CD4+ and CD8+ T-cell multi-epitope chimeric protein associated with an MPLA adjuvant induce protective efficacy and long-term immunological memory for the immunoprophylaxis of American Tegumentary Leishmaniasis.

American Tegumentary Leishmaniasis (ATL) is a disease of high severity and incidence in Brazil, in addition to being a worldwide concern in public health. Leishmania amazonensis is one of the etiological agents of ATL, and the inefficiency of control measures, associated with the high toxicity of the treatment and the lack of effective immunoprophylactic strategies, makes the development of vaccines indispensable and imminent. In this light, the present study proposes to elaborate a chimeric protein (rChiP), based on the fusion of multiple epitopes of CD4+/CD8+ T cells, identified in the immunoproteome of the parasites L. amazonensis and L. braziliensis. The designed chimeric protein was tested in the L. amazonensis murine model of infection using the following formulations: 25 µg of the rChiP in saline (rChiP group) and 25 µg of the rChiP plus 25 µg of MPLA-PHAD® (rChiP+MPLA group). After completing immunization, CD4+ and CD8+ T cells, stimulated with SLa-Antigen or rChiP, showed an increased production of nitric oxide and intracytoplasmic pro-inflammatory cytokines, in addition to the generation of central and effector memory T cells. rChiP and rChiP+MPLA formulations were able to promote an effective protection against L. amazonensis infection determined by a reduction in the development of skin lesions and lower parasitic burden. Reduction in the development of skin lesions and lower parasitic burden in the vaccinated groups were associated with an increase of nitrite, CD4+/CD8+IFN-γ+TNF-α+ and CD4+/CD8+CD44highCD62Lhigh/low T cells, IgGTotal, IgG2a, and lower rates of IgG1 and CD4+/CD8+IL-10+. This data suggests that proposed formulations could be considered potential tools to prevent ATL.

Evaluation of murine OX40L-murine IgG1(MM1) fusion protein on immunogenicity against L. mexicana infection in BALB/c mice.

The majority of OX40L is found on professional antigen-presenting cells (APC), the potency of OX40L to enhance the immunogenicity of potential vaccines against leishmania is not yet fully investigated. There is no report of administration of OX40L on cutaneous leishmaniasis either in therapy or prophylactic immunisation and the present study for the first time reports the effect of OX40L on L. mexicana infection. In this study, B9B8E2 cells were transfected with the murine OX40L and IgG1 plasmids, were used to produce the mOX40-mIgG1 (MM1). The therapeutic effects of MM1(mOX40L-mIgG1) was tested in a challenge experiment using L. mexicana infected BALB/c mice. Mice received two doses of MM1, on day 3 and 7 after the infection. Mice receiving MM1 generated an inflammatory reaction a few days after the injection of the OX40L, which was gradually dampened and finally disappeared 3 weeks later. There was a significant delay in the growth of developing lesions in mice receiving OX40L compared to controls injected with PBS and the size of lesions in the group receiving MM1 was significantly smaller than that of injected with either PBS. 40% of mice given MM1 remained lesion free for two months, when experiments were terminated. The results clearly indicate the high therapeutic effect of mOX40L-mIgG1 fusion protein in L. mexicana infection. The effect of OX40L on the enhancement of immunisation, needs to be further investigated for developing new vaccine strategies.

Análisis del comportamiento epidemiológico de Leishmaniasis cutánea en Perú 2016-2021 / Analysis of the epidemiological behavior of cutaneous leishmaniasis in Peru 2016-2021

La leishmaniasis cutánea (LC) es una patología cutánea inmunomediada causada principalmente por Leishmania (L.) major, Leishmania tropica, Leishmania braziliensis, L. mexicana y L. amazonensis. La carga de la LC en términos de morbilidad y estigmas sociales se concentra en ciertos países en desarrollo de Asia, África y Sudamérica. Las personas con LC asintomática representan una gran proporción de los individuos infectados en las zonas endémicas que no presentan ninguna lesión y pueden controlar la infección mediante mecanismos aún no del todo conocidos. En la actualidad, no existe ninguna medida profiláctica de control aprobada para la LC. Este reporte epidemiológico reveló que la LC prevalecía en las áreas geográficas de Selva y Sierra de Perú, mientras que departamentos como Ancash y La Libertad, áreas de la Costa, también estuvieron involucradas en el reporte de casos en los últimos años. El patrón de casos de LC reportados en los distintos departamentos del país tuvo un comportamiento muy parecido en el periodo comprendido entre 2016 y 2021, predominando en las primeras 4 o 5 semanas epidemiológicas la mayor frecuencia de pacientes enfermos con lesiones dérmicas compatibles y corroboradas con LC. La enfermedad es endémica en muchas partes del país, por eso se necesitan más esfuerzos y enfoques integrados para combatir esta patología(AU)

