Pharmacokinetic and parasitological evaluation of the bone marrow of dogs with visceral leishmaniasis submitted to multiple dose treatment with liposome-encapsulated meglumine antimoniate

The aim of the present study was to evaluate the impact of a multiple dose regimen of a liposomal formulation of meglumine antimoniate (LMA) on the pharmacokinetics of antimony in the bone marrow of dogs with visceral leishmaniasis and on the ability of LMA to eliminate parasites from this tissue. Dogs naturally infected with Leishmania chagasi received 4 intravenous doses of either LMA (6.5 mg antimony/kg body weight, N = 9), or empty liposomes (at the same lipid dose as LMA, N = 9) at 4-day intervals. A third group of animals was untreated (N = 8). Before each administration and at different times after treatment, bone marrow was obtained and analyzed for antimony level (LMA group) by electrothermal atomic absorption spectrometry, and for the presence of Leishmania parasites (all groups). There was a significant increase of antimony concentration from 0.76 µg/kg wet organ (4 days after the first dose) to 2.07 µg/kg (4 days after the fourth dose) and a half-life of 4 days for antimony elimination from the bone marrow. Treatment with LMA significantly reduced the number of dogs positive for parasites (with at least one amastigote per 1000 host cells) compared to controls (positive dogs 30 days after treatment: 0 of 9 in the LMA group, 3 of 9 in the group treated with empty liposomes and 3 of 8 in the untreated group). However, complete elimination of parasites was not achieved. In conclusion, the present study showed that multiple dose treatment with LMA was effective in improving antimony levels in the bone marrow of dogs with visceral leishmaniasis and in reducing the number of positive animals, even though it was not sufficient to achieve complete elimination of parasites.

Leishmania (Leishmania) chagasi-infected mice as a model for the study of glomerular lesions in visceral leishmaniasis

Renal involvement in visceral leishmaniasis (VL) is very frequent but the pathogenesis of this nephropathy is poorly understood. In previous studies using dogs with VL we have detected new immunopathological elements in the glomeruli such as T cells and adhesion molecules. Although Leishmania (Leishmania) chagasi-infected dogs and hamsters are considered to be good models for VL, their use is limited for immunopathologic studies. The use of isogenic mouse strains susceptible to L. (L.) chagasi infection was an alternative but, on the other hand, the renal lesions of these animals have not yet been characterized. Thus, our purpose in the present study was to characterize mice infected with L. (L.) chagasi as a suitable model to study VL nephropathy. Kidney samples were obtained from control mice (N = 12) and from BALB/c mice (N = 24) injected intraperitoneally with 20 million L. (L.) chagasi amastigotes 7, 15, and 30 days after injection and processed for histopathological studies and detection of IgG deposits. Glomerular hypercellularity was clearly visible and, upon Mason's trichrome and periodic acid methenamine silver staining, a pattern suggestive of mesangial proliferative glomerulonephritis was observed in mice with VL. Time-dependent IgG deposits were also seen in infected mice. We consider L. (L.) chagasi-infected mice to be a suitable model for studies of the immunopathogenesis of glomerular lesions in VL.

Dynamics of immunosuppression in hamsters with experimental visceral leishmaniasis

Immunosuppression has been reported to occur during active visceral leishmaniasis and some factors such as the cytokine profile may be involved in this process. In the mouse model of cutaneous leishmaniasis using Leishmania (Leishmania) major, the Th1 response is related to protection while the Th2 response is related to disease progression. However, in hamsters, which are considered to be an excellent model for the study of visceral leishmaniasis, this dichotomy is not observed. Using outbred 45- to 60-day-old (140 to 150 g) male hamsters infected intraperitoneally with 2 x 10(7) L. (L.) chagasi amastigotes, we evaluated the immune response of spleen cells and the production of cytokines. We used 3 to 7 hamsters per group evaluated. We detected a preserved response to concanavalin A measured by index of proliferation during all periods of infection studied, while a proliferative response to Leishmania antigen was detected only at 48 and 72 h post-infection. Messenger RNA from cytokines type 1 (IL-2, TNF-α, IFN-γ) and type 2 (IL-4, IL-10 and TGF-β) detected by reverse transcriptase polymerase chain reaction and produced by spleen cells showed no qualitative difference between control non-infected hamsters and infected hamsters during any period of infection evaluated. Cytokines were measured by the DNA band intensity on agarose gel using the Image Lab 1D L340 software with no differences observed. In conclusion, the present results showed an antigen-dependent immunosuppression in hamsters with active visceral leishmaniasis that was not related to the cytokine profile.

