Navegando por Autor "SILVEIRA, Fernando Tobias"

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Acesso aberto (Open Access)
Canine antibody response to Lutzomyia longipalpis saliva in endemic area of visceral leishmaniasis
(Universidade Federal do Pará, 2016-06) BATISTA, Luís Fábio da Silva; MATTA, Vânia Lúcia Ribeiro da; TOMOKANE, Thaise Yumie; PACHECO, Acácio Duarte; SILVEIRA, Fernando Tobias; ROSSI, Claudio Nazaretian; MARCONDES, Mary; LAURENTI, Márcia Dalastra
Introduction: Canine exposure to Lutzomyia longipalpis bites and the potential of Leishmania infantum transmissibility for the vector were evaluated. Methods: Immunoglobulin G (IgG) anti-Lu longipalpis saliva and -L. infantum, and blood parasite load were determined in dogs from endemic areas of visceral leishmaniasis. Results: Blood parasitism was similar between symptomatic and asymptomatic dogs. IgG anti-L. infantum was higher in symptomatic dogs, but IgG anti-Lu. longipalpis saliva was mostly observed in higher titers in asymptomatic dogs, indicating vector preference for feeding on asymptomatic dogs. Conclusions: Our data suggest a pivotal role of asymptomatic dogs in L. infantum transmission in endemic areas.
Acesso aberto (Open Access)
Canine visceral leishmaniasis due to Leishmania (L.) infantum chagasi in Amazonian Brazil: comparison of the parasite density from the skin, lymph node and visceral tissues between symptomatic and asymptomatic, seropositive dogs
(2010-10) LIMA, Luciana Vieira Rego; CARNEIRO, Liliane Almeida; CAMPOS, Marliane Batista; CHAGAS, Eujênia Janis; LAURENTI, Márcia Dalastra; CORBETT, Carlos Eduardo Pereira; LAINSON, Ralph; SILVEIRA, Fernando Tobias
Canine visceral leishmaniasis (CVL) is recognizable by characteristic signs of disease and is highly lethal. The infection, however, may be quite inapparent in some seropositive dogs, and this has raised the polemic question as to whether or not such animals can be a source of infection for Lutzomyia longipalpis, the vector of American visceral leishmaniasis (AVL). In this study we have examined 51 dogs with acute CVL from an AVL area in Pará State, northern Brazil, and compared the parasite density, amastigotes of Leishmania (L.) infantum chagasi, in the skin, lymph node and viscera of symptomatic with that of nine asymptomatic but seropositive dogs (IFAT-IgG). Post-mortem biopsy fragments of these tissues were processed by immunohistochemistry, using a polyclonal antibody against Leishmania sp. The X2 and Mann Whitney tests were used to evaluate the means of infected macrophage density (p < 0.05). There was no difference (p > 0.05) in the skin (10.7/mm2 x 15.5/mm2) and lymph node (6.3/mm2 x 8.3/mm2), between asymptomatic and symptomatic dogs, respectively. It was higher (p < 0.05), however, in the viscera of symptomatic (5.3/mm2) than it was in asymptomatic (1.4/mm2) dogs. These results strongly suggest that asymptomatic or symptomatic L. (L.) i. chagasi-infected dogs can serve as a source of infection, principally considering the highest (p < 0.05) parasite density from skin (10.7/mm2 x 15.5/mm2), the place where the vetor L. longipalpis takes its blood meal, compared with those from lymph node (6.3/mm2 x 8.3/mm2) and viscera (1.4/mm2x 5.3/mm2).
Acesso aberto (Open Access)
Diagnóstico molecular e frequência de anticorpos anti-Leishmania infantum chagasi em cães do município de Belém, Pará
(2014-03) SCHWANKE, Katiane; SILVA, Aryane Maximina Melo da; OLIVEIRA, Adlilton Pacheco de; SILVA, Michele Bahia do Vale; SILVEIRA, Fernando Tobias; SCOFIELD, Alessandra; CAVALCANTE, Gustavo Góes
Visceral leishmaniasis is a disease whose etiological agent in Brazil is Leishmania infantum chagasi. Dogs are considered urban reservoirs of the disease, being an indicator of the human cases occurrence. The present study aimed to diagnose L. infantum chagasi infection in stray and owned dogs in Belém, Pará State, by polymerase chain reaction (PCR) and indirect immunofluorescence assay (IFA) using two different antigens. Venous blood samples from adult dogs, regardless of gender or breed, of different neighborhoods in Belém-PA, were collected in tubes with and without anticoagulant to obtain DNA and serum, respectively. These animals were divided into two groups: stray dogs captured by the Center for Zoonosis Control (Group A) and owned dogs (Group B). Sera were analyzed by IFA testing for IgG using two different antigens: 1) Bio-Manguinhos/Fiocruz antigen kit (Ag-PRO) containing promastigotes of Leishmania sp. (Complex Major-Like), 2) Instituto Evandro Chagas Antigen (Ag-AMA) consisting of amastigotes of L. infantum chagasi. The evaluation of the two antigens was performed considering positive the reactions above the 1:80 dilution. Already PCR was performed with DNA isolated from whole blood of animals and amplified with the primers RV1 and RV2. Of the 335 samples analyzed, 10.4% (35/335) were positive by IFA (Ag-PRO) and 0.9% (3/335) with the Ag-AMA. The distribution of positive samples is given as follows: Group A 14.8% (25/169) with Ag-PRO and 1.2% (2/169) with Ag-AMA; Group B 6% (10/166) with Ag-PRO and 0.6% (1/166) with Ag-AMA, being that all samples positive by IFA with Ag-AMA also reacted with Ag-PRO, and none of the samples detected DNA of L. infantum chagasi. The findings of this study indicate that Belém can still be considered non-endemic area for canine visceral leishmaniasis and the nature of the antigen influences the result of the IFA for the detection of anti-L. infantum chagasi antibodies in dogs, and the IFA using promastigotes of Leishmania major-like antigen should be used with caution as a confirmatory diagnostic on epidemiological studies in non-endemic areas.