Cutaneous leishmaniasis (CL) is an immune-mediated skin pathology caused mainly by Leishmania (L.) major, Leishmania tropica, Leishmania braziliensis, L. mexicana and L. amazonensis. The burden of CL in terms of disease and social stigma is concentrated in certain developing countries in Asia, Africa, and South America. People with asymptomatic CL represent a large proportion of infected individuals in endemic areas who do not have any lesions and can control the infection through mechanisms that are not fully understood. Currently, there is no approved prophylactic control measure for CL. This epidemiological report revealed that CL was prevalent in the Selva and Sierra geographic areas of Peru, while departments such as Ancash and La Libertad, coastal areas, were also involved in the reporting of cases in recent years. The pattern of CL cases reported in the different departments of the country had a very similar behavior in the period between 2016 and 2021, with the highest frequency of sick patients with skin lesions compatible and corroborated with CL predominating in the first 4 or 5 epidemiological weeks. The disease is endemic in many parts of the country, so more efforts and integrated approaches are needed to combat this pathology(AU)

Identification of Immunodominant Antigens From a First-Generation Vaccine Against Cutaneous Leishmaniasis.

Leishmaniasis is a neglected tropical disease (NTD) caused by parasites belonging to the Leishmania genus for which there is no vaccine available for human use. Thus, the aims of this study are to evaluate the immunoprotective effect of a first-generation vaccine against L. amazonensis and to identify its immunodominant antigens. BALB/c mice were inoculated with phosphate buffer sodium (PBS), total L. amazonensis antigens (TLAs), or TLA with Poly (I:C) and Montanide ISA 763. The humoral and cellular immune response was evaluated before infection. IgG, IgG1, and IgG2a were measured on serum, and IFN-γ, IL-4, and IL-10 cytokines as well as cell proliferation were measured on a splenocyte culture from vaccinated mice. Immunized mice were challenged with 104 infective parasites of L. amazonensis on the footpad. After infection, the protection provided by the vaccine was analyzed by measuring lesion size, splenic index, and parasite load on the footpad and spleen. To identify immunodominant antigens, total proteins of L. amazonensis were separated on 2D electrophoresis gel and transferred to a membrane that was incubated with serum from immunoprotected mice. The antigens recognized by the serum were analyzed through a mass spectrometric assay (LC-MS/MS-IT-TOF) to identify their protein sequence, which was subjected to bioinformatic analysis. The first-generation vaccine induced higher levels of antibodies, cytokines, and cell proliferation than the controls after the second dose. Mice vaccinated with TLA + Poly (I:C) + Montanide ISA 763 showed less footpad swelling, a lower splenic index, and a lower parasite load than the control groups (PBS and TLA). Four immunodominant proteins were identified by mass spectrometry: cytosolic tryparedoxin peroxidase, an uncharacterized protein, a kinetoplast-associated protein-like protein, and a putative heat-shock protein DNAJ. The identified proteins showed high levels of conserved sequence among species belonging to the Leishmania genus and the Trypanosomatidae family. These proteins also proved to be phylogenetically divergent to human and canine proteins. TLA + Poly (I:C) + Montanide ISA 763 could be used as a first-generation vaccine against leishmaniasis. The four proteins identified from the whole-protein vaccine could be good antigen candidates to develop a new-generation vaccine against leishmaniasis.

Cutaneous leishmaniasis–Awareness, knowledge and practices among general population in rural and urban areas in Malakand region, Pakistan / Leishmaniose cutânea - conscientização, conhecimentos e práticas entre a população em geral nas áreas rurais e urbanas da região de Malakand, Paquistão

