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BACKGROUND: The impact of Schistosoma mansoni infection over the immune response and the mechanisms involved in pathogenesis are not yet completely understood. OBJECTIVES: This study aimed to evaluate the expression of innate immune receptors in three distinct mouse lineages (BALB/c, C57BL/6 and Swiss) during experimental S. mansoni infection with LE strain. METHODS: The parasite burden, intestinal tissue oogram and presence of hepatic granulomas were evaluated at 7- and 12-weeks post infection (wpi). The mRNA expression for innate Toll-like receptors, Nod-like receptors, their adaptor molecules, and cytokines were determined at 2, 7 and 12 wpi in the hepatic tissue by real-time quantitative polymerase chain reaction (qPCR). FINDINGS: Swiss mice showed 100% of survival, had lower parasite burden and intestinal eggs, while infected BALB/c and C57BL/6 presented 80% and 90% of survival, respectively, higher parasite burden and intestinal eggs. The three mouse lineages displayed distinct patterns in the expression of innate immune receptors, their adaptor molecules and cytokines, at 2 and 7 wpi. MAIN CONCLUSIONS: Our results suggest that the pathogenesis of S. mansoni infection is related to a dynamic early activation of innate immunity receptors and cytokines important for the control of developing worms.

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BACKGROUND The impact of Schistosoma mansoni infection over the immune response and the mechanisms involved in pathogenesis are not yet completely understood. OBJECTIVES This study aimed to evaluate the expression of innate immune receptors in three distinct mouse lineages (BALB/c, C57BL/6 and Swiss) during experimental S. mansoni infection with LE strain. METHODS The parasite burden, intestinal tissue oogram and presence of hepatic granulomas were evaluated at 7- and 12-weeks post infection (wpi). The mRNA expression for innate Toll-like receptors, Nod-like receptors, their adaptor molecules, and cytokines were determined at 2, 7 and 12 wpi in the hepatic tissue by real-time quantitative polymerase chain reaction (qPCR). FINDINGS Swiss mice showed 100% of survival, had lower parasite burden and intestinal eggs, while infected BALB/c and C57BL/6 presented 80% and 90% of survival, respectively, higher parasite burden and intestinal eggs. The three mouse lineages displayed distinct patterns in the expression of innate immune receptors, their adaptor molecules and cytokines, at 2 and 7 wpi. MAIN CONCLUSIONS Our results suggest that the pathogenesis of S. mansoni infection is related to a dynamic early activation of innate immunity receptors and cytokines important for the control of developing worms.

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Species of the family Reniferidae are trematodes found in the oral cavity and esophagus of snakes from Nearctic and Neotropical regions. Although Renifer heterocoelium has been reported in different snake species from South America, the snails involved in its transmission remain unknown. In this study, a xiphidiocercaria emerged from the physid snail Stenophysa marmorata from Brazil and was subjected to morphological and molecular study. The general morphology, including the shape of the stylet and arrangement of penetration glands, resembles that described for reniferid trematodes from North America. Phylogenetic analysis on the basis of nuclear sequences (28S ribosomal deoxyribonucleic acid gene [1,072 base pairs {bp}] and internal transcribed spacer region [ITS, 1,036 bp]) supports identifying this larva as a member of the family Reniferidae, very possibly a species of the genus Renifer. In the 28S analysis, low molecular divergences were found to Renifer aniarum (1.4%) and Renifer kansensis (0.6%), but also concerning other 2 reniferid species, i.e., Dasymetra nicolli (1.4%) and Lechriorchis tygarti (1.0%). Regarding ITS, the divergences between this Brazilian cercaria and R. aniarum or L. tygarti were 1.9% and 8.5%, respectively. In the case of the mitochondrial marker cytochrome oxidase subunit 1 (797 bp), our Reniferidae gen. sp. differs 8.6-9.6% from Paralechriorchis syntomentera, the only reniferid with sequences available for comparison. We discuss the probable conspecificity of the larval stages here reported with R. heterocoelium, the reniferid species reported in South America.

