The enteric protist Blastocystis is one of the most frequently reported parasites infecting both humans and many other animal hosts worldwide. A remarkable genetic diversity has been observed in the species, with 17 different subtypes (STs) on a molecular phylogeny based on small subunit RNA genes (SSU rDNA). Nonetheless, information regarding its distribution, diversity and zoonotic potential remains still scarce, especially in groups other than primates. In Brazil, only a few surveys limited to human isolates have so far been conducted on Blastocystis STs. The aim of this study is to determine the occurrence of Blastocystis subtypes in non-human vertebrate and invertebrate animal groups in different areas of the state of Rio de Janeiro, Brazil. A total of 334 stool samples were collected from animals representing 28 different genera. Blastocystis cultivated samples were subtyped using nuclear small subunit ribosomal DNA (SSU rDNA) sequencing. Phylogenetic analyses and BLAST searches revealed six subtypes: ST5 (28.8%), ST2 (21.1%), ST1 and ST8 (19.2%), ST3 (7.7%) and ST4 (3.8%). Our findings indicate a considerable overlap between STs in humans and other animals. This highlights the importance of investigating a range of hosts for Blastocystis to understand the eco-epidemiological aspects of the parasite and its host specificity.
In low endemicity areas of schistosomiasis, the recommended diagnostic method of coprological examination results in an underestimation of infection cases. Alternative diagnostic methods have been developed, such as immunodiagnostic and molecular techniques. In this study we evaluated three methods used in the diagnosis of Schistosoma mansoni infection: parasitological (Kato-Katz), immunological (ELISA) and molecular (real time PCR), and also investigated the sensitivity of each technique in the cure determination after treatment with praziquantel using the water rat Nectomys squamipes, a natural reservoir for S. mansoni, as an experimental model. Two infection laboratory experiments were carried out. The first experiment aimed to observe the evolution of the immunological response in the first moments after infection and in the first months after treatment. The second experiment aimed to compare the efficacy of the three diagnostic techniques after infection and after treatment over a more extended time period. In the first experiment, 44% of the infected animals showed IgG reactivity after two weeks of infection, and 94% were positive based on serology 30 days after infection. The serological IgG titers increased just after infection but decreased gradually after treatment. In the second experiment, 89% of the animals showed positive IgG titers 22 days after infection. Only 68% of the animals showed positive results on the coproscopic diagnostic analysis and 79% did so by qPCR, 50 days after infection. Treated animals showed negative results on coproscopy one month after treatment but remained positive by serology even 12 months after treatment, although showing a decline in immunologic reaction after treatment. By qPCR analysis, all animals showed negative results three months after treatment, except for one animal. The parasitosis can be detected by coproscopy only six weeks after infection, and by serology 14 days after infection. The qPCR was a better diagnostic method for confirming the infection cure of S. mansoni. In early infection, this method was less efficient than serology but was slightly more efficient than the Kato-Katz method. We suggest that the methods should be used in low endemic areas as follows: serology should be used in the initial diagnosis in a population with potential positive cases; subsequently, coproscopy should be used in IgG positive cases to confirm the current infection; and qPCR should be used to evaluate the infection cure after treatment and is also a very valuable tool when there are cases showing positive IgG and negative coproscopy.
Introduction: Sources of pathogenic Rickettsia in wildlife are largely unknown in Brazil. In this work, potential tick vectors and seroreactivity of small mammals against four spotted-fever group Rickettsia (R. rickettsii, R. parkeri, R. amblyommii and R. rhipicephali) and Rickettsia bellii from peri-urban areas of Uberlândia, a major town in Brazil, are described for the first time. Methodology: Small mammals were captured and blood samples collected. Ticks were collected from the surface of the host and the environment and posteriorly identified. Reactivity of small mammal sera to Rickettsia was tested by indirect immunofluorescence assay (IFA) using crude antigens from five Brazilian Rickettsia isolates. Results: Information was obtained from 416 small mammals (48 Marsupialia and 368 Rodentia). Forty-eight animals were parasitized and two tick species, Ixodes loricatus and Amblyomma dubitatum, were found on several host species, with a few tick-host relationships described for the first time. From the 416 tested sera, 70 reacted to at least one Rickettsia antigen (prevalence of 16.8%) and from these, 19 (27.1%) reacted to two or more antigens. Seroprevalence was higher for marsupials (39.6%) than for rodents (13.8%). Marsupial and Rhipidomys spp. sera reacted mainly (highest seroprevalence and titers) to R. bellii, and that of Necromys lasiurus mainly to R. rickettsii. Conclusions: Although the serologic assays poorly discriminate between closely related spotted-fever group Rickettsia, the observed small mammal seroreactivity suggests the circulation of Rickettsia in the peri-urban area of Uberlândia, albeit at low levels.