Malakand region is an endemic area for cutaneous leishmaniasis (CL). However, there are limited number of studies of this disease in Pakistan. Therefore, a study was conducted to understand the level of awareness attitude and practice among the residents of Makaland towards CL and the disease vectors. This study adopted a cross-sectional approach with a total of 400 respondents (n=93 rural and n= 307 urban). Overall, the population in Malakand region (61.2%) were well-informed in the role of sand fly in transmitting diseases, but most lack knowledge on the vector's behavior and almost a quarter (24.5%) were unable to provide knowledge on proper control measures. Alarmingly, the practice and attitudes of the general population was not satisfactory as close to half (49.8%) of the population did adopt any control method. This study calls for increase in awareness through health education campaign to reduce the risk of cutaneous leishmaniasis outbreaks in the future.(AU)

A região de Malakand é uma área endêmica para leishmaniose cutânea (CL). No entanto, há um número limitado de estudos sobre esta doença no Paquistão. Portanto, foi realizado um estudo para entender o nível de atitude e prática de conscientização entre os residentes de Makaland em relação aos CL e os vetores da doença. Este estudo adotou uma abordagem transversal com um total de 400 entrevistados (n = 93 rural e n = 307 urbano). No geral, a população da região de Malakand (61,2%) estava bem informada sobre o papel da mosca na transmissão de doenças, mas a maioria não possui conhecimento sobre o comportamento do vetor e quase um quarto (24,5%) foi incapaz de fornecer conhecimento sobre medidas de controle adequadas . De maneira alarmante, a prática e as atitudes da população em geral não foram satisfatórias, pois cerca da metade (49,8%) da população adotou algum método de controle. Este estudo apela ao aumento da conscientização por meio de campanhas de educação em saúde para reduzir o risco de surtos de leishmaniose cutânea no futuro.(AU)

Cutaneous leishmaniasis–Awareness, knowledge and practices among general population in rural and urban areas in Malakand region, Pakistan / Leishmaniose cutânea - conscientização, conhecimentos e práticas entre a população em geral nas áreas rurais e urbanas da região de Malakand, Paquistão

Malakand region is an endemic area for cutaneous leishmaniasis (CL). However, there are limited number of studies of this disease in Pakistan. Therefore, a study was conducted to understand the level of awareness attitude and practice among the residents of Makaland towards CL and the disease vectors. This study adopted a cross-sectional approach with a total of 400 respondents (n=93 rural and n= 307 urban). Overall, the population in Malakand region (61.2%) were well-informed in the role of sand fly in transmitting diseases, but most lack knowledge on the vector's behavior and almost a quarter (24.5%) were unable to provide knowledge on proper control measures. Alarmingly, the practice and attitudes of the general population was not satisfactory as close to half (49.8%) of the population did adopt any control method. This study calls for increase in awareness through health education campaign to reduce the risk of cutaneous leishmaniasis outbreaks in the future.

A região de Malakand é uma área endêmica para leishmaniose cutânea (CL). No entanto, há um número limitado de estudos sobre esta doença no Paquistão. Portanto, foi realizado um estudo para entender o nível de atitude e prática de conscientização entre os residentes de Makaland em relação aos CL e os vetores da doença. Este estudo adotou uma abordagem transversal com um total de 400 entrevistados (n = 93 rural e n = 307 urbano). No geral, a população da região de Malakand (61,2%) estava bem informada sobre o papel da mosca na transmissão de doenças, mas a maioria não possui conhecimento sobre o comportamento do vetor e quase um quarto (24,5%) foi incapaz de fornecer conhecimento sobre medidas de controle adequadas . De maneira alarmante, a prática e as atitudes da população em geral não foram satisfatórias, pois cerca da metade (49,8%) da população adotou algum método de controle. Este estudo apela ao aumento da conscientização por meio de campanhas de educação em saúde para reduzir o risco de surtos de leishmaniose cutânea no futuro.

Clinical, epidemiological and climatic factors related to the occurrence of cutaneous leishmaniasis in an endemic area in northeastern Brazil / Fatores clínicos, epidemiológicos e climáticos relacionados à ocorrência de leishmaniose cutânea em área endêmica no nordeste do Brasil

