Fatores relacionados à ocorrência de leishmaniose tegumentar no Vale do Ribeira

INTRODUÇÃO: este estudo teve como objetivo identificar fatores ambientais e sociais determinantes na incidência da leishmaniose tegumentar americana no Vale do Ribeira no período de 1998 a 2006. MÉTODOS: foram utilizados dados secundários de domínio público dos 23 municípios que integram a região. O intervalo de tempo foi dividido em três períodos, pelas características gráficas dos coeficientes de incidência, os quais foram submetidos à análise por regressão linear múltipla. RESULTADOS: para o período de 1998 a 2000, as variáveis correlacionadas com a LTA foram índice de desenvolvimento humano médio (p = 0,007), renda per capita (p =0,390) e grau de urbanização (p = 0,079). No período de 2001 a 2003 e 2004 a 2006 as variáveis correlacionadas com LTA foram: a existência de flebotomíneos (p = 0,000 e p = 0,001) e a população urbana média (p = 0,007 e p = 0,001). CONCLUSÕES: esses dados demonstram a tendência de pauperização e urbanização da doença.

Primeira descrição epidemiológica da leishmaniose visceral em Campo Grande, Estado de Mato Grosso do Sul

Foi realizado estudo epidemiológico sobre casos de leishmaniose visceral notificados em Campo Grande de 2001 a 2006, utilizando-se dados do Sistema de Informação de Agravos de Notificação. Foram registradas 577 notificações com incidência de 1,47 casos/100.000hab em 2001, chegando a 20,98 casos /100.000hab em 2006, com notificações todos os meses a partir de 2002. Crianças até nove anos contribuíram com 40% dos casos. O sexo masculino contribuiu com 64% das notificações e o sexo feminino com 36%. A letalidade variou de 5% a 11%, com média de 8%. Dos 44 óbitos, 33 (75%) ocorreram no sexo masculino e 11 (25%) no sexo feminino. Embora os idosos tenham contribuído com 9% dos casos, a mortalidade entre eles alcançou 39%. Foram 27 casos de co-infecção Leishmania/HIV (5%) com letalidade de 15%, a maioria em homens dos 20 aos 49 anos. Constatou-se processo de endemização da doença com elevada incidência.

Leishmaniose tegumentar americana no Litoral Norte Paulista, período 1993 a 2005

A leishmaniose tegumentar americana adquiriu caráter epidêmico no Litoral Norte Paulista, desde a década de 1990. A partir de dados secundários, realizou-se estudo descritivo da doença no período de 1993 a 2005 nos quatro municípios que compõem a região e analisou-se a freqüência dos flebotomíneos capturados nos locais prováveis de transmissão. Foram notificados 689 casos autóctones de leishmaniose tegumentar, com casos isolados e agrupados, determinando uma distribuição espacial heterogênea, com sincronismo na manifestação e ciclicidade, em intervalo de seis a oito anos. Todas as faixas etárias foram acometidas, com ligeiro predomínio do sexo masculino, sem associação com uma ocupação. Capturou-se 2.758 flebotomíneos e a espécie Nyssomyia intermedia predominou (80,4%), no peri e intradomicílio. A doença apresentou perfil de transmissão peri e intradomiciliar, entre o periurbano e a mata, e no interior da mata. Neste caso, a transmissão estaria mais relacionada com os focos enzoóticos.

Lutzomyia longipalpis (Diptera, Psychodidae) em Cuesta Basáltica, na bacia hidrográfica do Rio Corumbataí, Região Centro-leste do Estado de São Paulo

A incidência das leishmanioses tegumentar e visceral americanas, em especial esta última (LVA), em hospedeiros caninos e humanos, encontra-se em crescente processo de expansão no Estado de São Paulo. Para a vigilância epidemiológica dessas endemias, torna-se fundamental o conhecimento da distribuição e da ecologia das diferentes espécies da fauna flebotomínea vetoras. Assim, a divulgação de novos encontros de seus vetores, sobretudo da Lutzomyia longipalpis, o principal vetor da LVA, é fundamental para apontar novas áreas de risco para a transmissão dessas doenças. Neste estudo, capturas de flebotomíneos foram realizadas em ambiente domiciliar, peridomiciliar e de mata, em diferentes localidades rurais dos municípios de Ipeúna e Itirapina, entre outubro de 2001 e fevereiro de 2004. Foram utilizadas armadilhas luminosas automáticas do tipo CDC, das 18h às 8h, em 14 noites, resultando 420 horas de exposição. Foram capturados 177 flebotomíneos pertencentes a doze espécies. A espécie mais abundante, Nyssomyia neivai, apontada como a principal vetora de LTA no Estado, contribuiu com 85,4% dos espécimes capturados em Ipeúna. O encontro de Lutzomyia longipalpis em uma caverna em Itirapina, aponta para o risco de estabelecimento da LVA na área e a necessidade de mais estudos locais sobre sua ecologia, sobretudo em relação à ocupação de ambientes antrópicos.