Observations on the feeding habits of Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae: Phlebotominae) in Campo Grande, an endemic area of visceral leishmaniasis in Mato Grosso do Sul, Brazil

Sand flies were captured weekly with CDC light traps from December 2003 to November 2005 in three areas of Campo Grande, in the Brazilian state of Mato Grosso do Sul. These areas incorporated two patches of remnant forest and five houses. The blood meals of engorged female sand flies were identified using the avidin-biotin system of immunoenzymatic ELISA capture. Most (327/355) of the females analysed were Lutzomyia longipalpis, of which 66.4% reacted with human blood, 64.8% with that of birds and 8.9% with that of dogs. Females that had taken human blood predominated in the residential areas and two forest patches. The following combinations of blood were also detected for L. longipalpis in some of the samples analysed: bird + human (43.4%), bird + human + dog (6.1%). The combination bird + human + dog + pig was also found for Nyssomyia whitmani. Dogs and pigs appear to have little attractiveness for L. longipalpis. The results obtained demonstrate the eclecticism and high anthropophily of L. longipalpis and raise new questions with regard to the importance of dogs in VL epidemiology and the possible role of man as a source of infection for sand flies. (C) 2008 Elsevier B.V. All rights reserved.

Seasonal variation of Lutzomyia longipalpis (Lutz & neiva, 1912) (Diptera : Psychodidae : Phlebotominae) in endemic area of visceral leishmaniasis, Campo Grande, state of Mato Grosso do Sul, Brazil

The seasonal distribution of Lutzomyia longipalpis was studied in two forested and five domiciliary areas of the urban area of Campo Grande; MS, from December 2003 to November 2005. Weekly captures were carried out with CDC light traps positioned on ground and in the canopy inside a residual forest and on the edge (ground) of a woodland and in at least one of the following ecotopes in peridomiciles-a cultivated area, a chicken coop, a pigsty, a kennel, a goat and sheep shelter and an intradomicile. A total of 9519 sand flies were collected, 2666 during the first year and 6853 during the second. L. longipalpis was found throughout the 2-year period, presenting smaller peaks at intervals of 2-3 months and two greater peaks, the first in February and the second in April 2005, soon after periods of heavy rain. Only In one of the woodlands was a significant negative correlation (p < 0.05) between the number of insects and temperature during the first year and the climatic factors (temperature, RHA and rain) was observed. In the domiciliary areas in four domiciles some positive correlations (p < 0.05) occurred in relation to one or more climatic factors; however, the species shows a clear tendency to greater frequency (72%) in the rainy season than in the dry (28%). Thus, we recommend an intensification of the VL control measures applied in Campo Grande, MS, during the rainy season with a view to reducing the risk of the transmission of the disease. (C) 2007 Elsevier B.V. All fights reserved.

Genetic and Functional Evidence Implicating DLL1 as the Gene That Influences Susceptibility to Visceral Leishmaniasis at Chromosome 6q27

Background. Visceral leishmaniasis (VL) is caused by Leishmania donovani and Leishmania infantum chagasi. Genome-wide linkage studies from Sudan and Brazil identified a putative susceptibility locus on chromosome 6q27. Methods. Twenty-two single-nucleotide polymorphisms (SNPs) at genes PHF10, C6orf70, DLL1, FAM120B, PSMB1, and TBP were genotyped in 193 VL cases from 85 Sudanese families, and 8 SNPs at genes PHF10, C6orf70, DLL1, PSMB1, and TBP were genotyped in 194 VL cases from 80 Brazilian families. Family-based association, haplotype, and linkage disequilibrium analyses were performed. Multispecies comparative sequence analysis was used to identify conserved noncoding sequences carrying putative regulatory elements. Quantitative reverse-transcription polymerase chain reaction measured expression of candidate genes in splenic aspirates from Indian patients with VL compared with that in the control spleen sample. Results. Positive associations were observed at PHF10, C6orf70, DLL1, PSMB1, and TBP in Sudan, but only at DLL1 in Brazil (combined P = 3 x 10(-4) at DLL1 across Sudan and Brazil). No functional coding region variants were observed in resequencing of 22 Sudanese VL cases. DLL1 expression was significantly (P = 2 x 10(-7)) reduced (mean fold change, 3.5 [SEM, 0.7]) in splenic aspirates from patients with VL, whereas other 6q27 genes showed higher levels (1.27 x 10(-6) < P < .01) than did the control spleen sample. A cluster of conserved noncoding sequences with putative regulatory variants was identified in the distal promoter of DLL1. Conclusions. DLL1, which encodes Delta-like 1, the ligand for Notch3, is strongly implicated as the chromosome 6q27 VL susceptibility gene.

