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Non-parasitic vermiform organisms can circumstantially be associated with humans and their identification can be challenging for medical professionals. The present report describes the finding of a worm in the toilet bowl by a patient from Brazil, who thought he had expelled it in his feces. The gross analyses in a clinical laboratory reveal the worm was different from other macroscopic organisms routinely identified, and the laboratory staff requested assistance in an academic laboratory specialized in helminthology. After preliminary analysis in a stereomicroscope, the supposed human worm was identified as an oligochaete annelid (earthworm). The patient was contacted to investigate a possible case of pseudoparasitism. However, we were informed that the organism had been collected in a toilet bowl from a rural environment where the untreated water comes from a cistern indicating our finding was circumstantial. The methodology revisited herein allowed a quick microscopic analysis of easy-to-view morphological structures, which are useful to separate oligochaete annelids from helminths and can prevent misdiagnosis in similar situations. We discuss the overly restricted view on human parasites by health professionals in collecting clinical history and laboratory analysis, providing some epistemological insights on the necessary interdisciplinarity between parasitology and other basic knowledge with health practice.

The schistosome oviposition and granuloma constitution in the peritoneal cavity of AKR/J mice were evaluated. Groups of mice intraperitoneally infected with cercariae of Schistosoma mansoni were weekly euthanized during the acute (56 to 84 days post-infection (DPI)) and chronic (147 to 175 DPI) phase of infection. Schistosome developmental stages obtained via peritoneal lavage and perfusion of the portal system were inspected, counted and fixed, and peritoneal granulomata were then processed for histology. The morphological characterization and quantitative analysis of peritoneal schistosome eggs and granulomata were for the first time performed, such as the demonstration of the viability of miracidia obtained there from. Eutopic and ectopic mature schistosomes and normal pattern of worm oviposition were observed in all periods studied. However, the size of schistosome eggs from peritoneal cavity was smaller than observed for eggs laid by female worms from the portal system. The numbers of S. mansoni eggs and/or granulomata recovered from the peritoneal cavity was higher in chronic than acute infection, while the mean diameter of peritoneal chronic granulomata was smaller than for peritoneal acute granulomata. The constitution and evolution of these cellular reactions at histology were similar to that of hepatic granuloma, and peritoneal granulomata were subject to the host immunomodulation. In addition to the standardization of this experimental approach, which allows the obtaining of free schistosomal granulomata from peritoneal cavity of AKR/J mice, the potential use of these granulomata in ex vivo and in vivo studies is discussed.

The trematodes belonging to the genus Platynosomum are biliary parasites of birds and mammals (domestic and wildlife) in tropical and subtropical areas of the globe. Despite several reports on platynosomosis in captive nonhuman primates, mainly in South America, the taxonomy of species of Platynosomum that infect these hosts remains confused, and it is not clear whether the species found in cats is the same that infects nonhuman primates. Because a detailed morphological study of Platynosomum from nonhuman primates is lacking, in this study we analyzed specimens of Platynosomum recovered from the biliary system of Callithrix penicillata kept in captivity in an animal facility. The helminths were submitted to morphological and morphometric analyses in a light microscope and measurements of 16 morphological traits were taken. A kernel density estimation (KDE) was used to estimate density distributions of the measurements obtained as well as the occurrence of overlap with the ranges of the measurements known to 2 other species of Platynosomum previously described from South American marmosets, Platynosomum amazonensis and Platynosomum marmoseti. A principal component analysis (PCA) was also performed in order to evaluate the position of each of the 3 species in the multivariate gradient of morphometric measurements. The occurrence of a growth gradient was also evaluated by analysis of correlation between the measurements. Besides a great morphological variability, all specimens obtained from marmosets in this study were identified as Platynosomum illiciens (Braun, 1901). In addition, the published ranges of the measurements of P. amazonensis and P. marmoseti were completely contained within the ranges found in this study as revealed by KDE. The PCA did not show the formation of groups, and the 3 species were distributed along a growth continuum, also corroborated by correlation analysis. Therefore, P. amazonensis and P. marmoseti are here synonymized with P. illiciens. The involvement of wildlife hosts to the epidemiology of feline platynosomosis and implications for its control are briefly discussed.

