Population genomics of post-glacial western Eurasia.

Western Eurasia witnessed several large-scale human migrations during the Holocene1-5. Here, to investigate the cross-continental effects of these migrations, we shotgun-sequenced 317 genomes-mainly from the Mesolithic and Neolithic periods-from across northern and western Eurasia. These were imputed alongside published data to obtain diploid genotypes from more than 1,600 ancient humans. Our analyses revealed a 'great divide' genomic boundary extending from the Black Sea to the Baltic. Mesolithic hunter-gatherers were highly genetically differentiated east and west of this zone, and the effect of the neolithization was equally disparate. Large-scale ancestry shifts occurred in the west as farming was introduced, including near-total replacement of hunter-gatherers in many areas, whereas no substantial ancestry shifts happened east of the zone during the same period. Similarly, relatedness decreased in the west from the Neolithic transition onwards, whereas, east of the Urals, relatedness remained high until around 4,000 BP, consistent with the persistence of localized groups of hunter-gatherers. The boundary dissolved when Yamnaya-related ancestry spread across western Eurasia around 5,000 BP, resulting in a second major turnover that reached most parts of Europe within a 1,000-year span. The genetic origin and fate of the Yamnaya have remained elusive, but we show that hunter-gatherers from the Middle Don region contributed ancestry to them. Yamnaya groups later admixed with individuals associated with the Globular Amphora culture before expanding into Europe. Similar turnovers occurred in western Siberia, where we report new genomic data from a 'Neolithic steppe' cline spanning the Siberian forest steppe to Lake Baikal. These prehistoric migrations had profound and lasting effects on the genetic diversity of Eurasian populations.

An integrative skeletal and paleogenomic analysis of stature variation suggests relatively reduced health for early European farmers.

Human culture, biology, and health were shaped dramatically by the onset of agriculture ∼12,000 y B.P. This shift is hypothesized to have resulted in increased individual fitness and population growth as evidenced by archaeological and population genomic data alongside a decline in physiological health as inferred from skeletal remains. Here, we consider osteological and ancient DNA data from the same prehistoric individuals to study human stature variation as a proxy for health across a transition to agriculture. Specifically, we compared "predicted" genetic contributions to height from paleogenomic data and "achieved" adult osteological height estimated from long bone measurements for 167 individuals across Europe spanning the Upper Paleolithic to Iron Age (∼38,000 to 2,400 B.P.). We found that individuals from the Neolithic were shorter than expected (given their individual polygenic height scores) by an average of −3.82 cm relative to individuals from the Upper Paleolithic and Mesolithic (P = 0.040) and −2.21 cm shorter relative to post-Neolithic individuals (P = 0.068), with osteological vs. expected stature steadily increasing across the Copper (+1.95 cm relative to the Neolithic), Bronze (+2.70 cm), and Iron (+3.27 cm) Ages. These results were attenuated when we additionally accounted for genome-wide genetic ancestry variation: for example, with Neolithic individuals −2.82 cm shorter than expected on average relative to pre-Neolithic individuals (P = 0.120). We also incorporated observations of paleopathological indicators of nonspecific stress that can persist from childhood to adulthood in skeletal remains into our model. Overall, our work highlights the potential of integrating disparate datasets to explore proxies of health in prehistory.

Tracking the recruitment and evolution of snake toxins using the evolutionary context provided by the Bothrops jararaca genome.