Cutaneous leishmaniasis (CL) is a neglected tropical disease with a wide distribution in the Americas. Brazil is an endemic country and present cases in all states. This study aimed to describe the occurrence, the underlying clinical and epidemiological factors, and the correlation of climatic variables with the frequency of reported CL cases in the municipality of Caxias, state of Maranhão, Brazil. This is a retrospective and descriptive epidemiological study based on data extracted from the Brazilian Information System of Diseases Notification, from 2007 to 2017. Maximum and minimum temperature, precipitation, and relative air humidity data were provided by the Brazilian National Institute of Meteorology. A total of 201 reported autochthonous CL cases were analyzed. The predominance of cases was observed in males (70.1%). The age range between 31 and 60 years old was the most affected, with 96 cases (47.9%). Of the total number of registered cases, 38.8% of the affected individuals were engaged in agriculture-related activities. The georeferenced distribution revealed the heterogeneity of disease occurrence, with cases concentrated in the Western and Southern regions of the municipality. An association was detected between relative air humidity (monthly mean) and the number of CL cases per month (p = 0.04). CL continues to be a concerning public health issue in Caxias. In this context, there is a pressing need to strengthen measures of prevention and control of the disease through the network of health services of the municipality, considering local and regional particularities.(AU)

A leishmaniose cutânea (CL) é uma doença tropical negligenciada, com ampla distribuição nas Américas. O Brasil é um país endêmico e apresenta casos em todos os estados. Este estudo teve como objetivo descrever a ocorrência, os fatores clínicos e epidemiológicos subjacentes e a correlação de variáveis climáticas com a frequência de casos de CL notificados no município de Caxias, estado do Maranhão, Brasil. Este é um estudo epidemiológico retrospectivo e descritivo, com base em dados extraídos da Notificação do Sistema Brasileiro de Informação de Doenças, de 2007 a 2017. Dados máximos e mínimos de temperatura, precipitação e umidade relativa do ar foram fornecidos pelo Instituto Nacional de Meteorologia. Foram analisados 201 casos de CL autóctones relatados. A predominância de casos foi observada no sexo masculino (70,1%). A faixa etária entre 31 e 60 anos foi a mais afetada, com 96 casos (47,9%). Do número total de casos registrados, 38,8% dos indivíduos afetados estavam envolvidos em atividades relacionadas à agricultura. A distribuição georreferenciada revelou a heterogeneidade da ocorrência da doença, com casos concentrados nas regiões oeste e sul do município. Foi detectada associação entre a umidade relativa do ar (média mensal) e o número de casos de CL por mês (p = 0,04). O CL continua sendo uma questão preocupante de saúde pública em Caxias. Nesse contexto, há uma necessidade premente de fortalecer medidas de prevenção e controle da doença por meio da rede de serviços de saúde do município, considerando as particularidades locais e regionais.(AU)

An appraisal of the scientific current situation and new perspectives in the treatment of cutaneous leishmaniasis.

Leishmaniasis is a Neglected Tropical Diseases caused by protozoan parasites of the genus Leishmania. It is a major health problem in many tropical and subtropical regions of the world and can produce three different clinical manifestations, among which cutaneous leishmaniasis has a higher incidence in the world than the other clinical forms. There are no recognized and reliable means of chemoprophylaxis or vaccination against infections with different forms of leishmaniasis. In addition, chemotherapy, unfortunately, remains, in many respects, unsatisfactory. Therefore, there is a continuing and urgent need for new therapies against leishmaniasis that are safe and effective in inducing a long-term cure. This review summarizes the latest advances in currently available treatments and improvements in the development of drug administration. In addition, an analysis of the in vivo assays was performed and the challenges facing promising strategies to treat CL are discussed. The treatment of leishmaniasis will most likely evolve into an approach that uses multiple therapies simultaneously to reduce the possibility of developing drug resistance. There is a continuous effort to discover new drugs to improve the treatment of leishmaniasis, but this is mainly at the level of individual researchers. Undoubtedly, more funding is needed in this area, as well as greater participation of the pharmaceutical industry to focus efforts on the development of chemotherapeutic agents and vaccines for this and other neglected tropical diseases.

Effect of Prophylactic Vaccination with the Membrane-Bound Acid Phosphatase Gene of Leishmania mexicana in the Murine Model of Localized Cutaneous Leishmaniasis.

