Genetic analysis of leishmania parasites in Ecuador: are Leishmania (Viannia) panamensis and Leishmania (V.) Guyanensis distinct taxa?
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In the course of an epidemiologic survey in Ecuador, the following collection of Leishmania stocks was isolated: 28 from patients with clinical signs of leishmaniasis, 2 from sloths, 1 from a dog, and 4 from sand flies. For genetic characterization of these stocks, multilocus enzyme electrophoresis (MLEE) and random amplified polymorphic DNA (RAPD) were used. Twenty six of the 35 stocks were identified as either Leishmania (V.) panamensis or L. (V.) guyanensis, 2 stocks were identified as L. (V.) braziliensis, the 2 stocks from sloths showed specific genotypes, and 5 stocks were characterized as hybrids between L. (V.) braziliensis and L. (V.) guyanensis. These data show that genetic diversity of Leishmania in Ecuador is high and that L. (V.) panamensis/guyanensis is the dominant group in this country. The genetic analysis questioned the distinctness between the two species L.(V.) panamensis and L. (V.) guyanensis, since MLEE and RAPD data did not indicate that L. (V.) panamensis and L. (V.) guyanensis correspond to distinct monophyletic lines. Population genetic analysis performed on the L. (V.) panamensis/guyanensis group favors the hypothesis of a basically clonal population structure. (+info)
Cutaneous leishmaniasis following local trauma: a clinical pearl.
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Cutaneous leishmaniasis is acquired from the bite of an infected sand fly and can result in chronic skin lesions that develop within weeks to months after a bite. Local trauma has been implicated as a precipitating event in the development of skin lesions in patients who have been infected with Leishmania species. Here we report a case series and review the literature on patients who developed cutaneous leishmaniasis after local trauma, which may familiarize clinicians with this presentation. (+info)
Interleukin (IL)-13 is the predominant Th2 cytokine in localized cutaneous leishmaniasis lesions and renders specific CD4+ T cells unresponsive to IL-12.
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Semiquantitative reverse transcription-polymerase chain reaction analysis of leishmania lesion cytokine profile showed a Th2 cytokine expression pattern, as reflected by interleukin (IL)-4 and IL-13 mRNA expression. There was a predominance of IL-13 in most lesions from patients with American localized cutaneous leishmaniasis caused by Leishmania guyanensis. IL-13 production by peripheral blood mononuclear cells in response to specific leishmania antigens was confirmed in these patients. The absence of the second chain of the IL-12 receptor (IL-12Rbeta2) mRNA expression in lesions and the presence of specific IgE and IgG4 in some serum samples demonstrated the functional role of these Th2 cytokines. IL-13, unlike IL-4, rendered specific T cells unresponsive to IL-12 by inhibiting the expression of the IL-12Rbeta2 chain. These data establish the crucial role of IL-13 in human cutaneous leishmaniasis. (+info)
Comparison of cutaneous leishmaniasis due to Leishmania (Viannia) braziliensis and L. (V.) guyanensis in Brazil: clinical findings and diagnostic approach.
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We compared the clinical findings and diagnostic methods for 66 patients with cutaneous leishmaniasis in the state of Bahia, Brazil, who were infected by Leishmania (Viannia) braziliensis (group A), with those for 68 patients in the state of Amazonas, Brazil, who were mainly infected by Leishmania (Viannia) guyanensis (group B). Differences were observed with regard to number, size, and location of skin lesions and to the pattern of lymphatic involvement. Patients in group B had smaller and more numerous lesions, which were frequently located above the waist, versus the larger but less numerous lesions among patients in group A, which were usually located on the lower limbs. Lymphatic involvement was present in 55 (83.3%) of the 66 patients in group A and in 42 (61.8%) of the 68 patients in group B (P=0.005). The positivity rates of imprints and skin culture procedures were higher in group B. Sensitivity of in vitro culture of skin aspirates was 47.0% and 91.2% for groups A and B, respectively (P<.001). Although hamster inoculation showed similar results in both groups, the interval before development of disease was shorter in group B. Our data provide substantial evidence that indicate that the disease caused by these species differs with regard to clinical presentation and diagnostic approach. (+info)
Cultivation and characterization of stable Leishmania guyanensis complex axenic amastigotes derived from infected U937 cells.
