Parasite Detection in Visceral Leishmaniasis Samples by Dye-Based qPCR Using New Gene Targets of Leishmania infantum and Crithidia.

Visceral leishmaniasis (VL) is a neglected disease considered a serious public health problem, especially in endemic countries. Several studies have discovered monoxenous trypanosomatids (Leptomonas and Crithidia) in patients with VL. In different situations of leishmaniasis, investigations have examined cases of co-infection between Leishmania spp. and Crithidia spp. These coinfections have been observed in a wide range of vertebrate hosts, indicating that they are not rare. Diagnostic techniques require improvements and more robust tools to accurately detect the causative agent of VL. This study aimed to develop a real-time quantitative dye-based PCR (qPCR) assay capable of distinguishing Leishmania infantum from Crithidia-related species and to estimate the parasite load in samples of VL from humans and animals. The primer LinJ31_2420 targets an exclusive phosphatase of L. infantum; the primer Catalase_LVH60-12060_1F targets the catalase gene of Crithidia. Therefore, primers were designed to detect L. infantum and Crithidia sp. LVH60A (a novel trypanosomatid isolated from VL patients in Brazil), in samples related to VL. These primers were considered species-specific, based on sequence analysis using genome data retrieved from the TriTryp database and the genome assembling of Crithidia sp. LVH60A strain, in addition to experimental and clinical data presented herein. This novel qPCR assay was highly accurate in identifying and quantifying L. infantum and Crithidia sp. LVH60A in samples obtained experimentally (in vitro and in vivo) or collected from hosts (humans, dogs, cats, and vectors). Importantly, the screening of 62 cultured isolates from VL patients using these primers surprisingly revealed that 51 parasite cultures were PCR+ for Crithidia sp. In addition, qPCR assays identified the co-infection of L. infantum with Crithidia sp. LVH60A in two new VL cases in Brazil, confirming the suspicion of co-infection in a previously reported case of fatal VL. We believe that the species-specific genes targeted in this study can be helpful for the molecular diagnosis of VL, as well as for elucidating suspected co-infections with monoxenous-like trypanosomatids, which is a neglected fact of a neglected disease.

Feline leishmaniosis: hematological and biochemical analysis.

One hundred and sixty-six cats from two animal shelters were subjected to enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence antibody test (IFAT), conventional polymerase chain reaction (cPCR), quantitative PCR (qPCR) and parasitological tests (PA) for the diagnosis of Leishmania spp. Among them, 15% (25/166), 53.6% (89/166), 3.6% (06/166) and 1.8% (03/166) were positive by ELISA, IFAT, both PCRs and PA, respectively. The sequencing of ITS-1 PCR amplicons revealed a 100% match with Leishmania infantum. After the Leishmania spp. survey, 12 cats were selected and divided into two groups for clinical, hematological, and biochemical analysis: six L. infantum positive cats (G1) and six Leishmania spp. negative cats (G2). All the cats were negative for feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV). A statistical analysis indicated significantly low platelet counts and significant hyperproteinemia associated with hypoalbuminemia in positive cats (p<0.05). Our results suggest that in endemic areas, cats with clinical signs of feline leishmaniosis (such as skin lesions, weight loss and/or enlarged lymph nodes) and that exhibit hematological and biochemical changes, such as low platelet counts and hyperproteinemia with hypoalbuminemia, should be tested for Leishmania spp. infection.

Use of the intradermal leishmanin test (Montenegro skin test) for feline visceral leishmaniosis: Detection of cellular immunity.