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Echinostomatid digeneans belonging to the genus Rhopalias are intestinal trematodes found mainly in opossums in the New World. The genus comprises seven species, but their life cycles and intermediate hosts have been unknown until now. During our long-term study carried out in freshwater habitats within the state of Minas Gerais, Southeast Brazil, echinostomatid cercariae lacking collar spines were found in planorbid snails Biomphalaria glabrata, Biomphalaria straminea, Drepanotrema lucidum and Gundlachia ticaga in six different batches of snail samples collected between 2010 and 2019. Morphologically, the larvae reported herein are morphologically consistent with each other and characterized by the presence of 2-3 large ovoid or spherical corpuscles in each main duct of the excretory system, resembling to Cercaria macrogranulosa previously described from the same region of Brazil. Partial sequences of the ITS (ITS1-5.8S-ITS2) region and 28S gene of the nuclear ribosomal RNA operon, and partial sequences of mitochondrial nad1 and cox1 genes were obtained and compared with the data available for members of the family Echinostomatidae. Nuclear markers indicate that all samples of cercariae evaluated in the present study can be assigned to Rhopalias, but distinct from North American isolates of Rhopalias macracanthus, Rhopalias coronatus and Rhopalias oochi (divergence 0.2-1.2% in 28S and 0.8-4.7% in ITS). The lack of differences verified in both 28S and ITS in 5 out 6 studied samples suggested that they belong to the same species. However, nad1 sequences revealed that our cercariae correspond to three distinct species of Rhopalias (interspecific divergence: 7.7-9.9%), named here as Rhopalias sp. 1, found in B. straminea and G. ticaga, Rhopalias sp. 2 found in B. glabrata and D. lucidum, and Rhopalias sp. 3 also found in D. lucidum. They also differ by 10.8-17.2% from a North American isolate of R. macracanthus sequenced in this study. The cox1 sequences obtained for Rhopalias sp. 1 and Rhopalias sp. 2 (but not Rhopalias sp. 3) reveal that they are distinct from North American isolates of R. macracanthus (genetic divergence 16.3-16.5% and 15.6-15.7%, respectively), R. coronatus (9.2-9.3% and 9.3-9.5%) and Rhopalias oochi (9.0% and 9.5-10.1%). Encysted metacercariae with general morphology similar to that of the body of cercariae were found in tadpoles of Rhinella sp. from the same stream where snails harbored Rhopalias sp. 2, suggesting that the amphibians could act as second intermediate hosts of species of Rhopalias. Data obtained provide the first insights into the life cycle of this unusual echinostomatid genus.

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A list of Gerromorpha species collected from 2016 to 2023 in the State of Rio Grande do Norte, northeastern Brazil, is presented. Previously, only five species had been recorded from this state. In the present study, based on the compilation of data and new collections, 27 species are recorded from the state, of which 23 represent new records. These species belong to 17 genera and five families: Brachymetra Mayr, 1865; Cylindrostethus Fieber, 1861; Halobates Eschscholtz, 1822; Halobatopsis Bianchi, 1896; Husseyella Herring, 1955; Limnogonus Stl, 1868; Microvelia Westwood, 1834; Neogerris Matsumura, 1913; Ovatametra Kenaga, 1942; Rheumatobates Bergroth, 1892 (Gerridae); Lipogomphus Berg, 1879 (Hebridae); Hydrometra Latreille, 1797 (Hydrometridae); Mesovelia Mulsant & Rey, 1852 (Mesoveliidae); Paravelia Breddin, 1898; Platyvelia Polhemus & Polhemus, 1993; Rhagovelia Mayr, 1865; Stridulivelia Hungerford, 1929 (Veliidae). All collected species are illustrated, and their distributions in the state of Rio Grande do Norte are represented in maps. Also, Neogerris celeris (Drake & Harris, 1934) is proposed here as a junior synonym of N. lotus (White, 1879); the lectotype of the latter is designated.