Venom is a key adaptive innovation in snakes, and how nonvenom genes were co-opted to become part of the toxin arsenal is a significant evolutionary question. While this process has been investigated through the phylogenetic reconstruction of toxin sequences, evidence provided by the genomic context of toxin genes remains less explored. To investigate the process of toxin recruitment, we sequenced the genome of Bothrops jararaca, a clinically relevant pitviper. In addition to producing a road map with canonical structures of genes encoding 12 toxin families, we inferred most of the ancestral genes for their loci. We found evidence that 1) snake venom metalloproteinases (SVMPs) and phospholipases A2 (PLA2) have expanded in genomic proximity to their nonvenomous ancestors; 2) serine proteinases arose by co-opting a local gene that also gave rise to lizard gilatoxins and then expanded; 3) the bradykinin-potentiating peptides originated from a C-type natriuretic peptide gene backbone; and 4) VEGF-F was co-opted from a PGF-like gene and not from VEGF-A. We evaluated two scenarios for the original recruitment of nontoxin genes for snake venom: 1) in locus ancestral gene duplication and 2) in locus ancestral gene direct co-option. The first explains the origins of two important toxins (SVMP and PLA2), while the second explains the emergence of a greater number of venom components. Overall, our results support the idea of a locally assembled venom arsenal in which the most clinically relevant toxin families expanded through posterior gene duplications, regardless of whether they originated by duplication or gene co-option.

Ultrasonographic and radiographic evaluation of gestation in golden lanceheads (Bothrops insularis) in ex situ breeding programs.

The golden lancehead (Bothrops insularis) is a critically endangered snake endemic to Queimada Grande Island, southeastern Brazil. Captive breeding programs are vital for the conservation of this species. This study evaluates the gestation of two females golden lanceheads using radiography and ultrasonography. The first female was collected on the island while reproductively active (late vitellogenesis or early pregnancy) and kept in captivity. This female gave birth to five neonates after an 8-month gestation period, which is longer than estimates based on specimens preserved in museums. The second female copulated in captivity in July and probably ovulated in October. In this case, no embryonic development was detected, and the female deposited 14 undeveloped eggs approximately 6 months after ovulation.

Skin fibrosis associated with keloid, scleroderma and Jorge Lobo's disease (lacaziosis): An immuno-histochemical study.

Fibrosis is a common pathophysiological response of many tissues and organs subjected to chronic injury. Despite the diverse aetiology of keloid, lacaziosis and localized scleroderma, the process of fibrosis is present in the pathogenesis of all of these three entities beyond other individual clinical and histological distinct characteristics. Fibrosis was studied in 20 samples each of these three chronic cutaneous inflammatory diseases. An immunohistochemical study was carried out to explore the presence of α-smooth muscle actin (α-SMA) and vimentin cytoskeleton antigens, CD31, CD34, Ki67, p16; CD105, CD163, CD206 and FOXP3 antigens; and the central fibrotic cytokine TGF-ß. Higher expression of vimentin in comparison to α-SMA in all three lesion types was found. CD31- and CD34-positive blood vessel endothelial cells were observed throughout the reticular dermis. Ki67 expression was low and almost absent in scleroderma. p16-positive levels were higher than ki67 and observed in reticular dermis of keloidal collagen in keloids, in collagen bundles in scleroderma and in the external layers of the granulomas in lacaziosis. The presence of α-actin positive cells and rarely CD34 positive cells, observed primarily in keloids, may be related to higher p16 antigen expression, a measure of cell senescence. Low FOXP3 expression was observed in all lesion types. CD105-positive cells were mainly found in perivascular tissue in close contact with the adventitia in keloids and scleroderma, while, in lacaziosis, these cells were chiefly observed in conjunction with collagen deposition in the external granuloma layer. We did not find high involvement of CD163 or CD206-positive cells in the fibrotic process. TGF-ß was notable only in keloid and lacaziosis lesions. In conclusion, we have suggested vimentin to be the main myofibroblast general marker of the fibrotic process in all three studied diseases, while endothelial-to-mesenchymal transition (EndoMT) and mesenchymal stem cells (MSCs) and M2 macrophages may not play an important role.

Prospecting of essential oils in combination with florfenicol against motile Aeromonas isolated from tambaqui (Colossoma macropomum).