Leishmaniasis is a disease caused by an intracellular protozoan parasite of the genus Leishmania. Current treatments for leishmaniasis are long, toxic, and expensive and are not available in some endemic regions. Attempts to develop an effective vaccine are feasible, but no vaccine is in active clinical use. In this study, the LmxMBA gene of Leishmania mexicana was selected as a possible vaccine candidate using the reverse vaccinology approach, and the prophylactic effect generated by DNA vaccination with this gene in a murine model of cutaneous leishmaniasis was evaluated. The results showed that prophylactic vaccination with pVAX1::LmxMBA significantly reduced the size of the lesion and the parasitic load on the footpad, compared to the control groups. At a histological level, a smaller number of parasites were evident in the dermis, as well as the absence of connective tissue damage. Mice immunized with plasmid pVAX1::LmxMBA induced immunity characterized by an increase in the IgG2a/IgG1 > 1 ratio and a higher rate of lymphocyte proliferation. In this study, immunization with the plasmid promoted an improvement in the macroscopic and microscopic clinical manifestations of the experimental infection by L. mexicana, with a T helper 1 response characterized by an IgG2a/IgG1 > 1 ratio and high lymphoproliferative response. These findings support immunization with the plasmid pVAX1::LmxMBA as a preventive strategy against cutaneous infection of L. mexicana.

Photodynamic inactivation of Leishmania braziliensis doubly sensitized with uroporphyrin and diamino-phthalocyanine activates effector functions of macrophages in vitro.

Photodynamic inactivation of Leishmania has been shown to render them non-viable, but retain their immunological activities. Installation of dual photodynamic mechanisms ensures complete inactivation of species in the Leishmania subgenus, raising the prospect of their safe and effective application as whole-cell vaccines against leishmaniasis. Here, we report the successful extension of this approach to L. braziliensis in the Viannia subgenus, viz. genetic engineering of promastigotes for cytosolic accumulation of UV-sensitive uroporphyrin (URO) and their loading with red light excitable phthalocyanines (PC) that was cationized by chemical engineering. The transgenic strategy used previously produced L. braziliensis transfectants, which gave the same phenotype of aminolevulinate (ALA)-inducible uroporphyria as found in Leishmania subgenus, indicative of pre-subgenus evolutionary origin for similar genetic deficiencies in porphyrin/heme biosynthesis. In the present study, 12 independent clones were obtained and were invariably ALA-responsive, albeit to different extent for uroporphyrinogenesis and UV-inactivation. In a separate study, L. braziliensis was also found, like other Leishmania spp., to take up diamino-PC (PC2) for red light inactivation. In vitro interactions of a highly uroporphyrinogenic clone with primary macrophages were examined with the intervention of URO/PC2-medated double-photodynamic inactivation to ascertain its complete loss of viability. Doubly sensitized L. braziliensis transfectants were photo-inactivated before (Strategy #1) or after (Strategy #2) loading of macrophages. In both cases, macrophages were found to take up L. braziliensis and degrade them rapidly in contrast to live Leishmania infection. The effector functions of macrophages became upregulated following their loading with L. braziliensis photodynamically inactivated by both strategies, including CD86 expression, and IL6 and NO production. This was in contrast to the immunosuppressive infection of macrophages with live parasites, marked by IL10 production. The results provide evidence that photodynamically inactivated L. braziliensis are susceptible to the degradative pathway of macrophages with upregulation of immunity relevant cytokine and co-stimulatory markers. The relative merits of the two loading strategies with reference to previous experimental vaccination were discussed in light of the present findings with L. braziliensis.

Leishmaniases of the New World from a historical and global perspective, from the 1930s to the 1960s.

The first autochthonous cases of cutaneous and mucocutaneous leishmaniasis in the Americas were described in 1909, but visceral leishmaniasis only erupted as a public health problem in the region in 1934. Today Brazil is the country with the most cases of American tegumentary leishmaniasis, and alongside India has the highest incidence of visceral leishmaniasis. Knowledge production and efforts to control these diseases have mobilized health professionals, government agencies and institutions, international agencies, and rural and urban populations. My research addresses the exchange and cooperation networks they established, and uncertainties and controversial aspects when notable changes were made in the approach to the New World leishmaniases.

Efficacy of factory-treated and dip-it-yourself long lasting insecticide-treated bednets against cutaneous leishmaniasis vectors in the sub-Andean region of Colombia: results after two years of use.

