[Evaluation of the sensitization power of Montenegro skin test]

FLI1 gene influences lesion size and skin test may predict therapeutic response in cutaneous leishmaniasis

Genes associated with wound healing have been shown to be risk factors for cutaneous leishmaniasis (CL) which is caused by Leishmania braziliensis. In this study, we examined whether the genes previously associated with CL influenced the clinical outcome. Patients were genotyped and retrospectively classified as responders, who were cured with a single course of pentavalent antimony (Sbv), or as refractories, who did not respond to Sbv. Patients characterised as responders showed a stronger response to the leishmanin skin test (LST) when compared to the refractory subjects (p = 0.0003). Furthermore, we observed an association between the FLI1 CC genotype and an increased size of ulcers (p = 0.0170). We suggest that the leishmanin skin test may be a predictive tool for therapeutic outcome and reinforce FLI1 as a potential influencer of susceptibility and lesion size in CL.

CD45RO+ T Cells and T Cell Activation in the Long-Lasting Immunity after Leishmania infantum Infection

Manifestations of Leishmania infantum infection range from asymptomatic to symptomatic visceral leishmaniasis (VL). People with symptomatic VL (sVL) have suppressed immune responses against Leishmania antigens that are reversed after clinical cure. The intradermal leishmanin skin test (LST) is negative during sVL, but it becomes positive after treatment. The aim of this study was to compare T cell responses in individuals with sVL, recovered VL (RecVL), and endemic controls. Endemic controls were household contacts of a VL case and they were grouped by their LST results, either positive (LST+) or negative (LST-). Mononuclear cells were studied ex vivo or after stimulation with soluble Leishmania antigens (SLA); cell surface markers and cytokines were determined. T cells, ex vivo, from individuals with sVL and from LST+ individuals presented a higher activation for CD4⁺ and CD8⁺ cells expressing CD69. However, lymphocytes from sVL stimulated with SLA had lower percentages of CD4⁺ and CD8⁺ cells expressing CD69 and CD8⁺ cells expressing CD25, with no release of interferon-γ or tumor necrosis factor. sVL subjects had lower percentage of memory cells (CD4⁺ CD45RO+), ex vivo, without SLA stimulation than RecVL, LST+, or LST- (P = 0.0022). However, individuals with sVL had fewer regulatory cells after SLA stimulation (CD4⁺ CD25^HIGH, P = 0.04 and CD4⁺ FOXP3+, P = 0.02) than RecVL. The decrease in specific memory and activated CD4⁺ and CD8⁺ cells, as in response to Leishmania antigens, could explain, in part, the immune impairment during sVL. Finally, protective T cell responses are long lasting because both RecVL or LST+ individuals maintain a specific protective response to Leishmania years after the primary infection.

Evaluation of the reference value for the Montenegro skin test

INTRODUCTION

The Montenegro skin test (MST) has good clinical applicability and low cost for the diagnosis of American tegumentary leishmaniasis (ATL). However, no studies have validated the reference value (5mm) typically used to discriminate positive and negative results. We investigated MST results and evaluated its performance using different cut-off points.

METHODS

The results of laboratory tests for 4,256 patients with suspected ATL were analyzed, and 1,182 individuals were found to fulfill the established criteria. Two groups were formed. The positive cutaneous leishmaniasis (PCL) group included patients with skin lesions and positive direct search for parasites (DS) results. The negative cutaneous leishmaniasis (NCL) group included patients with skin lesions with evolution up to 2 months, negative DS results, and negative indirect immunofluorescence assay results who were residents of urban areas that were reported to be probable sites of infection at domiciles and peridomiciles.

RESULTS

The PCL and NCL groups included 769 and 413 individuals, respectively. The mean ± standard deviation MST in the PCL group was 12.62 ± 5.91mm [95% confidence interval (CI): 12.20-13.04], and that in the NCL group was 1.43 ± 2.17mm (95% CI: 1.23-1.63). Receiver-operating characteristic curve analysis indicated 97.4% sensitivity and 93.9% specificity for a cut-off of 5mm and 95.8% sensitivity and 97.1% specificity for a cut-off of 6mm.

CONCLUSIONS

Either 5mm or 6mm could be used as the cut-off value for diagnosing ATL, as both values had high sensitivity and specificity.

Effectiveness of insecticide spraying and culling of dogs on the incidence of Leishmania infantum infection in humans: a cluster randomized trial in Teresina, Brazil

Background

To evaluate the effect of insecticide spraying for vector control and elimination of infected dogs on the incidence of human infection with L. infantum, a randomized community intervention trial was carried out in the city of Teresina, Brazil.