Natural products with antimicrobial activity and their association with synthetic antimicrobials are a sustainable option in fish farming. The objective of this study was to determine antimicrobial activity, antibiofilm potential and synergism of five essential oils (EOs) with florfenicol against motile Aeromonas isolated from Amazonian Colossoma macropomum. As their major constituent, the EOs of the species of Aloysia triphylla, Croton cajucara (red and white morphotype), Cymbopongo citratus and Lippia gracilis present ß-pinene (22.1%), germacrene D (11.5%), linalool (23%), geranial (45.7%) and carvacrol (42.2%), respectively. The EOs of L. gracilis and C. citratus showed the best antimicrobial activities against the Aeromonas strains (5 mg mL-1). All EOs interfered with biofilm formation and consolidated biofilm. The EOs of A. triphylla, C. citratus and L. gracilis showed a synergistic effect with florfenicol, reducing the amount of the chemical into the water systems while treatment.

Mycobacterium leprae diversity and population dynamics in medieval Europe from novel ancient genomes.

BACKGROUND: Hansen's disease (leprosy), widespread in medieval Europe, is today mainly prevalent in tropical and subtropical regions with around 200,000 new cases reported annually. Despite its long history and appearance in historical records, its origins and past dissemination patterns are still widely unknown. Applying ancient DNA approaches to its major causative agent, Mycobacterium leprae, can significantly improve our understanding of the disease's complex history. Previous studies have identified a high genetic continuity of the pathogen over the last 1500 years and the existence of at least four M. leprae lineages in some parts of Europe since the Early Medieval period. RESULTS: Here, we reconstructed 19 ancient M. leprae genomes to further investigate M. leprae's genetic variation in Europe, with a dedicated focus on bacterial genomes from previously unstudied regions (Belarus, Iberia, Russia, Scotland), from multiple sites in a single region (Cambridgeshire, England), and from two Iberian leprosaria. Overall, our data confirm the existence of similar phylogeographic patterns across Europe, including high diversity in leprosaria. Further, we identified a new genotype in Belarus. By doubling the number of complete ancient M. leprae genomes, our results improve our knowledge of the past phylogeography of M. leprae and reveal a particularly high M. leprae diversity in European medieval leprosaria. CONCLUSIONS: Our findings allow us to detect similar patterns of strain diversity across Europe with branch 3 as the most common branch and the leprosaria as centers for high diversity. The higher resolution of our phylogeny tree also refined our understanding of the interspecies transfer between red squirrels and humans pointing to a late antique/early medieval transmission. Furthermore, with our new estimates on the past population diversity of M. leprae, we gained first insights into the disease's global history in relation to major historic events such as the Roman expansion or the beginning of the regular transatlantic long distance trade. In summary, our findings highlight how studying ancient M. leprae genomes worldwide improves our understanding of leprosy's global history and can contribute to current models of M. leprae's worldwide dissemination, including interspecies transmissions.

Assessment of neuromuscular fatigue through frequency analysis of the electromyographic signal of control participants and those with temporomandibular dysfunction treated with resilient or hard occlusal devices.

STATEMENT OF PROBLEM: Muscle hyperactivity that leads to neuromuscular fatigue can be evaluated by electromyography. Whether treatment with occlusal devices can restore neuromuscular balance to patients with temporomandibular disorders (TMDs) is unclear. PURPOSE: The purpose of this clinical study was to evaluate neuromuscular fatigue by analyzing the frequency of the electromyographic signal of the masseter and anterior temporalis muscles on both sides in healthy participants and those with TMD treated with a resilient or hard occlusal device. MATERIAL AND METHODS: One hundred asymptomatic participants and 30 with TMD were divided into 2 groups: treated with a hard device or treated with a resilient device. All underwent electromyographic examination before and after treatment with the occlusal devices. RESULTS: In both groups, the results showed statistically significant differences (P<.01) when the fatigue rate before and after treatment with an occlusal device was compared. CONCLUSIONS: Treatment with both types of occlusal device was efficient in reducing the rate of neuromuscular fatigue in patients with TMDs.