The importance of platynosomiasis has increased in feline veterinary practice, but aspects related to the specificity of Platynosomum spp. in definitive hosts requires further study. Although morphological traits suggest that the same species, P. illiciens, may infect both birds and mammals, the synonymies previously proposed have not been widely accepted, likely because host specificity is assumed. In addition, the name P. fastosum has frequently been used for parasites recovered from mammals. In the present study, metacercariae (n= 100/animal) of P. illiciens recovered from lizards (Hemidactylus mabouia) in Brazil were fed to Australian parakeets (Melopsittacus undulatus) and mice. Two parasites were recovered from the liver of one M. undulatus specimen during a necropsy that was performed 105 days after infection, and all mice were found to be infected with 37 ± 12 (18-48) parasites. The morphology of the P. illiciens obtained from the parakeet was similar to that of parasites obtained from mice and those described previously from naturally infected birds and mammals. Non-specificity of P. illiciens in hosts is discussed briefly, based on the parasitological and morphological results obtained during the avian experimental platynosomiasis and the epidemiology and geographical distribution of this parasite.

The aim was to correlate the gastrointestinal transit profile in rats, evaluated by a biomagnetic technique, in response to infection with different loads of Strongyloides venezuelensis. Eggs per gram, intestinal number of worms and fecundity, and also gastric emptying time, cecum arrival time, small intestinal transit time and stool weight were determined. Assessments occurred at 0 (control), 3, 6, 9, 12, 15, 18 and 21 days post infection (dpi) with three infective loads (400, 2000, and 10,000 L). Gastric emptying was faster (p=0.0001) and the intestinal transit was significantly slower (p=0.001) during the infection time course. Also, linear mixed-effects models showed significantly changes in small intestinal transit after three parasite load over time. Cecum arrival was not influenced by infection time course or parasite load. As indirect effect, stool weight decreased accompanied a strong oviposition peak at 9 dpi in 400 L and 2000 L. In several motor function instances, neuromuscular dysfunction persists after mucosal inflammation has decreased. Our approach could be very helpful to evaluate gastrointestinal motor abnormalities in vivo after parasite infection. Despite parasitological data progressively decreased after 15 dpi, small intestinal transit worse over time and according to burden., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Centrocestus formosanus is an intestinal foodborne trematode with medical and veterinary importance that remains with the pathological and immunological aspects of the infection in definitive host poorly studied. In the present study, we evaluated the effects of pharmacological immunosuppression by glucocorticoids in experimental centrocestiasis. Mice of the AKR/J strain were orally inoculated with 100 metacercariae of C. formosanus obtained in naturally infected fish (Australoheros facetus) collected in an urban reservoir from Brazil. Treatment with dexamethasone (25 mg/kg, via subcutaneous injection) was started 1h before infection of mice and then continued daily during 14 days post-infection. Untreated mice also infected with C. formosanus were used as control. At the end of the treatment course, all rodents were euthanized and adult parasites recovered from host intestines were subjected to morphological and morphometric analysis under optical microscopy. The worm burden in dexamethasone treated group [70±14 (41-85)] was significantly greater (p<0.0001) than that in the control group [15±4 (10-22)]. In addition, the parasites recovered from immunosuppressed mice were larger, with more developed reproductive structures and greater number of intrauterine eggs than in control mice. These parasite developmental changes induced by dexamethasone treatment are reported for the first time in experimental centrocestiasis. Moreover the higher parasite fecundity induced by glucocorticoid treatment had so far not been reported for any heterophyid species, which can have implications for the pathology and morbidity in infections caused by these parasites., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Despite the veterinary importance of species of Platynosomum, biliary trematode parasites of birds and mammals with worldwide distribution and a growing role in feline practice, the basic parasitological aspects of platynosomosis is still not completely understood due to the scarcity of studies in experimental models. In