The finding of Lutzomyia almerioi and Lutzomyia longipalpis naturally infected by Leishmania spp. in a cutaneous and canine visceral leishmaniases focus in Serra da Bodoquena, Brazil

To identify natural infections by Leishmania spp. in insect vectors of cutaneous and visceral leishmaniasis, we performed field studies in natural and anthropic environments in the Guaicurus Settlement (Bodoquena Range) of the Bonito municipality, Mato Grosso do Sul state, Brazil. From October 2002 to October 2003, a total of 1395 sandfly females were captured with Shannon and light traps and dissected in search of flagellates. The sample is composed of a total of 13 species, with Lutzomyia almerioi (59.9%) and Lutzomyia longipalpis (31.4%) predominant. Infections by flagellates were directly observed in three of the dissected of Lu. almerioi females (0.36%). To increase the sensitivity of detection, DNA extracted from pools of the 1220 dissected females (Lu. almerioi 808, Lu. longipalpis 399 and Nyssomyia whitmani 13) was subjected to small subunit rRNA-based polymerase chain reactions (SSU-PCR). DNA from Leishmania (L.) infantum chagasi was detected in at least 0.37% of Lu. almerioi females and in 0.25% of Lu. longipalpis females. The DNA of the Leishmania (Viannia) sp. was detected in 0.12% of Lu. almerioi and in 0.70% of Lu. longipalpis. Leishmania (L.) amazonensis was found in 1.25% of Lu. longipalpis. Mixed infections of L. (Leishmania) sp. and L. (Viannia) sp. were found in 0.50% of Lu. longipalpis. When considering that each positive pool contained at least a single infected specimen, we found a 1.23% rate of Leishmania spp. infection among the total population of dissected female sand flies as determined by PCR. This is the first report of natural infection by L. (L.) infantum chagasi and L. (Viannia) sp. in Lu. almerioi. It is also the first report of infection by L. (Viannia) sp. in Lu. longipalpis. The observation that Lu. longipalpis and Lu. almerioi are naturally infected by agents of both cutaneous and visceral leishmaniases suggests that these two species play a role in the transmission (continua) (continuação) of these diseases within the study area. Furthermore, the finding that Lu. longipalpis has been naturally infected by L. (L.) amazonensis and L. (Viannia) sp., and Lu. almerioi by L. (L.) infantum chagasi and L. (Viannia), suggests their participation as permissive vectors

Adaptive Immunity against Leishmania Nucleoside Hydrolase Maps Its C-Terminal Domain as the Target of the CD4+ T Cell-Driven Protective Response

Nucleoside hydrolases (NHs) show homology among parasite protozoa, fungi and bacteria. They are vital protagonists in the establishment of early infection and, therefore, are excellent candidates for the pathogen recognition by adaptive immune responses. Immune protection against NHs would prevent disease at the early infection of several pathogens. We have identified the domain of the NH of L. donovani (NH36) responsible for its immunogenicity and protective efficacy against murine visceral leishmaniasis (VL). Using recombinant generated peptides covering the whole NH36 sequence and saponin we demonstrate that protection against L. chagasi is related to its C-terminal domain (amino-acids 199-314) and is mediated mainly by a CD4+ T cell driven response with a lower contribution of CD8+ T cells. Immunization with this peptide exceeds in 36.73 +/- 12.33% the protective response induced by the cognate NH36 protein. Increases in IgM, IgG2a, IgG1 and IgG2b antibodies, CD4+ T cell proportions, IFN-gamma secretion, ratios of IFN-gamma/IL-10 producing CD4+ and CD8+ T cells and percents of antibody binding inhibition by synthetic predicted epitopes were detected in F3 vaccinated mice. The increases in DTH and in ratios of TNF alpha/IL-10 CD4+ producing cells were however the strong correlates of protection which was confirmed by in vivo depletion with monoclonal antibodies, algorithm predicted CD4 and CD8 epitopes and a pronounced decrease in parasite load (90.5-88.23%; p = 0.011) that was long-lasting. No decrease in parasite load was detected after vaccination with the N-domain of NH36, in spite of the induction of IFN-gamma/IL-10 expression by CD4+ T cells after challenge. Both peptides reduced the size of footpad lesions, but only the C-domain reduced the parasite load of mice challenged with L. amazonensis. The identification of the target of the immune response to NH36 represents a basis for the rationale development of a bivalent vaccine against leishmaniasis and for multivalent vaccines against NHs-dependent pathogens.