Replacement and Parallel Simplification of Nonhomologous Proteinases Maintain Venom Phenotypes in Rear-Fanged Snakes.

Novel phenotypes are commonly associated with gene duplications and neofunctionalization, less documented are the cases of phenotypic maintenance through the recruitment of novel genes. Proteolysis is the primary toxic character of many snake venoms, and ADAM metalloproteinases, named snake venom metalloproteinases (SVMPs), are largely recognized as the major effectors of this phenotype. However, by investigating original transcriptomes from 58 species of advanced snakes (Caenophidia) across their phylogeny, we discovered that a different enzyme, matrix metalloproteinase (MMP), is actually the dominant venom component in three tribes (Tachymenini, Xenodontini, and Conophiini) of rear-fanged snakes (Dipsadidae). Proteomic and functional analyses of these venoms further indicate that MMPs are likely playing an "SVMP-like" function in the proteolytic phenotype. A detailed look into the venom-specific sequences revealed a new highly expressed MMP subtype, named snake venom MMP (svMMP), which originated independently on at least three occasions from an endogenous MMP-9. We further show that by losing ancillary noncatalytic domains present in its ancestors, svMMPs followed an evolutionary path toward a simplified structure during their expansion in the genomes, thus paralleling what has been proposed for the evolution of their Viperidae counterparts, the SVMPs. Moreover, we inferred an inverse relationship between the expression of svMMPs and SVMPs along the evolutionary history of Xenodontinae, pointing out that one type of enzyme may be substituting for the other, whereas the general (metallo)proteolytic phenotype is maintained. These results provide rare evidence on how relevant phenotypic traits can be optimized via natural selection on nonhomologous genes, yielding alternate biochemical components.

An updated systematic review on the association between Cd exposure, blood pressure and hypertension.

BACKGROUND: Since the first report by Perry et al. (1955), most studies affirmed the hypertensive effects of cadmium (Cd) in humans. Nonetheless, conclusions between studies remain inconsistent. OBJECTIVE: The aim of this study was to reevaluate the evidence for a potential relationship between Cd exposure and altered blood pressure and/or hypertension, focusing on studies published between January 2010 and March 2020. METHODS: We reviewed all observational studies from database searches (PubMed and SCOPUS) on Cd exposure and blood pressure or hypertension. We extracted information from studies that provided sufficient data on population characteristics, smoking status, exposure, outcomes, and design. RESULTS: Thirty-eight studies met our inclusion criteria; of those, twenty-nine were cross sectional, three case control, five cohort and one interventional study. Blood or urinary Cd levels were the most commonly used biomarkers. CONCLUSIONS: A positive association between blood Cd levels and blood pressure and/or hypertension was identified in numerous studies at different settings. Limited number of representative population-based studies of never-smokers was observed, which may have confounded our conclusions. The association between urinary Cd and blood pressure and/or hypertension remains uncertain due to conflicting results, including inverse relationships with lack of strong mechanistic support. We point to the urgent need for additional longitudinal studies to confirm our findings.

Blood cadmium levels and sources of exposure in an adult urban population in southern Brazil.