This study evaluated the humoral and cellular response in 100 cats living in an endemic area of visceral leishmaniosis (VL) using the Montenegro Skin Test (MST) and serological diagnosis and compared the MST with other diagnostic techniques. Sixty 60%, (60/100) cats were positive for MST and the diameter of positive skin reactions ranged from 5 to 9 mm. By serological methods, 74% (74/100) and 34% (34/100) had antibodies against Leishmania spp. by Immunofluorescence Antibody Test (IFAT) and Indirect Enzyme-Linked Immunosorbent Assay (ELISA), respectively. Comparing tests, the observed profiles were (1) IFAT (+)/MST (-) = 27 cats, (2) IFAT(-)/MST(+) = 13 cats, (3) IFAT(+)/MST(+) = 47 cats, (4) ELISA(+)/MST(-) = 12 cats, (5) ELISA(-)/MST(+) = 38 cats and (6) ELISA(+)/MST(+) = 22 cats. Through the combination of serological diagnosis and MST, a positivity frequency of 87% (87/100) by IFAT + MST and 72% (72/100) by ELISA + MST was identified in this cat population. Five cats (5%) were positive for Leishmania donovani complex DNA by molecular analysis, and two cats (2%) had Leishmania spp. amastigotes in lymph node smears. Therefore, the agreement between tests was classified as poor for all tests by Kappa index. The IFAT (+)/MST (+) response was the most frequent considering all cats (47%; 47/100); nonetheless, the most frequent immune expression in Polymerase Chain Reaction (PCR)-positive cats was the IFAT (+)/MST (-) profile (80%; 4/5). Five sick and PCR-positive cats, negative for Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV), that PCR sequencing matched 100% with L. donovani complex, all but one were MST negative. These results suggest that cats develop a significant cellular response against infection by parasites of the L. donovani complex, and most PCR and parasitological positive cats may be unable to develop a significant cellular response.

Xenodiagnosis in four domestic cats naturally infected by Leishmania infantum.

Leishmaniasis is a neglected tropical disease that continues to pose a serious public health problem. Albeit dogs have long been held as the major reservoirs of Leishmania infantum, the involvement of domestic cats in the zoonotic cycle of visceral leishmaniasis has gained prominence. Here, 240 cats were evaluated by clinical signs and haematological/biochemical changes compatible with leishmaniasis and were diagnosed by serological, molecular, and parasitological techniques. Thus, four cats naturally infected by L. infantum were submitted to xenodiagnosis. A total of 203 females of Lutzomyia longipalpis were subjected to feeding on four cats, with all females completing the blood meal. Parasitological and molecular assays were carried out to evaluate the presence of L. infantum in the sand flies' midgut. Promastigotes were observed in 10 females (6.5%) that fed on one cat, and L. infantum DNA was detected in 17 (8.4%) females that fed on two cats. Our results strengthen the evidence that naturally infected cats are capable of transmitting L. infantum to sand flies.

Natural infection of Lutzomyia longipalpis (Cembrene-1 population) with Leishmania infantum in a new visceral leishmaniasis focus in the eastern region of São Paulo State, Brazil.

INTRODUCTION: Visceral leishmaniasis (VL) transmission has been associated with two different populations of the Lutzomyia longipalpis complex in São Paulo state. METHODS: In a recent focus of VL, we captured and dissected sand flies and investigated Leishmania infantum infection by parasitological, PCR, and sequencing analysis. RESULTS: Flagellates were observed in 2 of 47 (4.2%) cembrene-1 Lu. longipalpis females. The sequences obtained matched those of Le. infantum. CONCLUSIONS: We found that the transmission of Le. infantum by cembrene-1 females may occur at a high rate in this focus of VL and presented new data on the vector capacity of this population.

Detection of Leishmania infantum DNA in blood samples of horses (Equus caballus) and donkeys (Equus asinus) by PCR.

Visceral leishmaniasis (VL) is a neglected tropical disease caused by the Leishmania infantum parasite. The protozoan is able to infect several domestic and wild mammals. Since the first report on Leishmania spp. infection in horses in South America, leishmaniasis in equids has been highlighted in Brazil. A molecular epidemiological survey was carried out to verify the occurrence of Leishmania spp. DNA in horses and donkeys, in leishmaniases endemic areas in Sao Paulo State, Brazil. To this end, blood samples were obtained from 107 horses and 36 donkeys and subjected to DNA extraction followed by PCR targeting the ITS-1 region. Among the horses and donkeys, 1.87% (2/107) and 8.33% (3/36) were positive by PCR, respectively. The DNA sequencing of the ITS-1 amplification products confirmed L. infantum DNA in these animals. Our results suggest that horses and donkeys from non-VL and VL endemic areas of São Paulo State may be infected by the parasite.