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Philophthalmosis is a zoonotic ocular disease that affects mainly domestic and wild avian species in different parts of the world. However, aspects related to its epizoology in domestic animals are not completely known. In the present study, 47 Muscovy duck (Cairina moschata), 8 mallards (Anas platyrhynchos platyrhynchos) and 6 African geese (Anser cygnoides), free-living in an urban lake in Belo Horizonte, Minas Gerais, Brazil, were evaluated for eye fluke infection. The animals were manually contained, and the conjunctival sac and nictitating membrane were evaluated by direct ophthalmic examination (DOE), in which the fluke burden was estimated by a semiquantitative scale. Moreover, the conjunctival sac lavage (CSL) technique was applied for the search of parasite eggs. When possible, the detected trematodes were carefully removed for fixed for taxonomic identification. In order to characterize the parasite-host-environmental system, malacological collections were performed at the locality, and the collected intermediate host mollusks (Melanoides tuberculata) were evaluated for infection with larval philophthalmids. In addition, wild vertebrates found dead in the locality, including one common gallinule (Gallinula galeata) and two capybaras (Hydrochoerus hydrochaeris), were necropsied for the search of eye flukes. Samples from the developmental stages obtained from the hosts were subjected to morphological and molecular studies (amplification and sequencing of a partial region of the Nad-1 gene). In the DOE, the presence of eye flukes was verified in 67% (4/6), 31% (15/47) and 25% (2/8) in geese, Muscovy ducks and mallards, respectively. In most cases, the birds showed mild parasitism (1-5 trematodes), with no apparent eye damage, characterizing a subclinical infection. In only one goose, which had a high fluke burden (20 trematodes), it was possible to obtain eggs by CSL. Regarding the malacological survey, 73/4545 (1.6%) specimens of M. tuberculata evaluated were found infected with megalurous cercariae, compatible with representatives of the family Philophthalmidae. Additionally, 147 flukes were recovered from a specimen of G. galeata found dead at the lake. The morphological and molecular study of parasites obtained from different hosts evaluated in this study enabled the identification of Philophthalmus gralli, a species native from Asia and introduced in the Americas. Factors such as the wide distribution of the intermediate host and the participation of domestic and wild reservoirs in the parasite transmission chain may favor the occurrence of parasite spillover from wild to domestic birds. Furthermore, the occurrence of the life cycle of P. gralli in an urban waterbody serves as an alert to the possibility of human cases of this zoonotic eye parasite.

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When subjected to molecular study, species of digeneans believed to be cosmopolitan are usually found to consist of complexes of species with narrower distributions. We present molecular and morphological evidence of transcontinental distributions in two species of Apharyngostrigea Ciurea, 1924, based on samples from Africa and the Americas. Sequences of cytochrome c oxidase I and, in some samples, internal transcribed spacer, revealed Apharyngostrigea pipientis (Faust, 1918) in Tanzania (first known African record), Argentina, Brazil, USA and Canada. Sequences from A. pipientis also match previously published sequences identified as Apharyngostrigea cornu (Zeder, 1800) originating in Mexico. Hosts of A. pipientis surveyed include definitive hosts from the Afrotropic, Neotropic and Nearctic, as well as first and second intermediate hosts from the Americas, including the type host and type region. In addition, metacercariae of A. pipientis were obtained from experimentally infected Poecilia reticulata, the first known record of this parasite in a non-amphibian second intermediate host. Variation in cytochrome c oxidase I haplotypes in A. pipientis is consistent with a long established, wide-ranging species with moderate genetic structure among Nearctic, Neotropic and Afrotropic regions. We attribute this to natural dispersal by birds and find no evidence of anthropogenic introductions of exotic host species. Sequences of CO1 and ITS from adult Apharyngostrigea simplex (Johnston, 1904) from Egretta thula in Argentina matched published data from cercariae from Biomphalaria straminea from Brazil and metacercariae from Cnesterodon decemmaculatus in Argentina, consistent with previous morphological and life-cycle studies reporting this parasite-originally described in Australia-in South America. Analyses of the mitochondrial genome and rDNA operon from A. pipientis support prior phylogenies based on shorter markers showing the Strigeidae Railliet, 1919 to be polyphyletic.