BACKGROUND: Cadmium (Cd) is a toxic metal that is widely present in the environment due to geologic and anthropogenic sources. Exposures to high Cd levels may cause nephrotoxicity, carcinogenicity, pulmonary and cardiovascular disease, among others. The goal of this study was to investigate in an adult urban population whether an association exists between sources and levels of Cd exposure and blood Cd concentrations. METHODS: Using a census-based design, a total of 959 adults, aged 40 years or older, were randomly selected. Information on socio-demographics, dietary, and lifestyle background was obtained by household interviews. Blood Cd levels were measured by inductively coupled-plasma mass spectrometry. Geometric means (GM) (95% CI) and the 50th percentile were determined, stratified by sex, age, race, education, income class, smoking status, consumption of vegetables, red meat and milk, occupation and blood pressure. To assess the association between Cd exposure and the aforementioned variables, we estimated the geometric mean ratio (GMR) (95%CI) of blood Cd concentrations. RESULTS AND CONCLUSION: The geometric mean (95%CI) of blood Cd levels in the total population was 0.25 (0.22, 0.27) ug/dL. In a univariate analysis, significantly higher blood Cd levels were found in men (p < 0.001), current and former smokers (p < 0.001), alcohol drinkers (p < 0.001), those who never or almost never consumed milk (p < 0.001), and in subjects with higher diastolic blood pressure (p = 0.03). Significant correlations were found between the number of cigarettes consumed daily and blood Cd levels. Multivariate analysis confirmed higher blood Cd concentrations were associated with alcohol consumption (GMR 95%CI = 1.28, 1.04-1.59) and in former and current smokers (GMR 95% IC = 1.33, 1.06-1.67 and 4.23, 3.24-5.52, respectively). Our results shed novel information on variables associated with blood Cd levels in an urban Brazilian population, and should encourage additional research to prevent environmental Cd exposure, both in Brazil and globally.

Cerebrovascular Accidents Related to Snakebites in the Amazon-Two Case Reports.

The objective of this case series was to describe 2 patients presenting with subarachnoid hemorrhage with hydrocephalus and hemoventricle after a snakebite caused by presumed Bothrops ssp. Both cases occurred in the municipality of Guajará (Amazonas state), Western Brazilian Amazon. Both cases featured delay in administration of serum therapy, which may have contributed to the emergence of complications such as stroke. Patient 1 was admitted to hospital 16 h after the snakebite occurred. Before receiving antivenom, testing showed the patient as having unclottable blood. She developed hemorrhagic stroke (a subarachnoid hemorrhage with hydrocephalus and hemoventricle). On the seventh day, she was discharged from hospital. Patient 2 arrived at the hospital 3 d after the snakebite occurred and presented with unclottable blood. He had a stroke (right frontoparietal hemorrhage, intraparenchymal hemorrhage already open to the ventricle) and died on the eighth day after the snakebite. Delay in seeking health care after snake envenomation can result in worse outcome.

Three-Dimensional Nasal Alterations in Le Fort I Advancement: Linear Measurements, Angles, Nasal Indices, and Volume Differences.

The maxillary advancement obtained by the Le Fort I osteotomy can also generate significant changes in the soft tissue of the nose and lips. The aim of this study was to compare the alterations in the soft tissue of the nose following the Le Fort I osteotomy maxillary advancement technique in a population of young adults submitted to orthognathic surgery. Seven men and 8 women aged between 23 and 45 underwent orthognathic surgery using the Le Fort I osteotomy and bilateral mandibular sagittal osteotomy. Sixty 3-dimensional images were analyzed (Vectra M3, Canfield, NJ) after labeling landmarks on the face and determining linear and angular measurements, proportion, and volume difference indices at the following intervals: preoperatively (baseline), then 2 months, 6 months, and 1 year after surgery. Following Le Fort I, there was an increase in the alar base, and reduction of nasal tip protrusion, nasal angles, and the nasal tip protrusion index (P < 0.05). There were no differences in the facial thirds, the nasal index, and angles of nasal and mentolabial convexity (P > 0.05). There was a difference in the volume of the nose only 2 months after surgery. The Le Fort I osteotomy caused significant alterations in linear, angular, and nasal proportion measurements. The volume differences were reversible in the early postoperative period and probably associated with edema. The possibility of variations in the size and shape of the nose should be presented to prospective patients preoperatively.

Did the Romans introduce the Egyptian mongoose (Herpestes ichneumon) into the Iberian Peninsula?