A Novel Organotellurium Compound (RT-01) as a New Antileishmanial Agent

Leishmaniasis is a neglected disease and endemic in developing countries. A lack of adequate and definitive chemotherapeutic agents to fight against this infection has led to the investigation of numerous compounds. The aim of this study was to investigate the effect of RT-01, an organotellurane compound presenting biological activities, in 2 experimental systems against Leishmania amazonensis. The in vitro system consisted of promastigotes and amastigotes forms of the parasite, and the in vivo system consisted of L. amazonensis infected BALB/c mice, an extremely susceptible mouse strain. The compound proved to be toxic against promastigotes and amastigotes. The study also showed that treatment with RT-01 produces an effect similar to that treatment with the reference antimonial drug, Glucantime, in L. amazonensis infected mice. The best results were obtained following RT-01 intralesional administration (720 mu g/kg/day); mice showed significant delay in the development of cutaneous lesions and decreased numbers of parasites obtained from the lesions. Significant differences in tissue pathology consisted mainly of no expressive accumulation of inflammatory cells and well-preserved structures in the skin tissue of RT-01-treated mice compared with expressive infiltration of infected cells replacing the skin tissue in lesions of untreated mice. These findings highlight the fact that the apparent potency of organotellurane compounds, together with their relatively simple structure, may represent a new avenue for the development of novel drugs to combat parasitic diseases.

Antileishmanial Activity of the Hydroalcoholic Extract of Miconia langsdorffii, Isolated Compounds, and Semi-Synthetic Derivatives

The in vitro activity of the crude hydroalcoholic extract of the aerial parts of Miconia langsdorffii Cogn. was evaluated against the promastigote forms of L. amazonensis, the causative agent of cutaneous leishmaniasis in humans. The bioassay-guided fractionation of this extract led to identification of the triterpenes ursolic acid and oleanolic acid as the major compounds in the fraction that displayed the highest activity. Several ursolic acid semi-synthetic derivatives were prepared, to find out whether more active compounds could be obtained. Among these ursolic acid-derived substances, the C-28 methyl ester derivative exhibited the best antileishmanial activity.

High levels of T lymphocyte activation in Leishmania-HIV-1 co-infected individuals despite low HIV viral load

Background: Concomitant infections may influence HIV progression by causing chronic activation leading to decline in T-cell function. In the Americas, visceral (AVL) and tegumentary leishmaniasis (ATL) have emerged as important opportunistic infections in HIV-AIDS patients and both of those diseases have been implicated as potentially important co-factors in disease progression. We investigated whether leishmaniasis increases lymphocyte activation in HIV-1 co-infected patients. This might contribute to impaired cellular immune function. Methods: To address this issue we analyzed CD4(+) T absolute counts and the proportion of CD8(+) T cells expressing CD38 in Leishmania/HIV co-infected patients that recovered after anti-leishmanial therapy. Results: We found that, despite clinical remission of leishmaniasis, AVL co-infected patients presented a more severe immunossupression as suggested by CD4(+) T cell counts under 200 cells/mm(3), differing from ATL/HIV-AIDS cases that tends to show higher lymphocytes levels (over 350 cells/mm(3)). Furthermore, five out of nine, AVL/HIV-AIDS presented low CD4(+) T cell counts in spite of low or undetectable viral load. Expression of CD38 on CD8(+) T lymphocytes was significantly higher in AVL or ATL/HIV-AIDS cases compared to HIV/AIDS patients without leishmaniasis or healthy subjects. Conclusions: Leishmania infection can increase the degree of immune system activation in individuals concomitantly infected with HIV. In addition, AVL/HIV-AIDS patients can present low CD4(+) T cell counts and higher proportion of activated T lymphocytes even when HIV viral load is suppressed under HAART. This fact can cause a misinterpretation of these laboratorial markers in co-infected patients.