Acesso aberto (Open Access)
Further observations on clinical, histopathological, and immunological features of borderline disseminated cutaneous leishmaniasis caused by Leishmania (Leishmania) amazonensis
(2005-08) SILVEIRA, Fernando Tobias; LAINSON, Ralph; CORBETT, Carlos Eduardo Pereira
Leishmania (Leishmania) amazonensis has for some time been considered as the causative agent of two distinct forms of American cutaneous leishmaniasis (ACL): localized cutaneous leishmaniasis (LCL), and anergic diffuse cutaneous leishmaniasis (ADCL). Recently, a new intermediate form of disease, borderline disseminated cutaneous leishmaniasis (BDCL), was introduced into the clinical spectrum of ACL caused by this parasite, and in this paper we record the clinical, histopathological, and immunological features of eight more BDCL patients from Brazilian Amazonia, who acquired the disease in the Pará state, North Brazil. Seven of them had infections of one to two years' evolution and presented with primary skin lesions and the occurrence of metastases at periods varying from six to 12 months following appearance of the first lesion. Primary skin lesions ranged from 1-3 in number, and all had the aspect of an erythematous, infiltrated plaque, variously located on the head, arms or legs. There was lymphatic dissemination of infection, with lymph node enlargement in seven of the cases, and the delayed hypersensitivity skin-test (DTH) was negative in all eight patients prior to their treatment. After that, there was a conversion of DTH to positive in five cases re-examined. The major histopathological feature was a dermal mononuclear infiltration, with a predominance of heavily parasitized and vacuolated macrophages, together with lymphocytes and plasma cells. In one case, with similar histopathology, the patient had acquired his infection seven years previously and he presented with the largest number of disseminated cutaneous lesions. BDCL shows clinical and histopathological features which are different from those of both LCL and ADCL, and there is a good prognosis of cure which is generally not so in the case of frank ADCL.
Acesso aberto (Open Access)
Severe visceral leishmaniasis in children: the relationship between cytokine patterns and clinical features
(Universidade Federal do Pará, 2013-12) GAMA, Mônica Elinor Alves; GOMES, Claudia Maria de Castro; SILVEIRA, Fernando Tobias; AURENTI, Márcia Dalastra; GONÇALVES, Eloisa da Graça do Rosario; SILVA, Antônio Rafael da; CORBETT, Carlos Eduardo Pereira
Introduction: The relationship between severe clinical manifestations of visceral leishmaniasis (VL) and immune response profi les has not yet been clarifi ed, despite numerous studies on the subject. This study aimed to investigate the relationship between cytokine profi les and the presence of immunological markers associated with clinical manifestations and, particularly, signs of severity, as defi ned in a protocol drafted by the Ministry of Health (Brazil). Methods: We conducted a prospective, descriptive study between May 2008 and December 2009. This study was based on an assessment of all pediatric patients with VL who were observed in a reference hospital in Maranhão. Results: Among 27 children, 55.5% presented with more than one sign of severity or warning sign. Patients without signs of severity or warning signs and patients with only one warning sign had the highest interferon-gamma (IFN-γ) levels, although their interleukin 10 (IL-10) levels were also elevated. In contrast, patients with the features of severe disease had the lowest IFN-γ levels. Three patients who presented with more than two signs of severe disease died; these patients had undetectable interleukin 2 (IL-2) and IFN-γ levels and low IL-10 levels, which varied between 0 and 36.8pg/mL. Conclusions: Our results showed that disease severity was associated with low IFN-γ levels and elevated IL-10 levels. However, further studies with larger samples are needed to better characterize the relationship between disease severity and cytokine levels, with the aim of identifying immunological markers of active-disease severity.