New finds of bones of the Egyptian Mongoose (Herpestes ichneumon), one from Portugal and one from Spain, were directly 14C dated to the first century AD. While the Portuguese specimen was found without connection to the Chalcolithic occupation of the Pedra Furada cave where it was recovered, the Spanish find, collected in the city of Mérida, comes from a ritual pit that also contained three human and 40 dog burials. The finds reported here show that the Egyptian mongoose, contrary to the traditional and predominant view, did not first arrive in the Iberian Peninsula during the Muslim occupation of Iberia. Instead, our findings are consistent with the hypothesis that the species was first introduced by the Romans, or at least sometime during the Roman occupation of Hispania. Therefore, radiocarbon dating of new archaeological finds of bones of the Egyptian Mongoose (Herpestes ichneumon) in the Iberian Peninsula push back the confirmed presence of the species in the region by approximately eight centuries, as the previously oldest dated record is from the ninth century. With these new dates, there are now a total of four 14C dated specimens of Egyptian mongooses from the Iberian Peninsula, and all of these dates fall within the last 2000 years. This offers support for the hypothesis that the presence of the species in Iberia is due to historical introductions and is at odds with a scenario of natural sweepstake dispersal across the Straits of Gibraltar in the Late Pleistocene (126,000-11,700 years ago), recently proposed based on genetic data.

The use of antioxidant agents for chemotherapy-induced peripheral neuropathy treatment in animal models.

Antineoplastic drugs such as cisplatin, oxaliplatin, paclitaxel and vincristin are widely used in the treatment of several solid and blood tumours. However, the severity of peripheral neuropathy caused by these agents can affect the patient's quality of life. The major symptoms of chemotherapy-induced peripheral neuropathy (CIPN) involve: sensory loss, paresthesia, dysesthaesia, numbness, tingling, temperature sensitivity, allodynia and hyperalgesia, in a "stocking and glove" distribution. Why many different chemotherapeutic agents result in similar neuropathy profiles is unclear. Many drug classes such as antidepressants, anticonvulsants, antispastic agents and others have been used in clinical practice, but there is no scientific evidence to prove their effectiveness. But drugs as the antioxidant have shown a protective effect against free radical damage. In order to find out a successful treatment for CIPN, animal studies (ie pharmacological and mechanical tests and histopathological immunohistochemical analyses) have been developed to try to determinate the action of the antioxidant agents. This review provides an overview of the major antioxidant agents recently investigated to treat CIPN and the animal models used for this purpose.

Repeatability Study of Angular and Linear Measurements on Facial Morphology Analysis by Means of Stereophotogrammetry.

The aim of this study was to analyze the repeatability in a stereophotogrammetry digital system used for the evaluation of facial morphology. Thirty healthy Brazilian, 18 to 45 years old (26.71 ±â€Š6.53), had 11 reference landmarks marked on their faces by the same examiner and were photographed with an interval of 1 week by the VECTRA M3. Nine angular measurements (nasolabial, mentolabial, nasofrontal, maxillofacial, nasal, maxillary, mandibular, facial convexity, full facial convexity) and 2 linear measurements (middle facial height and lower facial height) were taken. Repeatability was analyzed by the mean absolute differences, relative error of magnitude, technical error of measurement, intraclass correlation coefficient, and Bland-Altman analysis. Paired t test sought any systematic errors between the acquisitions. Associations among body mass index, age, and the error in the measurements were made using the Pearson correlation coefficient. For the technical error of measurement, the nasolabial and mentolabial angles showed values >2° (clinical limit set for this study). For the relative error of measurement, most of the measures were rated between good and excellent. The maxillofacial angle was only moderate. There was a systematic error for middle facial height. The nasolabial, mentolabial, facial convexity, full facial convexity, maxillofacial, and nasofrontal angles presented intraclass correlation coefficient values rated as excellent. The relationship between age/body mass index and the error found between measurements was not confirmed. The nasolabial and mentolabial angles should be interpreted with caution due to the variability showed. The results found stereophotogrammetry to be repeatable, giving accurate measures within the references established for this study.