the present study, metacercariae of Platynosomum illiciens obtained from naturally infected tropical house geckos (Hemidactylus mabouia) in an urban area of Brazil were force-fed to mice of the AKR/J strain (100 metacercariae/animal). Groups of mice were euthanized at 60, 120, 160 and 240 days post-infection (DPI), and the biliary tree of the animals (intrahepatic biliary ducts, common hepatic and bile ducts, cystic duct and gallbladder) were examined for the presence of adult parasites. Recovered flukes were counted, classified by their site of origin (i.e., intrahepatic or extrahepatic biliary ducts) and morphologically analyzed under light microscope. The number of adult parasites obtained at 60, 120, 160 and 240 DPI was 22 ± 6 (16-32), 41 ± 14 (18-48), 27 ± 11 (18-40) and 20 ± 6 (13-30), respectively, and no significant differences in total worm burden at the different experimental times were observed. However, 41%, 51%, 75% and 95% of the parasites were found in the common hepatic and bile ducts at 60, 120, 160 and 240 DPI, respectively, suggesting the occurrence of parasitic migration to the extrahepatic biliary tree during infection; however, no parasites were observed in the gallbladder or cystic duct. Regarding the morphometric analysis, progressive growth of P. illiciens during the experimental time was observed, and the parasites collected from the extrahepatic bile ducts were larger than those obtained from the intrahepatic ducts at the same time of infection. Parasites obtained from the extrahepatic biliary tree of the mice at 160 DPI had similar measurements to those of parasites obtained at 240 DPI, and those measurements were equivalent to those reported for parasites from natural hosts (cats, birds and nonhuman primates). The results obtained provide new insights into the biology of P. illiciens, and the kinetics of the parasite development of this species is presented here for the first time. The potential use of mice as an experimental model for P. illiciens is presented and the implications of the results obtained in that model for feline platynosomosis are briefly discussed., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Morphometric analysis of Schistosoma mansoni male worms obtained from AKR/J and Swiss mice was carried out. Rodents infected by the intraperitoneal route with 80 cercariae of the schistosome (LE strain) were killed by cervical dislocation at 45 and 60 days post-infection and both peritoneal lavage and perfusion of the portal system were performed for the recovery of adult worms. Characteristics including total body length, the distance between oral and ventral suckers, extension of testicular mass and the number of testes were considered in the morphological analysis. Changes that occurred in S. mansoni recovered from the peritoneal cavity or from the portal system of AKR/J and Swiss mice included total body length and reproductive characteristics. Significant morphometric alterations were also observed when worms recovered from the portal system of both strains of mice were compared with the schistosomes obtained from hamsters (Mesocricetus auratus), the vertebrate host in which the LE strain had been adapted and maintained by successive passages for more than four decades. The present results reinforce the idea that S. mansoni has high plastic potential and adaptive capacity.

Platynosomiasis is a parasitic infection reported in non-human primates, including marmosets, and is frequently difficult to diagnose. In this study, the Kato-Katz method and the spontaneous sedimentation method were evaluated for their usefulness in identifying Platynosomum eggs in fecal samples from Callithrix penicillata that naturally harbor Platynosomum illiciens. Spontaneous sedimentation allowed the diagnosis of 41.7% (5/12) and 66.7% (8/12) of infected marmosets from one and three slides, respectively, prepared from the same fecal sample. The examination of a single Kato-Katz thick smear detected 83.3% (10/12) of infection cases. The analysis of feces on three different days increased the rate of diagnosis, since 75% (9/12) and 100% (12/12) of the primates with platynosomiasis were identified using serial spontaneous sedimentation (3 slides/day) and the Kato-Katz method, respectively. The mean number of Platynosomum eggs per gram of feces determined via the Kato-Katz method was 71.7 (8-240). The spontaneous sedimentation method when performed in series is acceptable for the diagnosis of platynosomiasis. However, the Kato-Katz method, which was here used for the first time to detect this infection, has a higher diagnostic sensitivity and the advantage that a quantitative analysis of the eggs released in the host feces is possible.