Density of sand flies (diptera: psychodidae) in domestic and wild animal shelters in an area of visceral leishmaniasis in the state of Rio Grande do Norte, Brazil

XIMENES, Maria de Fátima Freire de Melo; SOUZA, Maria de Fátima de; CASTELLON, Eloy Guilhermo. Density of sand flies (Diptera: Psychodidae) in domestic and wild animal shelters in an area of visceral Leishmaniasis in the State of Rio Grande do Norte, Brazil. Memorias do Instituto Oswaldo Cruz, Rio de Janeiro, v.94, n.4, p.427-432, jul./ago. 1999. Disponivel em: Acesso em: 4 out. 2010.

Immune response pattern of the popliteal lymph nodes of dogs with visceral leishmaniasis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

VISCERAL LEISHMANIASIS IN A CAPTIVE CRAB-EATING FOX CERDOCYON THOUS

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sandfly fauna in an area endemic for visceral leishmaniasis in Aracaju, State of Sergipe, Northeast Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Surveillance of canine visceral leishmaniasis in a disease-free area

A leishmaniose é uma importante parasitose re-emergente observada no mundo, particularmente em países tropicais. Não há ainda relatos de casos autóctones no estado do Paraná. Não há até o momento referência de vigilância no reservatório canino, tais como Curitiba e região metropolitana do estado. O objetivo do estudo foi determinar a soroprevalência da leishmaniose visceral em cães entregues ao Centro de Controle de Zoonoses de São José dos Pinhais, Paraná para eutanásia. A detecção sorológica da presença de anticorpos contra Leishmania sp. foi realizada por (ELISA) indireto e pela Reação de Imunofluorescência Indireta (RIFI). Além disso, impressão de linfonodo poplíteo coletadas ao acaso de 50 cães com sinais clínicos suspeitos para leishmaniose visceral e analisados sob microscopia óptica para detecção de formas amastigotas, foram negativas. Amostras de soro de 364 animais foram testadas, e os resultados mostraram somente uma amostra positiva (0,0027%), reagente ao ELISA e negativa à RIFI, entretanto, o cão não apresentava sinais clínicos. A vigilância ao acaso em uma população de vários locais de uma área metropolitana pode ser uma forma de prevenção da disseminação da doença. Com base nos resultados observados, Curitiba e região metropolitana foram consideradas de baixo risco para a leishmaniose visceral.

Active surveillance of canine visceral leishmaniasis and american trypanossomiasis in rural dogs from non endemic area

A leishmaniose visceral canina (LVC) e a tripanossomíase americana são importantes zoonoses para a saúde pública que encontram no cão o principal reservatório doméstico para o homem. O trabalho procurou estimar a prevalência de anticorpos circulantes anti-Trypanosoma cruzi e anti-Leishmania spp., em amostras de cães provenientes da zona rural do município de Botucatu, SP. Durante a campanha de vacinação antirrábica canina da zona rural do município, foram coletadas 689 amostras de soro e processadas pela técnica de imunofluorescência indireta. Os testes sorológicos revelaram a ausência de anticorpos anti-Leishmania spp. e, na pesquisa dos anticorpos anti-T. cruzi, foram detectados 3 (0,4%) cães.

Coinfection of Leishmania chagasi with Toxoplasma gondii, Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV) in cats from an endemic area of zoonotic visceral leishmaniasis

The aim of the present study was to determine the coinfection of Leishmania sp. with Toxoplasma gondii, Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV) in a population of cats from an endemic area for zoonotic visceral leishmaniasis. An overall 66/302 (21.85%) cats were found positive for Leishmania sp., with infection determined by direct parasitological examination in 30/302(9.93%), by serology in 46/302(15.23%) and by both in 10/302 (3.31%) cats. Real time PCR followed by amplicon sequencing successfully confirmed Leishmania infantum (syn Leishmania chagasi) infection. Out of the Leishmania infected cats, coinfection with FIV was observed in 12/66(18.18%), with T. gondii in 17/66 (25.75%) and with both agents in 5/66(7.58%) cats. FeLV was found only in a single adult cat with no Leishmania infection. A positive association was observed in coinfection of Leishmania and FIV (p < 0.0001), but not with T. gondii (p > 0.05). In conclusion, cats living in endemic areas of visceral leishmaniasis are significantly more likely to be coinfected with Fly, which may present confounding clinical signs and therefore cats in such areas should be always carefully screened for coinfections. (C) 2012 Elsevier B.V. All rights reserved.

Performance of IFAT, ELISA, direct parasitological examination and PCR on lymph node aspirates for canine visceral leishmaniasis diagnosis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Leishmania spp. and/or Trypanosoma cruzi diagnosis in dogs from endemic and nonendemic areas for canine visceral leishmaniasis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)