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The study of the differential regulation of several genes, in both Leishmania parasite life cycle forms, has been simplified by the development of in vitro axenic amastigote culture. Different reports have described extracellular amastigote production and maintenance from several Leishmania spp. A general approach to induce amastigote-like transformation includes progressive pH and temperature changes. Production of axenic amastigotes in continuous cultures using amastigotes recovered from macrophages is described in this report. Leishmania (Viannia) panamensis (M/HOM/PA/71/LS94) and Leishmania (V). guyanensis (M/HOM/BR/75/M4147) intracellular amastigotes were recovered from the human macrophage-like U937 cell line previously infected with promastigotes. The parasites were immediately adapted for growth and kept as axenic amastigotes at 34 degrees C and acidic pH. These organisms were able to infect macrophage cell lines, maintain amastigote morphologic features, and express stage-specific transcripts. The relevance of axenic amastigotes in characterizing virulence factors in American leishmaniasis is discussed. (+info)
Comparison of cutaneous leishmaniasis due to Leishmania (Viannia) braziliensis and L. (V.) guyanensis in Brazil: therapeutic response to meglumine antimoniate.
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We conducted a quasi-experimental study to compare the response to meglumine antimoniate in patients with localized cutaneous leishmaniasis from two endemic areas of Brazil that were infected by two Leishmania species. Sixty-one were infected by Leishmania (Viannia) braziliensis (group B) and 57 by L. (V.) guyanensis (group G). All had a parasitologically proven diagnosis and were treated with 20 mg of pentavalent antimonial (SbV)/kg/day given intravenously or intramuscularly for 20 days. Main outcomes were diagnosed using clinical criteria three months after treatment and patients were followed for six months. Intention-to-treat analysis showed a higher failure rate in group G (relative risk [RR] = 1.5, 95% confidence interval [CI] = 1.1-2.0, chi2 = 7.44, P = 0.006). The analysis using an explanatory approach including 52 patients from group B and 49 from group G, who were regularly treated and followed for six months, showed a low cure rate (50.8% in group B and 26.3% in group G) with a greater risk of failure in the latter group (RR = 1.7, 95% CI = 1.2-2.5, chi2 = 8.56, P = 0.003). The effect of the etiologic agent remained significant after adjusting for age, disease duration, and site and number of lesions that were identified as predictors of failure in a logistic regression model. We concluded that Leishmania species constitute an important factor in predicting the outcome of cutaneous leishmaniasis treated with a pentavalent antimonial. (+info)
High intralesional interleukin-10 messenger RNA expression in localized cutaneous leishmaniasis is associated with unresponsiveness to treatment.
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The intralesional expression of cytokines (interleukin [IL]-4, IL-13, IL-10, and interferon-gamma) was analyzed in 65 patients with localized cutaneous leishmaniasis due to Leishmania guyanensis before specific treatment with pentamidine isethionate. The local expression of IL-10 was significantly higher in patients who responded poorly to treatment than in patients whose lesions were regressing. When an IL-10 level >10 (ratio of the concentration of IL-10 [pg/microL] to that of beta-actin [pg/microL]) was used as an indicator of treatment failure, the sensitivity of this test was 78.6, and the specificity was 72.5. Thus, high intralesional expression of IL-10 might predict a poor response to conventional treatment. (+info)
LACK-specific CD4(+) T cells that induce gamma interferon production in patients with localized cutaneous leishmaniasis during an early stage of infection.
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The profile of cytokines induced by soluble leishmania antigen (SLA) and the Leishmania homologue of the mammalian receptor for activated C kinase (LACK), a candidate vaccine against leishmaniasis, and the cellular source of the cytokines produced in response to these antigens were analyzed in patients infected with Leishmania guyanensis. Gamma interferon (IFN-gamma) and interleukin-10 (IL-10) were produced in response to LACK. Although LACK-specific CD4(+) cells producing IFN-gamma were isolated only during the early phase of infection (less than 30 days following the onset of infection), cells producing IL-10 in response to LACK were detected in all patients. CD4(+) T cells producing IFN-gamma and IL-13 were produced in response to SLA in all patients. SLA- and LACK-specific T cells are effector memory cells, as they are CD45RA(-) CCR7(-) CD4(+) T cells. CD4(+) T cells producing IFN-gamma are CD62L(-), and CD4(+) T cells producing IL-10 are CD62L(+), indicating that these cells have different tissue-homing capacities. These findings show that SLA and LACK induce both type 1 (IFN-gamma) and type 2 (IL-10 or IL-13) cell responses. (+info)