Background: Strongyloides stercoralis can undergo an alternative autoinfective life cycle in the host, which, in some individuals can lead to a lethal infection. However, due to a number of factors, such as, the majority of those infected are from low-income backgrounds and the limitation in experimental models for studying human S. stercoralis, strongyloidiasis remains neglected. Improved knowledge of animal models that are susceptible to this parasite is needed in order to investigate the immunological mechanisms involved during infection and in particular to further understand the natural history of the autoinfective cycle., Methods: Callithrix penicillata were inoculated subcutaneously with 100 (n = 2), 300 (n = 4) or 500 (n = 9) third-stage infective larvae (L3i) of S. stercoralis of human origin. Three marmosets received smaller inocula (i.e., one received 100 and two received 300 L3i) to ensure a greater capacity to withstand the infection after immunosuppression, which was triggered by administration of dexamethasone during early patency. Qualitative faecal analyses began at 7 days post-infection (DPI), and semi-quantitative tests were also performed for the dexamethasone-treated primates and the three matched controls. During the necropsies, specimens of S. stercoralis were recovered and tissue fragments were processed for histopathology., Results: The mean prepatency and patency periods were 16.1 ± 3.0 and 161.1 ± 72.2 DPI, respectively. The marmosets typically tolerated the infection well, but immunosuppressed individuals exhibited higher numbers of larvae in the faeces and progressive clinical deterioration with late disseminated infection. In these cases, the number of females recovered was significantly higher than the number of inoculated L3i. Large quantities of larvae were observed migrating through the host tissues, and histopathology revealed pulmonary and intestinal injuries consistent with those observed in human strongyloidiasis., Conclusions: Both complicated and uncomplicated strongyloidiasis occur in C. penicillata that is described as a susceptible small non-human primate model for S. stercoralis. This host permits the maintenance of a human strain of the parasite in the laboratory and can be useful for experimental investigations of strongyloidiasis. In parallel, we discuss data related to the autoinfective cycle that provides new insights into the biology of S. stercoralis.

Eggs of Toxocara cati were found in the feces of Didelphis albiventris from a peridomestic urban environment in Brazil. Negative fecal tests following short-term captivity of the opossums, as well as the absence of ascaridids during necropsy, suggest the occurrence of pseudoparasitism. Implications of the findings for the epidemiology of toxocariasis are discussed.

The platynosomiasis, a worldwide parasitic disease with importance for domestic cat, has an etiological agent species of trematodes of the genus Platynosomum, whose complete life cycles are not yet known. The real role of lizards in the transmission of this dicrocoeliid parasite (as obligatory intermediate or paratenic host) still needs to be defined. In the present study, oval-shaped encysted metacercariae obtained from terrestrial isopods (Oniscidea sp. and Nagurus nanus) and elongated excysted metacercariae found in biliary ducts and gallbladder of lizards (Hemidactylus mabouia) in Brazil were used for morphological characterization and experimental infection of mice. Adult parasites recovered from bile ducts and liver of mice inoculated orally with metacercariae from both hosts (isopods and lizards) were identified as Platynosomum illiciens (=Platynosomum fastosum), showing that lizards are paratenic (not obligatory) hosts involved in the life cycle of this parasite. Moreover, Subulina octona is reported as the first intermediate host of P. illiciens in South America, and terrestrial isopods are presented here as new natural second intermediate hosts of the parasite. Finally, it is pointed out that high prevalence and intensity of infection of intermediate and paratenic hosts were observed. These findings on the life cycle of P. illiciens are relevant considering that they may indicate possible control measures of platynosomiasis.