BACKGROUND: Long lasting insecticide-treated nets (LLINs) may be effective for vector control of cutaneous leishmaniasis (CL). Their efficacy, however, has not been sufficiently evaluated. OBJECTIVE: To evaluate the large-scale efficacy of LLINs on Lutzomyia longiflocosa entomological parameters up to two years post-intervention in the sub-Andean region of Colombia. METHODS: A matched-triplet cluster-randomised study of 21 rural settlements, matched by pre-intervention L. longiflocosa indoor density was used to compare three interventions: dip it yourself (DIY) lambda-cyhalothrin LLIN, deltamethrin LLIN, and untreated nets (control). Sand fly indoor density, feeding success, and parity were recorded using CDC light trap collections at 1, 6, 12, and 24 months post-intervention. FINDINGS: Both LLINs reduced significantly (74-76%) the indoor density and the proportion of fully engorged sand flies up to two years post-intervention without differences between them. Residual lethal effects of both LLINs and the use of all nets remained high throughout the two-year evaluation period. CONCLUSIONS: Both LLINs demonstrated high efficacy against L. longiflocosa indoors. Therefore, the deployment of these LLINs could have a significant impact on the reduction of CL transmission in the sub-Andean region. The DIY lambda-cyhalothrin kit may be used to convert untreated nets to LLINs increasing coverage.

Leishmaniases of the New World from a historical and global perspective, from the 1930s to the 1960s / Leishmanioses do Novo Mundo numa perspectiva histórica e global, dos anos 1930 aos 1960

Abstract The first autochthonous cases of cutaneous and mucocutaneous leishmaniasis in the Americas were described in 1909, but visceral leishmaniasis only erupted as a public health problem in the region in 1934. Today Brazil is the country with the most cases of American tegumentary leishmaniasis, and alongside India has the highest incidence of visceral leishmaniasis. Knowledge production and efforts to control these diseases have mobilized health professionals, government agencies and institutions, international agencies, and rural and urban populations. My research addresses the exchange and cooperation networks they established, and uncertainties and controversial aspects when notable changes were made in the approach to the New World leishmaniases.

Resumo Os primeiros casos de leishmaniose cutânea e mucocutânea autóctones das Américas foram descritos em 1909, e em 1934 a leishmaniose visceral irrompeu como problema de saúde pública na região. O Brasil tem hoje o maior número de casos da leishmaniose tegumentar americana e, junto com a Índia, a mais elevada incidência de leishmaniose visceral. A produção de conhecimentos e os esforços para controlar essas doenças mobilizaram, em nível global, profissionais de saúde, populações urbanas e rurais, instituições governamentais e agências internacionais. Recuperam-se aqui alguns desses agrupamentos, redes de troca e cooperação, incertezas e polêmicas, identificando-se mudanças na abordagem das leishmanioses do Novo Mundo.

Evaluation of different total Leishmania amazonensis antigens for the development of a first-generation vaccine formulated with a Toll-like receptor-3 agonist to prevent cutaneous leishmaniasis.

BACKGROUND Unfortunately, no any vaccine against leishmaniasis has been developed for human use. Therefore, a vaccine based on total Leishmania antigens could be a good and economic approach; and there are different methodologies to obtain these antigens. However, it is unknown whether the method to obtain the antigens affects the integrity and immune response caused by them. OBJECTIVES to compare the protein profile and immune response generated by total L. amazonensis antigens (TLA) produced by different methods, as well as to analyse the immune response and protection by a first-generation vaccine formulated with sonicated TLA (sTLA) and polyinosinic:polycytidylic acid [Poly (I:C)]. METHODS TLA were obtained by four different methodologies and their integrity and immune response were evaluated. Finally, sTLA was formulated with Poly (I:C) and their protective immune response was measured. FINDINGS sTLA presented a conserved protein profile and induced a strong immune response. In addition, Poly (I:C) improved the immune response generated by sTLA. Finally, sTLA + Poly (I:C) formulation provided partial protection against L. amazonensis infection. MAIN CONCLUSIONS The protein profile and immune response depend on the methodology used to obtain the antigens. Also, the formulation sTLA + Poly (I:C) provides partial protection against cutaneous leishmaniasis in mice.

Single-dose treatment for cutaneous leishmaniasis with an easily synthesized chalcone entrapped in polymeric microparticles.