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Xiphidiocercariae were found in the invasive snail Melanoides tuberculata collected during a malacological survey in Ceará-Mirim, State of Rio Grande do Norte, Northeastern Brazil in November 2018 and submitted to morphological and molecular analyses. The morphology revealed similarities between the larvae here reported for the first time in M. tuberculata from Brazil and other xiphidiocercariae described in thiarid snails from Asia and Africa. Phylogenetic analyses based on 28S and ITS-2 sequences revealed that the larvae correspond to an unidentified species of the family Lecithodendriidae. Aspects related to the morphology and taxonomy of xiphidiocercariae found in M. tuberculata are briefly discussed. It is possible that the parasite here reported is a newly introduced species transmitted by M. tuberculata in the American continent.

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BACKGROUND: The successive reports of Platynosomum illiciens in Neotropical captive primates have increased interest in platynosomosis; however, its treatment is little known. METHODS: Callithrix penicillata (n = 10) naturally and chronically infected with P. illiciens were treated with praziquantel (25 mg/kg BW, three s.c. doses at 24 hours intervals), and coproparasitological tests performed over 67 days. The proportions of primates with a reduction in fecal egg counts (FEC) or negative results progressively increased after treatment, and at the last fecal tests, marmosets were negative. RESULTS AND CONCLUSIONS: Although all primates tolerated the initial days of study well, 40% (4/10) of them died between the 8th and 16th days after the onset of treatment. Clinical signs and necropsies indicated the occurrence of hepatic involvement, biliary obstruction, and cholangitis. Marmosets with a higher previous FEC were more likely to die after treatment. Use of praziquantel should be considered carefully on a case-by-case basis.

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Trematodes belonging to the superfamily Diplostomoidea have complex life cycles involving birds, mammals and reptiles as definitive hosts, and gastropods and different groups of invertebrates and vertebrates as intermediate hosts. Molecular studies of these parasites are numerous, but data from larval stages in molluscs remain scarce, particularly in South America. The present study focused mainly on five morphotypes of longifurcate cercariae found in Biomphalaria straminea (Dunker, 1848) from Belo Horizonte, Minas Gerais, Brazil, collected between 2009 and 2017. In each morphotype, nuclear internal transcribed spacer (ITS1-5.8S ITS-2) rDNA and mitochondrial cytochrome c oxidase 1 (COI) genes were sequenced. Laboratory-reared fish, Poecilia reticulata Peters, 1859 or snails, Biomphalaria glabrata (Say, 1818) were exposed to cercariae to obtain metacercariae. The morphology of cercariae, experimentally obtained metacercariae, and phylogenetic analyses led to the identification of three species of Diplostomidae [Austrodiplostomum compactum (Lutz, 1928), Crassiphialinae gen. sp. and Hysteromorpha sp.] and two species of Strigeidae (Cotylurus sp., Apharyngostrigea sp.). Previously published sequences allowed species-level identification for only A. compactum, although provisional identifications were possible in two cases. First, the COI from cercariae of Apharyngostrigea sp. in Brazil matched those of metacercariae from naturally infected Cnesterodon decemmaculatus (Jenyns, 1842) in Argentina; although a positive identification is not possible, the material presents morphological similarities with larval stages previously described for A. simplex. Secondly, Cotylurus sp. resembles C. lutzi. Our analysis of previously published COI sequences suggests that Cotylurus cornutus (Rudolphi, 1808) has a Holarctic distribution. Both the morphology of experimentally obtained metacercariae and COI sequences indicate that Hysteromorpha sp. in Brazil is distinct from congeners in North America [Hysteromorpha corti (Hughes, 1929)] and Europe [Hysteromorpha triloba (Rudolphi, 1819)].