Fingerlings of Oreochromis niloticus collected in an artificial urban lake from Belo Horizonte, Minas Gerais, Brazil, were evaluated for natural infection with trematodes. Morphological taxonomic identification of four fluke species was performed in O. niloticus examined, and the total prevalence of metacercariae was 60.7% (37/61). Centrocestus formosanus, a heterophyid found in the gills, was the species with the highest prevalence and mean intensity of infection (31.1% and 3.42 (1-42), resp.), followed by the diplostomid Austrodiplostomum compactum (29.5% and 1.27 (1-2)) recovered from the eyes. Metacercariae of Drepanocephalus sp. and Ribeiroia sp., both found in the oral cavity of the fish, were verified at low prevalences (8.2% and 1.6%, resp.) and intensities of infection (only one metacercaria of each of these species per fish). These species of trematodes are reported for the first time in O. niloticus from South America. The potential of occurrence of these parasites in tilapia farming and the control strategies are briefly discussed.

Abstract :  Seven cases of parasitism by Strongyloides cebus were identified in Lagothrix cana from Brazil. Aspects of the clinical presentation, treatment, pathology, and parasitic biology of these infections are described. Moderate to severe disease was observed, requiring hospitalization of 3 primates, and diarrhea was the most common clinical sign described. One L. cana individual died, for which ulcerative enteritis was the major finding upon histopathological analysis. The use of ivermectin in these atelids was safe and effective against the parasite. Parallel attempts to experimentally infect gerbils with the parasite failed. Lagothrix cana is presented as a new host for S. cebus. The evidence that Strongyloides infections are common in nonhuman primates under free-living conditions, and even more prevalent in captive animals, likely represents a neglected problem.

Studies related to the immunobiological aspects of an Ascaris spp. infection are still scarce, especially those that aim to elucidate the early events of the immune response. In this study, we demonstrated a novel standardized method for early experimental Ascaris infection, providing additional information about the infectivity of eggs embryonated in vitro as well as the influence of host age on development of the infection. Finally, we characterised the immunopathology of early infection, focusing on the tissue and systemic cytokine profiles and the histopathology of infection in the lungs of BALB/c mice. Our results demonstrated that the highest egg infectivity occurred on the 100th and 200th days of in vitro embryonation and that 8 week-old BALB/c mice were more susceptible to infection than 16 week-old mice. Ascaris-infected mice showed an early, significant level of IL-5 production in the lungs 4 days p.i., followed by an increase in the level of neutrophils in the inflammatory infiltrate at 8 days p.i, which was correlated with the peak of larval migration in the tissue and a significant level of IL-6 production. The inflammatory infiltrate in the lungs was gradually replaced by mononuclear cells and eosinophils on the 10th and 12th days p.i., respectively, and an increase in TNF levels was observed. The downmodulation of systemic TCD4(+) cell numbers might suggest that T cell hyporesponsiveness was induced by the Ascaris spp. larvae, contributing to safeguarding parasite survival during larval migration. Taken together, the novel aspects of Ascaris infection presented here enabled a better understanding of the immunopathological events during larval migration, providing insight for further studies focused on immunisation and immunoprophylatic assays., (Copyright © 2013 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.)

Introduction: The Pampulha reservoir has long been a focus of schistosomiasis transmission in Belo Horizonte, State of Minas Gerais, Brazil. The last malacological study conducted in this urban reservoir was more than two decades ago, and thus, an update on the distribution of the species of Biomphalaria as well as new data on the presence of Schistosoma mansoni in this water body are required., Methods: The current distribution of Biomphalaria spp. in the Pampulha reservoir and their infection with S. mansoni was evaluated during 55 malacological surveys conducted between 2009 and 2012., Results: Biomphalaria straminea displayed a high population density and distribution, and 13.7% (2,233/16,235) of the specimens collected were infected with larval trematodes other than Schistosoma mansoni. Biomphalaria tenagophila and Biomphalaria glabrata, species currently presenting a restricted distribution and small populations, displayed trematode infection rates of 15.2% (98/644) and 13% (83/640), respectively. Thirteen (2%) specimens of B. glabrata were found to be infected with S. mansoni. In addition, a historical review based on previous and new data on the occurrence patterns of Biomphalaria species in this reservoir is presented., Conclusions: The results indicate that the Pampulha reservoir remains a potential focus of urban schistosomiasis in Brazil, and significant changes in the occurrence patterns of Biomphalaria species were verified.