BALB/c Mice Infected with Antimony Treatment Refractory Isolate of Leishmania braziliensis Present Severe Lesions due to IL-4 Production

Background: Leishmania braziliensis is the main causative agent of cutaneous leishmaniasis in Brazil. Protection against infection is related to development of Th1 responses, but the mechanisms that mediate susceptibility are still poorly understood. Murine models have been the most important tools in understanding the immunopathogenesis of L. major infection and have shown that Th2 responses favor parasite survival. In contrast, L. braziliensis-infected mice develop strong Th1 responses and easily resolve the infection, thus making the study of factors affecting susceptibility to this parasite difficult. Methodology/Principal Findings: Here, we describe an experimental model for the evaluation of the mechanisms mediating susceptibility to L. braziliensis infection. BALB/c mice were inoculated with stationary phase promastigotes of L. braziliensis, isolates LTCP393(R) and LTCP15171(S), which are resistant and susceptible to antimony and nitric oxide (NO), respectively. Mice inoculated with LTCP393(R) presented larger lesions that healed more slowly and contained higher parasite loads than lesions caused by LTCP15171(S). Inflammatory infiltrates in the lesions and production of IFN-gamma, TNF-alpha, IL-10 and TGF-beta were similar in mice inoculated with either isolate, indicating that these factors did not contribute to the different disease manifestations observed. In contrast, IL-4 production was strongly increased in LTCP393(R)-inoculated animals and also arginase I (Arg I) expression. Moreover, anti-IL-4 monoclonal antibody (mAb) treatment resulted in decreased lesion thickness and parasite burden in animals inoculated with LTCP393(R), but not in those inoculated with LTCP15171(S). Conclusion/Significance: We conclude that the ability of L. braziliensis isolates to induce Th2 responses affects the susceptibility to infection with these isolates and contributes to the increased virulence and severity of disease associated with them. Since these data reflect what happens in human infection, this model could be useful to study the pathogenesis of the L. braziliensis infection, as well as to design new strategies of therapeutic intervention.

Artificial Lighting as a Vector Attractant and Cause of Disease Diffusion

BACKGROUND: Traditionally, epidemiologists have considered electrification to be a positive factor. In fact, electrification and plumbing are typical initiatives that represent the integration of an isolated population into modern society, ensuring the control of pathogens and promoting public health. Nonetheless, electrification is always accompanied by night lighting that attracts insect vectors and changes people's behavior. Although this may lead to new modes of infection and increased transmission of insect-borne diseases, epidemiologists rarely consider the role of night lighting in their surveys. OBJECTIVE: We reviewed the epidemiological evidence concerning the role of lighting in the spread of vector-borne diseases to encourage other researchers to consider it in future studies. DISCUSSION: We present three infectious vector-borne diseases-Chagas, leishmaniasis, and malaria-and discuss evidence that suggests that the use of artificial lighting results in behavioral changes among human populations and changes in the prevalence of vector species and in the modes of transmission. CONCLUSION: Despite a surprising lack of studies, existing evidence supports our hypothesis that artificial lighting leads to a higher risk of infection from vector-borne diseases. We believe that this is related not only to the simple attraction of traditional vectors to light sources but also to changes in the behavior of both humans and insects that result in new modes of disease transmission. Considering the ongoing expansion of night lighting in developing countries, additional research on this subject is urgently needed.

Tamoxifen Is Effective in the Treatment of Leishmania amazonensis Infections in Mice

Background: Chemotherapy is still a critical issue in the management of leishmaniasis. Until recently, pentavalent antimonials, amphotericin B or pentamidine compounded the classical arsenal of treatment. All these drugs are toxic and have to be administered by the parenteral route. Tamoxifen has been used as an antiestrogen in the treatment and prevention of breast cancer for many years. Its safety and pharmacological profiles are well established in humans. We have shown that tamoxifen is active as an antileishmanial compound in vitro, and in this paper we analyzed the efficacy of tamoxifen for the treatment of mice infected with Leishmania amazonensis, an etiological agent of localized cutaneous leishmaniasis and the main cause of diffuse cutaneous leishmaniasis in South America. Methodology/Principal Findings: BALB/c mice were infected with L. amazonensis promastigotes. Five weeks post-infection, treatment with 15 daily intraperitoneal injections of 20 mg/kg tamoxifen was administered. Lesion and ulcer sizes were recorded and parasite burden quantified by limiting dilution. A significant decrease in lesion size and ulcer development was noted in mice treated with tamoxifen as compared to control untreated animals. Parasite burden in the inoculation site at the end of treatment was reduced from 10(8.5 +/- 0.7) in control untreated animals to 10(5.0 +/- 0.0) in tamoxifen-treated mice. Parasite load was also reduced in the draining lymph nodes. The reduction in parasite number was sustained: 6 weeks after the end of treatment, 10(15.5 +/- 0.5) parasites were quantified from untreated animals, as opposed to 10(5.1 +/- 0.1) parasites detected in treated mice. Conclusions/Significance: Treatment of BALB/c mice infected with L. amazonensis for 15 days with tamoxifen resulted in significant decrease in lesion size and parasite burden. BALB/c mice infected with L. amazonensis represents a model of extreme susceptibility, and the striking and sustained reduction in the number of parasites in treated animals supports the proposal of further testing of this drug in other models of leishmaniasis.