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Species of the genus Posthodiplostomum are intestinal parasites of piscivorous birds with worldwide distribution. Recent molecular surveys have focused on developmental stages from vertebrate hosts, with few sequences from larvae found in molluscs. Moreover, most published molecular data are from collections in North America, Europe and Asia, and there are no data for South American species. In the present study, cercariae found in the freshwater limpet Gundlachia ticaga from Brazil were used for morphological, experimental and molecular studies. The longifurcate cercariae, Neascus-type metacercariae obtained in experimentally infected guppies (Poecilia reticulata), and an adult parasite recovered from a mouse were morphologically identified as Posthodiplostomum nanum. Sequences of DNA from internal transcribed spacer (ITS) rDNA and cytochrome c oxidase 1 (cox1) from the cercariae and metacercariae were compared with published data, yielding no matches (ITS divergence ≥ 5.5%, cox1 ≥ 13.9%). Phylogenetic analyses of the ITS sequences suggest paraphyly within the genus Posthodiplostomum, or misidentifications of parasites in molecular studies. For example, ITS sequences of Mesoophorodiplostomum pricei and Posthodiplostomum centrarchi or the unnamed species Posthodiplostomum sp. 8 diverge by only 1.1-1.2% and 0.6%, respectively, and all three species fall within a well-supported clade, suggesting that these isolates are congeneric. The phylogenetic tree obtained for cox1 sequences, although not well resolved, reveals that the type species of the genus, Posthodiplostomum cuticola, does not group with any species previously identified as Posthodiplostomum. Overall, the analyses of molecular data here obtained for P. nanum compared with sequences of related species suggest that a review of this group is necessary. Such studies may result in a split of the genus Posthodiplostomum and the transference of some species currently assigned in this genus to other already described genera.

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Abstract Accurate distributional information is crucial for studies on systematics, biodiversity and conservation. To improve the knowledge regarding the geographical distribution of Omalonyx in South America, we present updated information based on data from a literature review, institutional collections and malacological surveys. All this information composed the dataset used to predict species distribution employing the Maximum Entropy Algorithm (MaxEnt). The model was run using data on species distribution, altitude and bioclimatic variables (WorldClim database). The model had consistent performance, and areas presenting similar conditions to areas where the species were recorded were considered areas of occurrence. The predicted occurrence areas included those that were already surveyed and those that are considered potential occurrence areas. The results demonstrate that the genus has widespread distribution in the Neotropical region and occurs in the tropical, temperate and arid regions of South America and Lesser Antilles. Omalonyx spp. were recorded in all South American countries and hydrographic regions. However, in some countries, there were only isolated records (ex: Colombia and Ecuador). Here, we also present the first record of Omalonyx spp. in four Brazilian States (Acre, Rondônia, Piaui, and Amapá). The genus was found in all hydrographic regions within Brazil and among 27 federative unities; it was absent from only two unities (Roraima State and Distrito Federal). This work contributes to the knowledge on Omalonyx spp. distribution and provides an important basis for the work of ecologists and taxonomists.

Resumo A informação precisa sobre a distribuição é crucial para os estudos sobre sistemática, biodiversidade e conservação. Para melhorar o conhecimento sobre a distribuição geográfica de Omalonyx na América do Sul, apresentamos informações atualizadas com base em dados de revisão de literatura, coleções institucionais e pesquisas malacológicas. Toda essa informação compôs o conjunto de dados usado para predição da distribuição de espécies empregando o Algoritmo de Entropia Máxima (MaxEnt). O modelo foi executado usando dados de distribuição de espécies, altitude e variáveis bioclimáticas (banco de dados WorldClim). O modelo apresentou um desempenho consistente e as áreas que apresentaram condições semelhantes às áreas onde as espécies foram registradas, foram consideradas áreas de ocorrência. As áreas de ocorrências previstas incluíram aquelas que já foram pesquisadas e aquelas que são consideradas áreas de ocorrência potencial. Os resultados demonstram que o gênero tem uma distribuição Neotropical ampla e que ocorre nas regiões tropical, temperada e árida da América do Sul e nas Pequenas Antilhas. Omalonyx spp. foram registradas em todos os países e bacias sul-americanas. No entanto, em alguns países, apenas registros isolados foram encontrados (ex: Colômbia e Equador). Aqui, também apresentamos o primeiro registro de Omalonyx spp. em quatro estados brasileiros (Acre, Rondônia, Piauí e Amapá). O gênero foi encontrado em todas as regiões hidrográficas no Brasil e nas 27 unidades federativas; sendo ausente em apenas duas unidades federativas (Estado de Roraima e Distrito Federal). Esse trabalho contribui para o conhecimento da distribuição das espécies de Omalonyx e fornece uma importante base para trabalhos de ecólogos e taxonomistas.

