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Visceral leishmaniasis caused by the protozoan Leishmania infantum is a zoonosis. The domestic dog is the primary reservoir in urban areas. This study aimed to evaluate the frequency, active infection and load of L. infantum in the genital tract of male and female dogs seropositive for this parasite, as well as to identify histological genital alterations associated with this protozoan. We studied 45 male and 25 female L. infantum-seropositive noncastrated dogs from the same endemic area in Brazil. Tissue samples from the testis, epididymis, prostate, vulva, vagina, and uterus were examined by singleplex qPCR and parasitological tests (histopathology, immunohistochemistry, and parasitological culture). The latter were performed for the detection of active infection (parasites able to multiply and to induce lesions). Forty-four (98%) males and 25 (100%) females were positive for L. infantum in the genital tract (epididymis: 98%; vulva: 92%; vagina: 92%; testis: 91%; uterus: 84%; prostate: 66%). Active infection in the genital tract was confirmed in 69% of males and 64% of females (32% in the uterus). Parasite loads were similar in the testis, vulva, epididymis and vagina and lower in the prostate. Only the parasite load in the vagina was significantly associated with the number of clinical signs. Granulomatous inflammation predominated in all organs, except for the prostate. Only in the testis and epididymis was the inflammatory infiltrate significantly more intense among dogs with a higher parasite load in these organs. The high frequency, detection of active infection and similarity of L. infantum loads in the genital tract of infected males and females suggest the potential of venereal transmission of this parasite by both sexes and of vertical transmission by females in the area studied. Additionally, vertical transmission may be frequent since active L. infantum infection was a common observation in the uterus.

In Brazil, visceral leishmaniasis (VL) has spread to various regions. This study reports canine cases of VL in Barra Mansa, where human VL cases were recently reported. Using the human index case, a canine survey was performed by dual-path platform immunochromatography and enzyme-linked immunosorbent assay. Seropositive animals were euthanized. Cultures were collected to detect Leishmania parasites. Serological tests detected 141 canine VL cases, and Leishmania chagasi were isolated from 82.2% animals. Leishmania chagasi is in circulation in Barra Mansa. This study broadens information on the parasite's distribution in the State of Rio de Janeiro.

The objective of the current research was to assess seroconversion in dogs immunized with Leishmune® and Leish Tec® vaccines using rapid chromatographic immunoassay DPP® (Dual Path Platform) (DPP CVL) and enzyme immunoassay (EIE) up to one year after the vaccination protocol. The study sample comprised 28 dogs divided into two groups, each group immunized with an anti-CVL vaccine and clinically monitored for one year through clinical evaluation and laboratory tests. 22 (78.5%) dog were monitored. During the evaluation time (T1-30 days, T2-6 months, and T3-1 year after vaccination) the results for all dogs were negative for CVL, except for one animal vaccinated with Leish tec® that seroconverted in the DPP CVL test at T2. Subsequent examinations of this dog were negative. Our results showed that in a non-endemic area, even at different evaluation times, dogs vaccinated against CVL with Leishmune® or Leish tec® did not seroconvert in the serological protocol used by the Brazilian Ministry of Health (DPP/EIE). RESUMO: O objetivo deste trabalho foi avaliar a soroconversão em cães imunizados com as vacinas Leishmune® e Leish tec®, através do teste imunocromatográfico rápido DPP® (Dual Path Platform) (DPP LVC) e do ensaio imunoenzimático (EIE) durante um ano após o protocolo vacinal. Trata-se de um estudo onde 28 cães divididos em dois grupos foram imunizados cada um com uma vacina anti - LVC e acompanhados durante um ano através de avaliação clínica e exames laboratoriais. Foi possível acompanhar 22 (78.5%) cães. Nos exames dos tempos 1, 2 e 3 (respectivamente 30 dias, 6 messes e 1 ano após a vacinação) os resultados de todos os cães também foram negativos para LVC, exceto de um cão que recebeu a vacina Leish tec® e soroconverteu no DPP LVC no T2, após 6 meses a vacina. Os exames posteriores deste cão foram negativos. Os resultados do presente estudo demostraram que, em área não endêmica e mesmo em diferentes tempos de avaliação, cães vacinados contra LVC, independente da vacina utilizada, não foram capazes de soroconverter no protocolo utilizado pelo Ministério da Saúde brasileiro (DPP/EIE).