Leishmania-Specific Surface Antigens Show Sub-Genus Sequence Variation and Immune Recognition

Background: A family of hydrophilic acylated surface (HASP) proteins, containing extensive and variant amino acid repeats, is expressed at the plasma membrane in infective extracellular (metacyclic) and intracellular (amastigote) stages of Old World Leishmania species. While HASPs are antigenic in the host and can induce protective immune responses, the biological functions of these Leishmania-specific proteins remain unresolved. Previous genome analysis has suggested that parasites of the sub-genus Leishmania (Viannia) have lost HASP genes from their genomes. Methods/Principal Findings: We have used molecular and cellular methods to analyse HASP expression in New World Leishmania mexicana complex species and show that, unlike in L. major, these proteins are expressed predominantly following differentiation into amastigotes within macrophages. Further genome analysis has revealed that the L. (Viannia) species, L. (V.) braziliensis, does express HASP-like proteins of low amino acid similarity but with similar biochemical characteristics, from genes present on a region of chromosome 23 that is syntenic with the HASP/SHERP locus in Old World Leishmania species and the L. (L.) mexicana complex. A related gene is also present in Leptomonas seymouri and this may represent the ancestral copy of these Leishmania-genus specific sequences. The L. braziliensis HASP-like proteins (named the orthologous (o) HASPs) are predominantly expressed on the plasma membrane in amastigotes and are recognised by immune sera taken from 4 out of 6 leishmaniasis patients tested in an endemic region of Brazil. Analysis of the repetitive domains of the oHASPs has shown considerable genetic variation in parasite isolates taken from the same patients, suggesting that antigenic change may play a role in immune recognition of this protein family. Conclusions/Significance: These findings confirm that antigenic hydrophilic acylated proteins are expressed from genes in the same chromosomal region in species across the genus Leishmania. These proteins are surface-exposed on amastigotes (although L. (L.) major parasites also express HASPB on the metacyclic plasma membrane). The central repetitive domains of the HASPs are highly variant in their amino acid sequences, both within and between species, consistent with a role in immune recognition in the host.

TESA-blot for the diagnosis of Chagas disease in dogs from co-endemic regions for Trypanosoma cruzi, Trypanosoma evansi and Leishmania chagasi

We standardized serodiagnosis of dogs infected with Trypanosoma cruzi using TESA (trypomastigote excreted-secreted antigen)-blot developed for human Chagas disease. TESA-blot showed 100% sensitivity and specificity. In contrast, ELISA using TESA (TESA-ELISA) or epimastigotes (epi-ELISA) as antigen yielded 100% sensitivity but specificity of 94.1% and 49.4%, respectively. When used in field studies in an endemic region for Chagas disease, visceral leishmaniasis and Trypanosoma evansi (Mato Grosso do Sul state, Central Brazil), positivities were 9.3% for TESA-blot, 10.7% for TESA-ELISA and 32% for epi-ELISA. Dogs from a non-endemic region for these infections (Rondonia state, western Amazonia) where T cruzi is enzootic showed positivity of 4.5% for TESA-blot and epi-ELISA and 6.8% for TESA-ELISA. Sera from urban dogs from Santos, Sao Paulo, where these diseases are absent, yielded negative results. TESA-blot was the only method that distinguished dogs infected with T cruzi from those infected with Leishmania chagasi and/or Trypanosoma evansi. (C) 2009 Published by Elsevier B.V.

Splenectomy Increases Mortality in Murine Trypanosoma cruzi Infection

The spleen is a secondary lymphoid organ that harbours a variety of cells such as T and B lymphocytes and antigen-presenting cells important to immune response development. In this study, we evaluated the impact of spleen removal in the immune response to experimental Trypanosoma cruzi infection. C57BL/6 mice were infected with Y strain of the parasite and infection was followed daily. Mice that underwent splenectomy had fewer parasites in peripheral blood at the peak of infection; however, mortality was increased. Histological analysis of heart and liver tissues revealed an increased number of parasites and inflammatory infiltrates at these sites. Spleen removal was associated with reduction in IFN-gamma and TNF-alpha production during infection as well as with a decrease in specific antibody secretion. Haematological disorders were also detected. Splenectomized mice exhibited severe anaemia and decreased bone marrow cell numbers. Our results indicate that spleen integrity is critical in T. cruzi infection for the immune response against the parasite, as well as for the control of bone marrow haematological function.