Primary dengue haemorrhagic fever in patients from northeast of Brazil is associated with high levels of interferon-ß during acute phase.

Dengue is an acute febrile disease caused by the mosquito-borne dengue virus (DENV) that according to clinical manifestations can be classified as asymptomatic, mild or severe dengue. Severe dengue cases have been associated with an unbalanced immune response characterised by an over secretion of inflammatory cytokines. In the present study we measured type I interferon (IFN-I) transcript and circulating levels in primary and secondary DENV infected patients. We observed that dengue fever (DF) and dengue haemorrhagic fever (DHF) patients express IFN-I differently. While DF and DHF patients express interferon-α similarly (52,71 ± 7,40 and 49,05 ± 7,70, respectively), IFN- ß were associated with primary DHF patients. On the other hand, secondary DHF patients were not able to secrete large amounts of IFN- ß which in turn may have influenced the high-level of viraemia. Our results suggest that, in patients from our cohort, infection by DENV serotype 3 elicits an innate response characterised by higher levels of IFN- ß in the DHF patients with primary infection, which could contribute to control infection evidenced by the low-level of viraemia in these patients. The present findings may contribute to shed light in the role of innate immune response in dengue pathogenesis.

Comparison of dynamic electromyographic analysis of masticatory capsules with materials of different textures.

OBJECTIVES: The aim of this study was to compare the mastication electromyographic indexes of capsules used for the masticatory efficiency evaluation "ME-mastig" and of materials of different textures (gum, raisins, and peanuts). METHODS: Thirty young, healthy, adult subjects, with an average age of 23.46 years old, with no symptoms of temporomandibular dysfunction (TMD), confirmed by the clinical exam, RDC/TMD, and the static test of electromyography (EMG) were chosen. Afterward, dynamic tests were performed (bilateral mastication of the compounds) to determine number of chewing cycles (CYCLES); masticatory frequency (FREQ); SMI (symmetrical masticatory index - corresponding to the value of neuromuscular coordination during mastication); and IMPACT (corresponding to impact - total electromyographic activity performed by the system during chewing). RESULTS: Cycle and frequency were similar. Regarding SMI and IMPACT, the raisin, the capsule, and the peanut were similar between each other, and different from the gum. CONCLUSIONS: Masticatory capsules and the natural foods with different textures had similar results regarding EMG indexes.

The hamster (Mesocricetus auratus) as an experimental model of toxocariasis: histopathological, immunohistochemical, and immunoelectron microscopic findings.

Toxocariasis is a globally distributed parasitic infection caused by the larval stage of Toxocara spp. The typical natural hosts of the parasite are dogs and cats, but humans can be infected by the larval stage of the parasite after ingesting embryonated eggs in soil or from contaminated hands or fomites. The migrating larvae are not adapted to complete their life cycle within accidental or paratenic hosts like humans and laboratory animals, respectively, but they are capable of invading viscera or other tissues where they may survive and induce disease. In order to characterize hamsters (Mesocricetus auratus) as a model for Toxocara canis infection, histopathological and immunohistochemistry procedures were used to detect pathological lesions and the distribution of toxocaral antigens in the liver, lungs, and kidneys of experimentally infected animals. We also attempted to characterize the immunological parameters of the inflammatory response and correlate them with the histopathological findings. In the kidney, a correlation between glomerular changes and antigen deposits was evaluated using immunoelectron microscopy. The hamster is an adequate model of experimental toxocariasis for short-term investigations and has a good immunological and pathological response to the infection. Lung and liver manifestations of toxocariasis in hamsters approximated those in humans and other experimental animal models. A mixed Th2 immunological response to T. canis infection was predominant. The hamster model displayed a progressive rise of anti-toxocaral antibodies with the formation of immune complexes. Circulating antigens, immunoglobulin, and complement deposits were detected in the kidney without the development of a definite immune complex nephropathy.