During necropsy of a specimen of Lagothrix cana (É. Geoffroy, 1812) (Primates: Atelidae) from the Brazilian Amazon, pinworms were found in the large intestine. The intensity of infection was 64 parasites (17 males and 47 females) and there were no gross pathological changes related to parasitism. After morphological analysis the parasites were identified as Trypanoxyuris (Paraoxyuronema) lagothricis (Buckley, 1931) (Nematoda: Oxyuridae). This is the first record of this oxyurid species in primates in Brazil.

Oogram methodology permitted a direct assessment of the fecundity of Schistosoma mansoni and the passage of parasite eggs from mesenteric vessels into the intestinal lumen in AKR/J mice that had been infected via the intraperitoneal route with 60 cercariae of the trematode and later subjected to short-term subcutaneous treatments with pentoxifylline (PTX). The administration of PTX did not change oviposition kinetics, the individual fecundity of female parasites (as determined by the study of the ratio of second-stage S. mansoni eggs per g intestine/number of female parasites recovered from the portal system), nor the number of mature and dead eggs retained in the host tissue, though the drug has known immunomodulatory effects, as shown previously in experimental schistosomiasis. A better appraisal was also carried out, including the study of statistical parameters, concerning the utilization of the ratios of each stage of immature eggs (first to fourth) per g intestine/number of female worms from the portal system. The second-stage eggs had the lowest variability, confirming that the utilization of this stage as an indicator of the individual fecundity of parasite females is indeed viable. In the light of our findings, current uses of oogram methodology are discussed. Moreover, additional consideration is given to data obtained in the present study concerning intraperitoneal infection with S. mansoni cercariae in both untreated and treated mice of the AKR/J strain, such as the recovery of mature worms, eggs and free granulomas from the peritoneal cavity of these rodents.

In order to better understand the biology of Centrocestus formosanus in a definitive host model, mice of Swiss and AKR/J strains were experimentally infected with 100 metacercariae of the parasite. Fourteen days post-infection, the rodents were killed and adult trematodes were recovered from the small intestine. The percentage of parasite recovery from AKR/J mice (11.4%) was significantly higher than that from Swiss mice (5.3%). Moreover, trematodes recovered from the AKR/J strain were more developed and had greater fecundity. Peculiarities concerning the mice's immune system could explain the difference in susceptibility and in worm development seen in the present study. The data obtained confirm that mice are susceptible to infection with C. formosanus and indicate that the AKR/J strain provides a more favorable environment for parasite development.

In order to better understand experimental strongyloidiasis in small New World primates, and to evaluate aspects of reinfection and immunosuppression induced by glucocorticoids, nine specimens of Callithrix penicillata (Primates: Cebidae) were administered (by subcutaneous injection, sc) 3000 infective larvae of a strain of Strongyloides venezuelensis (Rhabditida: Strongyloididae) that had been maintained in successive passages through AKR/J mice since 1987. The mean prepatent period was 5.6 ± 0.7 days post-infection (DPI). The mean patent period of infection among the untreated animals (marmosets 1-7) was 123.4 ± 61.4 DPI. Two animals (marmosets 8 and 9) received dexamethasone (2.5 mg/kg, sc) for five consecutive days starting on the 20th day after infection, but this treatment did not alter the course of the infection, and the patent period for these animals was 100.5 ± 58.7 DPI (59 and 142, respectively). Stool examination showed that the highest quantities of parasite eggs were expelled between the 8th and 19th days after inoculation of the larvae. Thereafter, there was a gradual reduction in the number of parasite eggs in feces of all marmosets. During the chronic phase of the infection, before completely negative parasitological findings were obtained, the parasitological examinations were intermittently positive. Reinfection of three of these animals did not result in new positive examinations. However, given the receptiveness of these animals to initial infection with S. venezuelensis and their similarities to human beings, it is proposed that C. penicillata could be used as a nonhuman primate model for experimental strongyloidiasis.