Trypanosoma caninum is a protozoan species recently described in dogs, whose occurrence has been reported in areas of overlap with visceral leishmaniasis. Trypanosoma sp. were isolated from nine dogs and characterized by molecular methods. PCR and sequencing confirmed the presence of T. caninum in all dogs, revealing two new areas of transmission: Barra Mansa and São João do Piauí. The nine new cases described, when added to those already published, account for 62 cases of natural infection by T. caninum and show the geographical spread of this species to new areas, where other trypanosomatids circulate.

In Brazil, Leishmania (Leishmania) infantum causes canine visceral leishmaniasis; the primary vector is the Lutzomyia longipalpis sand fly. We describe a case of canine visceral leishmaniasis caused by Leishmania (Viannia) lainsoni in a dog from Barra Mansa municipality, Rio de Janeiro state. Better specificity of serologic diagnostic techniques is needed for diagnoses.

Chagas disease and the leishmaniases are endemic zoonoses of great importance to public health in the state of Piauí, Brazil. The domestic dog (Canis familiaris) is a major reservoir, host of Trypanosoma cruzi and Leishmania spp. in both urban and rural areas, playing an important role in the transmission of these parasites. The present study evaluated the prevalence of both infectious diseases in dogs of a rural area in the municipality of São João do Piauí, Piauí State. One hundred twenty-nine blood samples were collected for serological assessment: for the leishmaniases, 49 (38%) animals tested positive by the Dual-Path Platform technology (DPP), nine (6%) by the Enzyme-linked Immunosorbent Assay (ELISA), and 19 (14.7%) by the Indirect Fluorescent Antibody test (IFA); while for American Trypanosomiasis, 36 (28%) dogs were reagent by ELISA and 21 by IFA. Of the 129 dogs sampled, 76 were submitted to xenodiagnosis, bone marrow aspiration and skin biopsy to perform parasitological tests whose results showed only one (2.3%) positive skin sample for Trypanosoma caninum and one positive xenodiagnosis for T. cruzi, both results confirmed by molecular assays. Three hundred triatomines of the species Triatoma brasiliensis and 552 phlebotomines - 509 (97%) of the species Lutzomyia longipalpis, were also captured.

In canine visceral leishmaniasis (CVL), splenic white pulp (SWP) disorganization has been associated with disease progression, reduced cytokine and chemokine expression and failure to control the parasite load. This profile is compatible with the cellular exhaustion previously shown in human visceral leishmaniasis. The present study aimed to evaluate the in situ expression of cellular exhaustion markers and their relation to clinical signs, SWP disorganization and parasite load. Forty dogs naturally infected by Leishmania infantum were grouped according to levels of SWP organization and parasite load. SWP disorganization was associated with reductions in the periarteriolar lymphatic sheath and lymphoid follicles/mm 2 and worsening of the disease. Apoptotic cells expressing CTLA-4 + increased in dogs with disorganized SWP and a high parasite load. In the same group, PD-L1 and LAG-3 gene expression were reduced. A higher number of CD21 + TIM-3 + B cells was detected in disorganized spleens than in organized spleens. Apoptosis is involved in periarteriolar lymphatic sheath reduction and lymphoid follicle atrophy and is associated with CTLA-4 + cell reductions in the splenic tissue of dogs with visceral leishmaniasis (VL). Failure to control the parasite load was observed, suggesting that cell exhaustion followed by T and B cell apoptosis plays a role in the immunosuppression observed in CVL.