Metachirus myosuros is a marsupial species widely distributed in South America. Despite this, there is a lack of knowledge about its helminth parasites and helminth community structure. The aims of this study were to describe the species composition and determine the parasitological parameters of helminth communities of M. myosuros in preserved areas of the Atlantic Forest, Igrapiúna, Bahia state, northeastern Brazil. Parasites were searched from 19 specimens of this marsupial (18 were infected with at least one species), counted and identified. Ten species of helminth parasites were obtained: 7 nematodes, 2 platyhelminths and 1 acanthocephalan. The most abundant species were Aspidodera raillieti, Cruzia tentaculata, Physaloptera mirandai and Viannaia conspicua (Nematoda). These species were also the only dominant ones in the component community. Male hosts had higher prevalence of P. mirandai and greater abundance of V. conspicua. We observed a relationship between host body size and helminth abundance in both male and female hosts, and between host body size and helminth species richness in female hosts. This was the first study to analyze the helminth fauna and helminth community structure of M. myosuros. This was the first report of occurrences of A. raillieti and Didelphonema longispiculata in M. myosuros.
The South American water rat Nectomys squamipes is a wild mammal reservoir of Schistosoma mansoni in Brazil. In the present study, wild rodents were collected in the field and categorized into two groups: infected and uninfected by S. mansoni. Blood was collected to analyze changes in the serum glucose level (mg/dL) and liver fragments were used to determine the hepatic glycogen content (mg of glucose/g tissue). The histological examination showed inflammatory granulomatous lesions in different phases of development in the liver of rodents naturally infected with S. mansoni, in some cases with total or partial occlusion of the vascular lumen. Early lesions were characterized by the presence of inflammatory infiltrate around morphologically intact recently deposited eggs. Despite the significance of these histological lesions, the biochemical changes differed in extent. N. squamipes naturally infected by S. mansoni showed no variation in hepatic glycogen reserves. These findings were accompanied by a significant increase in plasma glucose contents, probably as a consequence of amino acids deamination, which are degraded, resulting in the formation of intermediates used as precursors for the glucose formation, without compromising the reserves of liver glycogen. In the wild, naturally infected N. squamipes can maintain S. mansoni infections without undergoing alterations in its carbohydrate metabolism, which minimizes the deleterious effects of S. mansoni.Keywords: Biochemical alterations, rodents, wild reservoirs, alternative model. ResumoNectomys squamipes é um mamífero silvestre reservatório de Schistosoma mansoni no Brasil. No presente estudo, os roedores silvestres, colhidos no campo, foram classificados em dois grupos: infectado e não infectado por S. mansoni. O sangue foi colhido para análise da alteração no nível de glicose sérico (mg/dL) e fragmentos de fígado foram usados para determinar o conteúdo de glicogênio hepático (mg de glicose/g tecido). A análise histológica demonstrou lesões granulomatosas em diferentes fases de desenvolvimento no tecido hepático dos roedores naturalmente infectados com S. mansoni, localizados principalmente na região periportal, com total ou parcial oclusão do lúmen vascular. As lesões foram caracterizadas por presença de infiltrado inflamatório ao redor de ovos morfologicamente intactos recentemente depositados. Apesar da grande significância das lesões histológicas, as alterações bioquímicas não diferiram no mesmo
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Mammals captured in the Serra dos Órgãos National Park (PARNASO) and the Pedra Branca State Park (PBSP) between 2012 and 2015 were examined for the presence of ticks. In total, 140 mammals were examined, and 34 specimens were found to be parasitized by ticks. Didelphis aurita, Akodon montensis and Oligoryzomys nigripes were the species most parasitized. From these specimens, 146 ticks were collected, including 10 larvae. The ticks belonged to eight species: one in the genus Ixodes and seven in the genus Amblyomma. This study reports new associations of ticks and wild mammals in Brazil.
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