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Repetitive DNAs are abundant fast-evolving components of eukaryotic genomes, which often possess important structural and functional roles. Despite their ubiquity, repetitive DNAs are poorly studied when compared with the genic fraction of genomes. Here, we took advantage of the availability of the sequenced genome of the common marmoset Callithrix jacchus to assess its satellite DNAs (satDNAs) and their distribution in Callitrichini. After clustering analysis of all reads and comparisons by similarity, we identified a satDNA composed by 171 bp motifs, named MarmoSAT, which composes 1.09% of the C. jacchus genome. Fluorescent in situ hybridization on chromosomes of species from the genera Callithrix, Mico and Callimico showed that MarmoSAT had a subtelomeric location. In addition to the common monomeric, we found that MarmoSAT was also organized in higher-order repeats of 338 bp in Callimico goeldii. Our phylogenetic analyses showed that MarmoSAT repeats from C. jacchus lack chromosome-specific features, suggesting exchange events among subterminal regions of non-homologous chromosomes. MarmoSAT is transcribed in several tissues of C. jacchus, with the highest transcription levels in spleen, thymus and heart. The transcription profile and subtelomeric location suggest that MarmoSAT may be involved in the regulation of telomerase and modulation of telomeric chromatin.

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Species of the genus Spirometra are diphyllobothriid tapeworms with complex life cycles and are involved in human sparganosis, a neglected disease that affects individuals worldwide. Although some species were reported in wild felids and human cases of sparganosis were described in Brazil, the biology and taxonomy of these parasites are poorly understood. In the present study, samples of diphyllobothriids (eggs and/or proglottids) obtained from the stools of wild carnivores (Leopardus pardalis and Lycalopex vetulus) and plerocercoid larvae found in a snake (Crotalus durissus) from Brazil were analysed by amplifying a fragment of the gene cytochrome c oxidase subunit 1 (cox 1). The DNA sequences obtained here for the first time from the Spirometra spp. from Brazil were used to evaluate the phylogenetic relationships with other species. Molecular data identified two species in the Brazilian samples (evolutionary divergence of 17.8-19.2%). The species were identified as Spirometra sp. 1, found in Le. pardalis, and Spirometra sp. 2 found in Ly. vetulus and C. durissus, and they differed from Asian isolates of Spirometra erinaceieuropaei (17.5-20.2% and 12.2-15.6%, respectively), a species previously considered to be distributed worldwide. Moreover, Spirometra sp. 1 is genetically distinct from Sparganum proliferum from Venezuela (19.6-20.4%), while Spirometra sp. 2 is more closely related with the Venezuelan species (6.1-7.0%). Sequences of Spirometra sp. 2 revealed that it is conspecific with the Argentinean isolate of Spirometra found in Lycalopex gymnocercus (1.9-2.2%). Taxonomic and phylogenetic aspects related to New World species of Spirometra are briefly discussed.

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Eurytremiasis is an important parasitic disease of cattle that was recently suggested to be a neglected and emerging human disease in Brazil. Based on a misinterpretation of the life cycle of the parasite, it was suggested that a great number of people could be infected with this fluke in the country. In the present letter, aspects of the life cycle of Eurytrema spp. are revisited and clarified. The mechanism of transmission previously reported for the few accidental human cases involved the ingestion of raw or undercooked insects (grasshoppers and crickets) harboring the infective metacercariae. In reality, the zoonotic potential of Eurytrema species is extremely low, and human eurytremiasis is not, and probably never will be, a zoonotic disease in countries where entomophagy is not a common food habit.