The short-term effects of pentoxifylline (PTX) on granulomatous lesions during Schistosoma mansoni infection in Swiss mice were evaluated. Drug administration was initiated 42 and 140 days post-infection (DPI) for the acute and chronic infection groups, respectively. Treatment was carried out daily with 200 mg/kg (subcutaneous route) of the drug for five consecutive days. Recovery of parasites and tissues was performed at 49 DPI and 147 DPI, respectively. Liver histological analysis showed a decrease in the inflammatory reaction and fibrous content of the granulomas studied, and a significant reduction (P < 0.001) in their mean diameter was observed in the groups of rodents treated with PTX in acute and chronic infection, when compared to their respective control groups. However, no alteration in the number of S. mansoni recovered from the portal system was observed, and egg-laying kinetics was not notably modified by PTX treatment, and the immature stage distribution of S. mansoni eggs showed minor intrinsic variations with no statistical differences in the parameter second-stage/female/g among untreated mice and treated mice in acute and chronic infections, respectively, when evaluated by intestinal oograms. Data obtained indicate probable immunomodulatory effects of PTX in murine schistosomiasis both in acute and chronic infection.

The protection against Schistosoma mansoni infection was evaluated in SWISS mice orally vaccinated with an attenuated strain of Salmonella carrying a Sm14-based DNA vaccine. Although this formulation was not able to afford a reduction in the worm burden, a non-antigen-specific decrease in schistosome-induced granulomatous reaction was verified in livers of mice that received Salmonella.

Background: Schistosomiasis continues to be a significant public health problem. This disease affects 200 million people worldwide and almost 800 million people are at risk of acquiring the infection. Although vaccine development against this disease has experienced more failures than successes, encouraging results have recently been obtained using membrane-spanning protein antigens from the tegument of Schistosoma mansoni. Our group recently identified Sm29, another antigen that is present at the adult worm tegument surface. In this study, we investigated murine cellular immune responses to recombinant (r) Sm29 and tested this protein as a vaccine candidate., Methods and Findings: We first show that Sm29 is located on the surface of adult worms and lung-stage schistosomula through confocal microscopy. Next, immunization of mice with rSm29 engendered 51%, 60% and 50% reduction in adult worm burdens, in intestinal eggs and in liver granuloma counts, respectively (p<0.05). Protective immunity in mice was associated with high titers of specific anti-Sm29 IgG1 and IgG2a and elevated production of IFN-gamma, TNF-alpha and IL-12, a typical Th1 response. Gene expression analysis of worms recovered from rSm29 vaccinated mice relative to worms from control mice revealed a significant (q<0.01) down-regulation of 495 genes and up-regulation of only 22 genes. Among down-regulated genes, many of them encode surface antigens and proteins associated with immune signals, suggesting that under immune attack schistosomes reduce the expression of critical surface proteins., Conclusion: This study demonstrates that Sm29 surface protein is a new vaccine candidate against schistosomiasis and suggests that Sm29 vaccination associated with other protective critical surface antigens is the next logical strategy for improving protection.

We report the oral vaccination of SWISS mice with an Aro attenuated Salmonella enterica var. Typhimurium vaccine strain expressing the 14-kDa Schistosoma mansoni antigen, Sm14. Bacterial adjuvants, including (i) Lactococcus lactis expressing interleukin-12 (IL-12) and (ii) Lactobacillus delbrueckii UFV-H2b20, were also employed in oral immunization assays. Detection assays to specific IgG and IgA anti-Sm14 antibodies were performed to evaluate humoral immune responses in vaccinated mice. An increase in specific IgG titers was observed; however, no IgA production was detected. The protection levels against schistosomiasis (34.9-49.5%) obtained with all experimental formulations in this work were very similar to values reported by previous studies, which used purified recombinant Sm14 for parenteral vaccination of mice. There was a slight reduction in hepatic granulomas of mice vaccinated with Salmonella. Oogram studies showed diminished numbers of S. mansoni eggs in the intestinal wall of vaccinated mice, but individual female worm fecundity did not seem to be affected by our immunization protocol.