Acesso aberto (Open Access)
Susceptibility of Cebus apella monkey (Primates: Cebidae) to experimental Leishmania (L.) infantum chagasi-infection
(2011-02) CARNEIRO, Liliane Almeida; SILVEIRA, Fernando Tobias; CAMPOS, Marliane Batista; BRÍGIDO, Maria do Carmo de Oliveira; CORBETT, Carlos Eduardo Pereira; LAURENTI, Márcia Dalastra
In Amazonian Brazil, the Cebus apella monkey (Primates: Cebidae) has been associated with the enzootic cycle of Leishmania (V.) shawi, a dermotropic parasite causing American cutaneous leishmaniasis (ACL). It has also been successfully used as animal model for studying cutaneous leishmaniasis. In this work, there has been investigated its susceptibility to experimental Leishmania (L.) infantum chagasi-infection, the etiologic agent of American visceral leishmaniasis (AVL). There were used ten C. apella specimens, eight adult and two young, four males and six females, all born and raised in captivity. Two experimental infection protocols were performed: i) six monkeys were inoculated, intra-dermal via (ID), into the base of the tail with 2 x 106 promastigotes forms from the stationary phase culture medium; ii) other four monkeys were inoculated with 3 x 107 amastigotes forms from the visceral infection of infected hamsters by two different via: a) two by intravenous via (IV) and, b) other two by intra-peritoneal via (IP). The parameters of infection evaluation included: a) clinical: physical exam of abdomen, weigh and body temperature; b) parasitological: needle aspiration of the bone-marrow for searching of amastigotes (Giemsa-stained smears) and promastigotes forms (culture medium); c) immunological: Indirect fluorescence antibody test (IFAT) and, Delayed-type hypersensitivity (DTH). In the six monkeys ID inoculated (promastigotes forms) all parameters of infection evaluation were negative during the 12 months period of follow-up. Among the four monkeys inoculated with amastigotes forms, two IV inoculated showed the parasite in the bone-marrow from the first toward to the sixth month p.i. and following that they cleared the infection, whereas the other two IP inoculated were totally negative. These four monkeys showed specific IgG-antibody response since the third month p.i. (IP: 1/80 and IV: 1/320 IgG) toward to the 12th month (IP: 1/160 and IV: 1/5120). The DTH-conversion occurred in only one IV inoculated monkey with a strong (30 mm) skin reaction. Considering these results, we do not encourage the use of C. apella monkey as animal model for studying the AVL.
Acesso aberto (Open Access)
Susceptibility of peritoneal macrophage from different species of neotropical primates to Ex vivo Leishmania (L.) infantum chagasi-infection
(2012-04) CARNEIRO, Liliane Almeida; LAURENTI, Márcia Dalastra; CAMPOS, Marliane Batista; GOMES, Claudia Maria de Castro; CORBETT, Carlos Eduardo Pereira; SILVEIRA, Fernando Tobias
This study examined the susceptibility of peritoneal macrophage (PM) from the Neotropical primates: Callithrix jacchus, Callithrix penicillata, Saimiri sciureus, Aotus azarae infulatus and Callimico goeldii to ex vivo Leishmania (L.) infantum chagasi-infection, the etiological agent of American visceral leishmaniasis (AVL), as a screening assay for evaluating the potential of these non-human primates as experimental models for studying AVL. The PM-susceptibility to infection was accessed by the PM-infection index (PMI) at 24, 72 h and by the mean of these rates (FPMI), as well as by the TNF-α, IL-12 (Capture ELISA) and Nitric oxide (NO) responses (Griess method). At 24h, the PMI of A. azarae infulatus (128) was higher than those of C. penicillata (83), C. goeldii (78), S. sciureus (77) and C. jacchus (55). At 72h, there was a significant PMI decrease in four monkeys: A. azarae infulatus (128/37), C. penicillata (83/38), S. sciureus (77/38) and C. jacchus (55/12), with exception of C. goeldii (78/54). The FPMI of A. azarae infulatus (82.5) and C. goeldii (66) were higher than C. jacchus (33.5), but not higher than those of C. penicillata (60.5) and S. sciureus (57.5). The TNF-a response was more regular in those four primates which decreased their PMI at 24/72 h: C. jacchus (145/122 pg/mL), C. penicillata (154/130 pg/mL), S. sciureus (164/104 pg/mL) and A. azarae infulatus (154/104 pg/mL), with exception of C. goeldii (38/83 pg/mL). The IL-12 response was mainly prominent in A. infulatus and C. goeldii which presented the highest FPMI and, the NO response was higher in C. goeldii, mainly at 72 h. These findings strongly suggest that these New World primates have developed a resistant innate immune response mechanism capable of controlling the macrophage intracellular growth of L. (L.) i. chagasi-infection, which do not encourage their use as animal model for studying AVL.