Methods/Principal Findings

Within each of ten localities in the city, four blocks were selected and randomized to 4 interventions: 1) spraying houses and animal pens with insecticide; 2) eliminating infected dogs; 3) combination of spraying and eliminating dogs, and 4) nothing. The main outcome is the incidence of infection assessed by the conversion of the Montenegro skin test (MST) after 18 months of follow-up in residents aged ≥1 year with no previous history of visceral leishmaniasis (VL). Reactions were measured at 48–72 h, induration of ≥5 mm considered positive. Interventions were executed after the baseline interview and repeated 6 and 12 months later. The effects of each type of intervention scheme on the incidence of infection were assessed by calculating relative risks and 95% confidence intervals using Poisson population-averaged regression models with robust variance. Among the 1105 participants, 408 (37%) were MST positive at baseline. Of the 697 negatives, only 423 (61%) were reexamined at the end of the follow-up; 151 (36%) of them converted to a positive MST. Only dog culling had some statistically significant effect on reducing the incidence of infection, with estimates of effectiveness varying between 27% and 52%, depending on the type of analysis performed.

Conclusions/Significance

In light of the continuous spread of VL in Brazil despite the large scale deployment of insecticide spraying and dog culling, the relatively low to moderate effectiveness of dog culling and the non-significant effect of insecticide spraying on the incidence of human infection, we conclude that there is an urgent need for revision of the Brazilian VL control program.

Zoonotic visceral leishmaniasis (VL) constitutes a serious public health problem in the Americas, particularly in Brazil. The disease is caused by the protozoan parasite Leishmania infantum, which is transmitted by the bite of female sand flies, and dogs are the main source of infection. To decrease the risk of transmission, the Brazilian VL control program recommends residual insecticide spraying and environmental management for vector control, and culling of seropositive dogs in areas with moderate to high levels of transmission. Because there is a lack of scientific evidence supporting such interventions, we designed a study to assess the effectiveness of dog culling and residual insecticide spraying in the reduction of incidence of human VL infection. The results show that only dog culling had some statistically significant effect on reducing the incidence of infection, with estimates of effectiveness varying between 27% and 52%. In light of the continuous spread of VL in Brazil despite the large scale deployment of insecticide spraying and dog culling, the relatively low to moderate effectiveness of dog culling and the non-significant effect of insecticide spraying on the incidence of human infection, we conclude that there is an urgent need for revision of the Brazilian VL control program.

CD4(+) T cells defined by their Vβ T cell receptor expression are associated with immunoregulatory profiles and lesion size in human leishmaniasis

Leishmaniasis is caused by infection with the protozoan parasite, Leishmania, that parasitizes human cells, and the cellular immune response is essential for controlling infection. In order to measure the host T cell response to Leishmania infection, we have measured the expansion, activation state and functional potential of specific T cells as identified by their T cell receptor Vβ region expression. In a group of cutaneous leishmaniasis (CL) patients, we evaluated these characteristics in nine different T cell subpopulations as identified by their Vβ region expression, before and after specific Leishmania antigen stimulation. Our results show: (1) an increase in CD4(+) T cells expressing Vβ 5·2 and Vβ 24 in CL compared to controls; (2) a Leishmania antigen-induced increase in CD4(+) T cells expressing Vβ 5·2, 11, 12 and 17; (3) a profile of previous activation of CD4(+) Vβ 5·2-, 11- and 24-positive T cells, with higher expression of CD45RO, HLA-DR, interferon-γ, tumour necrosis factor-α and interleukin-10 compared to other Vβ-expressing subpopulations; (4) a positive correlation between higher frequencies of CD4(+) Vβ5·2(+) T cells and larger lesions; and (5) biased homing of CD4(+) T cells expressing Vβ 5·2 to the lesion site. Given that CL disease involves a level of pathology (ulcerated lesions) and is often followed by long-lived protection and cure, the identification of specific subpopulations active in this form of disease could allow for the discovery of immunodominant Leishmania antigens important for triggering efficient host responses against the parasite, or identify cell populations most involved in pathology.