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Trematodes belonging to the family Spirorchiidae are blood parasites mainly of turtles with a worldwide distribution. These flukes were recently reported in some marine turtles from South America, where the occurrence of spirorchiids in freshwater definitive and intermediate hosts is so far unknown. In the present study, three morphotypes of brevifurcate apharyngeate distome cercariae found in freshwater molluscs from an urban reservoir in Brazil were used for morphological and molecular (nuclear 28S rDNA) evaluation. Two morphotypes of cercariae, probably congeneric species, were found in 12/17,465 specimens of Biomphalaria spp. and differ from each other by body size and sequences (0.1%). They present morphology similar to North American freshwater spirorchiids (Spirorchis spp.), however surprisingly molecular data reveals that these lineages are more closely related to marine spirorchiids. A third species found in 2/777 Pomacea sp. differs morphologically from all previously described spirorchiid cercariae and genetically from spirorchiids with available sequences (16-19%), grouping in the phylogenetic tree with freshwater North American species. This is the first report of freshwater spirorchiids in South America and the first molecular confirmation of the involvement of a caenogastropod in the life cycle of spirorchiids.

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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.

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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.

A platinossomose é uma infecção parasitária relatada em primatas não-humanos, inclusive saguis, cujo diagnóstico é frequentemente difícil. Neste estudo, os métodos de sedimentação espontânea e Kato-Katz foram avaliados quanto à sua utilidade na identificação de ovos de Platynosomum em amostras fecais de Callithrix penicillata naturalmente albergando Platynosomum illiciens. A sedimentação espontânea permitiu o diagnóstico de 41,7% (5/12) e 66,7% (8/12) dos saguis infectados a partir da análise de uma e três lâminas, respectivamente, preparadas de uma mesma amostra fecal. O exame de uma única lâmina de Kato-Katz detectou 83,3% (10/12) dos casos de infecção. A análise de fezes em três dias diferentes aumentou as taxas de diagnóstico, uma vez que 75% (9/12) e 100% (12/12) dos primatas que apresentaram a platinossomose foram identificados, usando-se a sedimentação espontânea (três lâminas/dia) e o Kato-Katz em série, respectivamente. O número médio de ovos de Platynosomum por g de fezes, determinado através do método de Kato-Katz, foi de 71,7 (8-240). O método de sedimentação espontânea, quando realizado em série, é aceitável para o diagnóstico da platinossomose. Entretanto, o método de Kato-Katz, o qual foi pela primeira vez usado para se detectar essa infecção, mostrou uma maior sensibilidade diagnóstica, com a vantagem de que é possível uma análise quantitativa dos ovos liberados nas fezes do hospedeiro.

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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.(AU)

A platinossomose é uma infecção parasitária relatada em primatas não-humanos, inclusive saguis, cujo diagnóstico é frequentemente difícil. Neste estudo, os métodos de sedimentação espontânea e Kato-Katz foram avaliados quanto à sua utilidade na identificação de ovos de Platynosomum em amostras fecais de Callithrix penicillata naturalmente albergando Platynosomum illiciens. A sedimentação espontânea permitiu o diagnóstico de 41,7% (5/12) e 66,7% (8/12) dos saguis infectados a partir da análise de uma e três lâminas, respectivamente, preparadas de uma mesma amostra fecal. O exame de uma única lâmina de Kato-Katz detectou 83,3% (10/12) dos casos de infecção. A análise de fezes em três dias diferentes aumentou as taxas de diagnóstico, uma vez que 75% (9/12) e 100% (12/12) dos primatas que apresentaram a platinossomose foram identificados, usando-se a sedimentação espontânea (três lâminas/dia) e o Kato-Katz em série, respectivamente. O número médio de ovos de Platynosomum por g de fezes, determinado através do método de Kato-Katz, foi de 71,7 (8-240). O método de sedimentação espontânea, quando realizado em série, é aceitável para o diagnóstico da platinossomose. Entretanto, o método de Kato-Katz, o qual foi pela primeira vez usado para se detectar essa infecção, mostrou uma maior sensibilidade diagnóstica, com a vantagem de que é possível uma análise quantitativa dos ovos liberados nas fezes do hospedeiro.(AU)

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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.

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