Zoonotic visceral leishmaniasis is caused by the protozoan Leishmania infantum and little is known about the occurrence and pathogenesis of this parasite in the CNS. The aims of this study were to evaluate the occurrence, viability and load of L. infantum in the CNS, and to identify the neurological histological alterations associated with this protozoan and its co-infections in naturally infected dogs. Forty-eight Leishmania-seropositive dogs from which L. infantum was isolated after necropsy were examined. Cerebrospinal fluid (CSF) samples were analyzed by parasitological culture, quantitative real-time PCR (qPCR) and the rapid immunochromatographic Dual Path Platform test. Brain, spinal cord and spleen samples were submitted to parasitological culture, qPCR, and histological techniques. Additionally, anti-Toxoplasma gondii and anti-Ehrlichia canis antibodies in serum and distemper virus antigens in CSF were investigated. None of the dogs showed neurological signs. All dogs tested positive for L. infantum in the CNS. Viable forms of L. infantum were isolated from CSF, brain and spinal cord in 25% of the dogs. Anti-L. infantum antibodies were detected in CSF in 61% of 36 dogs. Inflammatory histological alterations were observed in the CNS of 31% of the animals; of these, 66% were seropositive for E. canis and/or T. gondii. Amastigote forms were associated with granulomatous non-suppurative encephalomyelitis in a dog without evidence of co-infections. The highest frequency of L. infantum DNA was observed in the brain (98%), followed by the spinal cord (96%), spleen (95%), and CSF (50%). The highest L. infantum load in CNS was found in the spinal cord. These results demonstrate that L. infantum can cross the blood-brain barrier, spread through CSF, and cause active infection in the entire CNS of dogs. Additionally, L. infantum can cause inflammation in the CNS that can lead to neurological signs with progression of the disease.

Zoonotic visceral leishmaniasis is caused by Leishmania (Leishmania) infantum and dogs are the main domestic reservoir. This study compared the performance of parasitological tests using semi-automatic needle puncture (SANP) for collecting popliteal lymph node samples with samples collected from the same lymph node by fine needle aspiration puncture (FNAP) and by necropsy for the diagnosis of canine visceral leishmaniasis (CVL). Popliteal lymph node samples were collected from 30 CVL-seropositive dogs from an endemic region in Brazil. After clinical examination and euthanasia, samples were collected from the same lymph node by SANP, FNAP, and necropsy. The reference tests were culture, immunohistochemistry, and histopathology. Positivity for Leishmania spp. was 70% for immunohistochemistry and 33.3% for histopathology. Culture positivity using the different sampling techniques was 77% for necropsy (87% in the first week), 73% for FNAP (82% in the first week), and 63% for SANP (95% in the first week). The combination of SANP and culture proved to be an alternative for the diagnosis of Leishmania spp. in the lymph node samples of dogs because of its high positivity rate and because it is more practical and faster and has a shorter time to positivity by culture when compared to FNAP and necropsy sampling.

Infection by SARS-CoV-2 in domestic animals has been related to close contact with humans diagnosed with COVID-19. Objectives: To assess the exposure, infection, and persistence by SARS-CoV-2 of dogs and cats living in the same households of humans that tested positive for SARS-CoV-2, and to investigate clinical and laboratory alterations associated with animal infection. Animals living with COVID-19 patients were longitudinally followed and had nasopharyngeal/oropharyngeal and rectal swabs collected and tested for SARS-CoV-2. Additionally, blood samples were collected for laboratory analysis, and plaque reduction neutralization test (PRNT90) to investigate specific SARS-CoV-2 antibodies. Between May and October 2020, 39 pets (29 dogs and 10 cats) of 21 patients were investigated. Nine dogs (31%) and four cats (40%) from 10 (47.6%) households were infected with or seropositive for SARS-CoV-2. Animals tested positive from 11 to 51 days after the human index COVID-19 case onset of symptoms. Three dogs tested positive twice within 14, 30, and 31 days apart. SARS-CoV-2 neutralizing antibodies were detected in one dog (3.4%) and two cats (20%). In this study, six out of thirteen animals either infected with or seropositive for SARS-CoV-2 have developed mild but reversible signs of the disease. Using logistic regression analysis, neutering, and sharing bed with the ill owner were associated with pet infection. The presence and persistence of SARS-CoV-2 infection have been identified in dogs and cats from households with human COVID-19 cases in Rio de Janeiro, Brazil. People with COVID-19 should avoid close contact with their pets during the time of their illness.