hand sensitisation with cercariae of Schistosoma bovis gamma-irradiated at 3 kr did not stimulate any resistance against heterologous challenge with F. gigantica.

SUMMARYDaughter sporocysts (SpII) of Schistosoma bovis produced by the mother sporocyst (SpI) can direct their production along three different pathways during intramolluscal development. (i) Direct sporocystogenesis–tertiary sporocysts (SpIII) are directly produced by non-cercariae producing daugher sporocysts (SpIII). (ii) Simultaneous sporocystogenesis and cercariogenesis–SpIII are produced by Spil in which cercariae are being produced. (iii) Sporocystogenesis after cercariogenesis-Spill are produced by SpIl in which cercariae are undergoing degeneration. These mechanisms can be interpreted in terms of demographic strategy leading swiftly to the taking over and optimum exploitation of the host's hiotic capacity.

SummaryFourteen 9-month-old zebu calves were immunized with 10000 irradiatedSchistosoma bovisschistosomula given in 1–3 intramuscular or subcutaneous doses, and 4 more calves were immunized with 10000 irradiated cercariae administered percutaneously in a single dose. Eight weeks after the beginning of the experiment these calves, together with four non-immunized controls were challenged percutaneously with 10000 normalS. boviscercariae/calf. Comparative clinical, parasitological, pathological and pathophysiological observations subsequently revealed significant differences between the vaccinated and non-vaccinated calves. The vaccinated calves showed significantly higher growth rates, and a superior body composition as indicated by their lower total body water content. The beneficial effects of vaccination were also shown by significantly lower faecal egg outputs in the vaccinated calves and by their lower tissue egg and adult worm counts. The reduced tissue egg counts were also reflected in the milder histopathological changes seen in the vaccinated calves. The vaccinated calves had significantly higher packed cell and circulating red blood cell volumes than the challenged controls, longer red blood cell half lives, and somewhat lower blood volumes and rates of red blood cell synthesis. No untoward clinical effects that could be attributed to vaccination were recorded. These results indicate that zebu cattle can be effectively protected againstS. bovisby vaccination with irradiated organisms. We are now evaluating this type of vaccine in a field trial in an enzootic area in the Sudan.

S. bovis is an economically important parasite of cattle and possibly of sheep and other domestic stock in many African and Mediterranean countries. Control of this infection by chemotherapy and mollusciciding is impractical and this has stimulated interest in vaccination. Previous work in sheep with the Central and South African species S. mattheei has led to the development of an effective vaccine which incorporates irradiated schistosomula produced by artificial transformation of cercariae. In the present experiments a similar S. bovis vaccine has been used in sheep. Fifteen 5 month old Border Leicester × Suffolk crossbred wethers were divided into three groups, two were vaccinated with either 10000 or 20000 6 krad irradiated S. bovis schistosomula, and the third kept as unvaccinated controls. All sheep were challenged with 6700 normal S. bovis cercariae.Worm recoveries and tissue egg counts at necropsy showed that vaccination with 10000 irradiated schistosomula produced a reduction of 71% in the mean worm burden resulting from challenge of the controls and the mean densities of eggs in the tissues were reduced by 75–82%. Immunization with 20000 irradiated schistosomula was not more effective. Histopathological observations showed that both groups of vaccinated sheep had much milder lesions in the intestines than the non-vaccinated controls. There was also a clear reduction in the severity of liver lesions in 4 of the 5 sheep given the lower dose of irradiated schistosomula but the livers of sheep vaccinated with 20000 irradiated schistosomula had severe and widespread lesions due mainly to a massive accumulation of eosinophils and other inflammatory cells around the vessels.

Five desert sheep were exposed to 5000 or 10000Schistosoma boviscercariae each, and the parasitological, clinical and pathological parameters were recorded. The pre-patent period was approximately 7 weeks and from that time onwards, the animals became progressively ill and emaciated. Following necropsy at the 12th week, a percentage schistosome recovery ranging from 36%—63.6% was found, and there were high egg densities in the intestinal tract and the liver. These organs revealed severe pathological lesions which were described in detail along with the changes occurring in other tissues.

A Sudanese isolate of Schistosoma bovis from experimentally infected sheep was found to be highly pathogenic to albino mice. Eggs were first found in the livers 42 days after exposure. The distribution of eggs in the liver and small and large intestines changed little during the course of infection. Results arc compared with others using an Iranian isolate of S. bovis, which causes only a mild infection, and S. mattheci.

(1969). Studies on bovine schistosomiasis in the Sudan. Annals of Tropical Medicine & Parasitology: Vol. 63, No. 4, pp. 501-513.