Leishmania infantum in the reproductive organs of dogs / Leishmania infantum em órgãos reprodutivos de cães

ABSTRACT: Leishmania infantum causes canine leishmaniasis. Using parasitological and molecular analyses, we identified L. infantum in the reproductive organs of male and female dogs. Using histochemistry, immunohistochemistry, and PCR, we examined tissue samples from the reproductive organs of 8 male dogs and 16 female dogs diagnosed with leishmaniasis. Despite the absence of macroscopic or microscopic lesions in these organs, we observed L. infantum amastigotes in tissue samples from the testis and the uterus. PCR and sequencing of these tissues revealed sequences that matched 100% with L. infantum DNA available at GenBank. The presence of L. infantum amastigotes and DNA in testicular and uterine tissue samples suggested that these organs can harbor the parasite without associated macroscopic or microscopic lesions, and this can be especially important in the vertical and venereal transmission of leishmaniasis in dogs.

RESUMO: Leishmania infantum é agente etiológico da leishmaniose canina. Por meio de análises parasitológicas e moleculares, a presença do parasita foi investigada em órgãos reprodutivos de cães machos e fêmeas. Amostras de tecidos dos órgãos reprodutivos de 8 cães machos e 16 fêmeas diagnosticados com leishmaniose foram avaliadas por histoquímica, imunohistoquímica e PCR. Apesar de não terem sido observadas lesões macroscópicas ou microscópicas nos órgãos reprodutivos desses cães, formas amastigotas de L. infantum foram observadas em amostras teciduais do testículo e útero. A PCR e o sequenciamento do DNA extraído desses tecidos revelaram sequências 100% idênticas a L. infantum depositadas no GenBank. Nossos resultados sugerem que os testículos e o útero podem abrigar o parasita, sem associação com lesões macroscópicas ou microscópicas, o que pode ter uma grande importância na transmissão venérea e vertical da leishmaniose entre cães.

Natural infection of Lutzomyia longipalpis (Cembrene-1 population) with Leishmania infantum in a new visceral leishmaniasis focus in the eastern region of São Paulo State, Brazil

Abstract INTRODUCTION Visceral leishmaniasis (VL) transmission has been associated with two different populations of the Lutzomyia longipalpis complex in São Paulo state. METHODS In a recent focus of VL, we captured and dissected sand flies and investigated Leishmania infantum infection by parasitological, PCR, and sequencing analysis. RESULTS Flagellates were observed in 2 of 47 (4.2%) cembrene-1 Lu. longipalpis females. The sequences obtained matched those of Le. infantum. CONCLUSIONS We found that the transmission of Le. infantum by cembrene-1 females may occur at a high rate in this focus of VL and presented new data on the vector capacity of this population.

DNA extraction from individual Phlebotomine sand flies (Diptera: Psychodidae: Phlebotominae) specimens: Which is the method with better results?

Phlebotomine sand flies (Diptera: Psychodidae: Phlebotominae) are a group of small insects of great concern for Public Health. These dipterous are intensely studied worldwide due to their involvement in the transmission of several pathogens, mainly Leishmania spp. parasites. Nowadays, the molecular tools have been included in Phlebotomine sand flies studies and has shown to be powerful tools in bioecology studies of these dipterous. Thereby, when molecular approaches are employed, there is a great concern regarding the amount and quality of the DNA obtained for analysis. Here, seven methods of DNA extraction, between commercial kits and in house extraction protocols were evaluated. We considered measure of DNA concentration and purity ratios using a spectrophotometer to check the performance of each protocol. In addition, the quality evaluation of the DNA extracted was performed by endogenous gene PCR on samples. The results of the seven evaluated DNA extraction protocols and their implications are discussed.