Leishmaniose tegumentar americana: estudo clínico, epidemiológico e laboratorial realizado no Hospital Universitário de Campo Grande, Mato Grosso do Sul, Brasil

FUNDAMENTOS: Leishmaniose Tegumentar Americana é zoonose de manifestações clínicas variadas, em expansão no Brasil, sendo o estado de Mato Grosso do Sul importante área endêmica. OBJETIVOS: Avaliar clínica, epidemiológica e laboratorialmente pacientes com Leishmaniose Tegumentar Americana , atendidos no Hospital Universitário Maria Aparecida Pedrossian, Universidade Federal de Mato Grosso do Sul, Brasil (HU/UFMS). MÉTODOS: Trata-se de um estudo observacional do tipo transversal com abordagem descritiva e analítica. Foram avaliados, retrospectivamente, dados de pacientes suspeitos de Leishmaniose Tegumentar Americana , atendidos no HU/UFMS de 1998 a 2008, e encaminhados ao Laboratório de Parasitologia/UFMS para complementação diagnóstica. Para a inclusão neste estudo foram considerados critérios clínicos e laboratoriais. RESULTADOS: Quarenta e sete pacientes foram incluídos no estudo. Houve predominância de homens de 45 a 59 anos, com a forma cutânea, lesão única, ulcerada, em áreas expostas do corpo e com duração menor que seis meses. O comprometimento de mucosas foi crescente com o aumento da idade e maior em pacientes que procuraram atendimento tardiamente. Intradermorreação de Montenegro foi o exame de maior sensibilidade e o encontro do parasito mostrou-se mais difícil em lesões antigas. CONCLUSÃO: Suspeição diagnóstica precoce é de extrema importância para diagnóstico preciso. Associação de exame parasitológico e imunológico torna mais seguro o diagnóstico laboratorial.

Is an increased body mass index associated with a risk of cutaneous leishmaniasis?

All adults (n = 334) living in Brejo do Mutambal, an endemic area for cutaneous leishmaniasis, were included in this study. Contrary to our initial hypothesis, it was observed that men (23.7 ± 3.2 vs. 22.1 ± 2.6 kg/m²) and women (24.1 ± 4.7 vs. 22.5 ± 3.4 kg/m²) with cutaneous leishmaniasis presented higher body mass index than the controls.

Clinical epidemiological profile of American tegumentary leishmaniasis at the Pinto Sugar Mill in Moreno Municipality, Greater Metropolitan Recife, Pernambuco State, Brazil

American tegumentary leishmaniasis (ATL) is present in all regions of Pernambuco State, Brazil, where it is spreading, with the emergence of foci in new areas like the Municipality (County) of Moreno in Greater Metropolitan Recife. The objective of the current study was to assess the prevalence of infection and identify autochthonous cases of ATL. In April 2006 a population survey was performed using a questionnaire and the Montenegro skin test (MST) in 481 individuals from the Pinto Sugar Mill, of whom 47% were males and 74% were younger than 30 years. One hundred forty-four individuals (30%) showed a positive MST. Of these, five presented active lesions, 41 were cured after meglumine antimoniate treatment, and one showed a spontaneous cure. Indirect immunofluorescence (IIF) was performed on sera from 89 individuals and showed a 36% positive rate. The high ATL prevalence demonstrates the epidemiological spread of the disease in Greater Metropolitan Recife, a worrisome development since there are no effective measures for ATL control except ecological awareness raising to minimize the risk of infection.

Genetic predisposition to self-curing infection with the protozoan Leishmania chagasi: a genomewide scan

The protozoan Leishmania chagasi can cause disseminated, fatal visceral leishmaniasis (VL) or asymptomatic infection in humans. We hypothesized that host genetic factors contribute to this variable response to infection. A family study was performed in neighborhoods of endemicity for L. chagasi near Natal in northeastern Brazil. Study subjects were assessed for the presence of VL or asymptomatic infection, which was defined by a positive delayed-type hypersensitivity (DTH) skin test response to Leishmania antigen without disease symptoms. A genomewide panel of 385 autosomal microsatellite markers in 1254 subjects from 191 families was analyzed to identify regions of linkage. Regions with potential linkage to the DTH response on chromosomes 15 and 19, as well as a novel region on chromosome 9 with potential linkage to VL, were identified. Understanding the genetic factors that determine whether an individual will develop symptomatic or asymptomatic infection with L. chagasi may identify proteins essential for immune protection against this parasitic disease and reveal strategies for immunotherapy or prevention.

[Montenegro intradermoreaction after the test sequential repetitions in Porteirinha, Minas Gerais State, Brazil]

With the purpose of evaluating the response of sequential applications of Montenegro intradermoreaction (IDRM), we have repeated four times the test in the inhabitants of an endemic area for kala-azar, that resulted negative 3-4 years ago. Firstly, we have repeated three IDRM in those who remained negative, with a 60-day interval among them. In the second stage, we have performed a last reaction in all participants of the study. From the total of 49 individuals with prior negative IDRM, 19 (38.8%) have positivated the test in some of the times, 17 (34.7%) have given up the study and 13 (26.5%) remained with a negative result in all the applications. In the second stage, the repetition of IDRM has shown that from the 14 positive in some of the tests, 8 remained like this and 6 have become negative. Our results confirm the possibility of late hypersensitivity induction in some individuals as a consequence of IDRM application.