Leishmaniasis in cat shelters: A serological, molecular and entomological study.

An epidemiological Leishmania spp. and entomological Phlebotomine sandflies survey was performed in cat shelters at leishmaniasis endemic area of Brazil. Blood and conjunctival swab (CS) samples were collected from 94 cats in two animal protection shelters. These samples were subjected to serological tests using the indirect immunofluorescence antibody test (IFAT) and indirect enzyme-linked immunosorbent assay (ELISA) and to molecular test by polymerase chain reaction (PCR). In addition, a Phlebotomine sandflies survey was performed in the same shelters. The analyses revealed a positivity of 31.91% (30/94) through ELISA and 29.79% (28/94) through IFAT. The two serological tests showed a positive association with perfect agreement (k = 0.925). None of the cats were positive by Leishmania spp. DNA. One Lutzomyia (Lutzomyia) longipalpis male was found in one of the cat shelters. The results and the implications of our findings are discussed below.

Molecular detection of Leishmania spp. in cattle from Brazil by means of PCR using internal transcribed spacer 1.

Leishmania spp. are important agents of human and animal leishmaniases that have an important impact on public health. In this study, we aimed to detect the circulation of Leishmania spp. in cattle from a visceral leishmaniasis non-endemic area of the state of São Paulo, Brazil. DNA was extracted from blood samples from 100 heifers in the municipality of Pirassununga and was amplified using primers specific for the first internal transcriber spacer (ITS1), to assess the presence of trypanosomatids. The assays revealed that one sample presented bands of between 300 and 350 base pairs. In GenBank, this sample matched 100% with Leishmania infantum (314 base pairs). The results suggest that cattle can be infected by Leishmania infantum in Brazil.

Molecular detection of Leishmania infantum DNA according to clinical stages of leishmaniasis in dog.

The aim of this study was to compare molecular tests used to diagnose Leishmania spp. in dogs with different stages of infection. Blood and conjunctival swab (CS) samples from dogs classified in four clinical stages were subjected to different PCR protocols (13A/13B, MC1/MC2, LITSR/L5.8S and LEISH-1/LEISH-2 primers). To the study, 22.3% (48/215) of dogs were classified as without clinical signs, 67.5% (145/215) stage I (mild disease), 7.0% (15/215) stage II (moderate disease) and 3.2% (7/215) stage III (severe disease). The results showed that in blood samples, 13A/13B detected a significant higher number of positive dogs in stage I (25/145) and in total (42/215) (p≤0.05). However, when CS samples were tested, no difference was observed (p>0.05). On the other hand, in blood samples, MC1/MC2 detected significantly fewer positive dogs classified as without clinical signs (0/48), in stage I (0/145) and in total (1/215) (p≤0.05). Likewise, in CS samples, this primers showed also lower detection (1/215) (p≤0.05). So than, we can conclude that PCR on blood samples with 13A/13B primers has greater capacity to detect positive dogs, mainly at the initial of clinical disease than do other primers and MC1/MC2 are not a good choice to detect Leishmania infantum infection in dogs.

Molecular detection of Leishmania spp. in cattle from Brazil by means of PCR using internal transcribed spacer 1 / Detecção molecular de Leishmania spp. em gado no Brasil por PCR com espaçador interno transcrito 1

Abstract Leishmania spp. are important agents of human and animal leishmaniases that have an important impact on public health. In this study, we aimed to detect the circulation of Leishmania spp. in cattle from a visceral leishmaniasis non-endemic area of the state of São Paulo, Brazil. DNA was extracted from blood samples from 100 heifers in the municipality of Pirassununga and was amplified using primers specific for the first internal transcriber spacer (ITS1), to assess the presence of trypanosomatids. The assays revealed that one sample presented bands of between 300 and 350 base pairs. In GenBank, this sample matched 100% with Leishmania infantum (314 base pairs). The results suggest that cattle can be infected by Leishmania infantum in Brazil.

Resumo Leishmania spp. são agentes causadores das leishmanioses em humanos e em animais, gerando grande impacto à saúde pública. Este estudo objetivou detectar a circulação de Leishmania spp. em área não endêmica para leishmaniose visceral de São Paulo, Brasil. Foram extraídas amostras de DNA de 100 novilhas da cidade de Pirassununga. Estas amostras foram amplificadas com os iniciadores específicos para tripanosomatídeos Internal Transcriber Spacer 1 (ITS1). Os ensaios revelaram uma amostra com bandas entre 300 e 350 pares de base (pb). A amostra demonstrou 100% de identidade com Leishmania infantum (314 pb). Os resultados sugerem que o gado pode ser infectado por L. infantum no Brasil.

Molecular detection of Leishmania infantum DNA according to clinical stages of leishmaniasis in dog / Deteção molecular de DNA de Leishmania infantum em diferentes estágios clínicos da leishmaniose em cães

Abstract The aim of this study was to compare molecular tests used to diagnose Leishmania spp. in dogs with different stages of infection. Blood and conjunctival swab (CS) samples from dogs classified in four clinical stages were subjected to different PCR protocols (13A/13B, MC1/MC2, LITSR/L5.8S and LEISH-1/LEISH-2 primers). To the study, 22.3% (48/215) of dogs were classified as without clinical signs, 67.5% (145/215) stage I (mild disease), 7.0% (15/215) stage II (moderate disease) and 3.2% (7/215) stage III (severe disease). The results showed that in blood samples, 13A/13B detected a significant higher number of positive dogs in stage I (25/145) and in total (42/215) (p≤0.05). However, when CS samples were tested, no difference was observed (p>0.05). On the other hand, in blood samples, MC1/MC2 detected significantly fewer positive dogs classified as without clinical signs (0/48), in stage I (0/145) and in total (1/215) (p≤0.05). Likewise, in CS samples, this primers showed also lower detection (1/215) (p≤0.05). So than, we can conclude that PCR on blood samples with 13A/13B primers has greater capacity to detect positive dogs, mainly at the initial of clinical disease than do other primers and MC1/MC2 are not a good choice to detect Leishmania infantum infection in dogs.

Resumo O objetivo deste estudo foi comparar testes moleculares usados para diagnosticar Leishmania spp., em cães apresentando diferentes estágios de infecção. Amostras de sangue e suabe conjuntival (SC) de cães classificados em quatro estágios clínicos foram submetidas a diferentes PCRs (primers 13A/13B, MC1/MC2, LITSR/L5.8S e LEISH-1/LEISH-2). Para o estudo, 22,3% (48/215) dos cães foram classificados como sem sinais clínicos, 67,5% (145/215) estágio I (doença leve), 7,0% (15/215) estágio II (doença moderada) e 3,2% (7/215) estágio III (doença grave). Os resultados mostraram que, em amostras de sangue, 13A/13B detectou número significativamente maior de cães positivos no estágio I (25/145) e no total (42/215) (p≤0,05). No entanto, quando as amostras de SC foram testadas, nenhuma diferença foi observada (p>0,05). Por outro lado, no sangue, MC1/MC2 detectou significativamente menos cães positivos sem sinais clínicos (0/48), em estágio I (0/145) e no total (1/215) (p≤0,05). Da mesma forma, em amostras de SC, MC1/MC2 também apresentou menor detecção (1/215) (p≤0,05). Assim, a PCR em amostras de sangue com 13A/13B tem maior capacidade de detectar cães positivos, principalmente no início da doença do que outros primers, e o par de primers MC1/MC2 não é uma boa escolha para detectar infecção por Leishmania infantum em cães.