Cutaneous leishmaniasis (CL) is a major health problem in many countries and its current treatment involves multiple parenteral injections with toxic drugs and requires intensive health services. Previously, the efficacy of a single subcutaneous injection with a slow-release formulation consisting of poly(lactide-co-glycolide) (PLGA) microparticles loaded with an antileishmanial 3-nitro-2-hydroxy-4,6-dimethoxychalcone (CH8) was demonstrated in mice model. In the search for more easily synthesized active chalcone derivatives, and improved microparticle loading, CH8 analogues were synthesized and tested for antileishmanial activity in vitro and in vivo. The 3-nitro-2',4',6'-trimethoxychalcone (NAT22) analogue was chosen for its higher selectivity against intracellular amastigotes (selectivity index = 1489, as compared with 317 for CH8) and more efficient synthesis (89% yield, as compared with 18% for CH8). NAT22 was loaded into PLGA / polyvinylpyrrolidone (PVP) polymeric blend microspheres (NAT22-PLGAk) with average diameter of 1.9 µm. Although NAT22-PLGAk showed similar activity to free NAT22 in killing intracellular parasites in vitro (IC50 ~ 0.2 µm), in vivo studies in Leishmania amazonensis - infected mice demonstrated the significant superior efficacy of NAT22-PLGAk to reduce the parasite load. A single intralesional injection with NAT22-PLGAk was more effective than eight injections with free NAT22. Together, these results show that NAT22-PLGAk is a promising alternative for single-dose localized treatment of CL.

Understanding the role of disease knowledge and risk perception in shaping preventive behavior for selected vector-borne diseases in Guyana.

BACKGROUND: Individual behavior, particularly choices about prevention, plays a key role in infection transmission of vector-borne diseases (VBDs). Since the actual risk of infection is often uncertain, individual behavior is influenced by the perceived risk. A low risk perception is likely to diminish the use of preventive measures (behavior). If risk perception is a good indicator of the actual risk, then it has important implications in a context of disease elimination. However, more research is needed to improve our understanding of the role of human behavior in disease transmission. The objective of this study is to explore whether preventive behavior is responsive to risk perception, taking into account the links with disease knowledge and controlling for individuals' socioeconomic and demographic characteristics. More specifically, the study focuses on malaria, dengue fever, Zika and cutaneous leishmaniasis (CL), using primary data collected in Guyana-a key country for the control and/or elimination of VBDs, given its geographic location. METHODS AND FINDINGS: The data were collected between August and December 2017 in four regions of the country. Questions on disease knowledge, risk perception and self-reported use of preventive measures were asked to each participant for the four diseases. A structural equation model was estimated. It focused on data collected from private households only in order to control for individuals' socioeconomic and demographic characteristics, which led to a sample size of 497 participants. The findings showed evidence of a bidirectional association between risk perception and behavior. A one-unit increase in risk perception translated into a 0.53 unit increase in self-reported preventive behavior for all diseases, while a one-unit increase in self-reported preventive behavior (i.e. the use of an additional measure) led to a 0.46 unit decrease in risk perception for all diseases (except CL). This study also showed that higher education significantly improves knowledge and that better knowledge increases the take up of preventive measures for malaria and dengue, without affecting risk perception. CONCLUSIONS: In trying to reach elimination, it appears crucial to promote awareness of the risks and facilitate access to preventive measures, so that lower risk perception does not translate into lower preventive behavior.

The potential of live attenuated vaccines against Cutaneous Leishmaniasis.

Cutaneous Leishmaniasis is a serious public health problem, typically affecting poor populations with limited access to health care. Control is largely dependent on chemotherapies that are inefficient, costly and challenging to deliver. Vaccination is an attractive and feasible alternative because long-term protection is typical in patients who recover from the disease. No human vaccine is yet approved for use, but several candidates are at various stages of testing. Live attenuated parasites, which stimulate long-term immune protection, have potential as effective vaccines, and their challenges relating to safety, formulation and delivery can be overcome. Here we review current data on the potential of live attenuated Leishmania vaccines and discuss possible routes to regulatory approval.

Vaccines for leishmaniasis and the implications of their development for American tegumentary leishmaniasis.

The leishmaniases are a collection of vector-borne parasitic diseases caused by a number of different Leishmania species that are distributed worldwide. Clinical and laboratory research have together revealed several important immune components that control Leishmania infection and indicate the potential of immunization to prevent leishmaniasis. In this review we introduce previous and ongoing experimental research efforts to develop vaccines against Leishmania species. First, second and third generation vaccine strategies that have been proposed to counter cutaneous and visceral leishmaniasis (CL and VL, respectively) are summarized. One of the major bottlenecks in development is the transition from results in animal model studies to humans, and we highlight that although American tegumentary leishmaniasis (ATL; New World CL) can progress to destructive and disfiguring mucosal lesions, most research has been conducted using mouse models and Old World Leishmania species. We conclude that assessment of vaccine candidates in ATL settings therefore appears merited.

Evaluation of different total Leishmania amazonensis antigens for the development of a first-generation vaccine formulated with a Toll-like receptor-3 agonist to prevent cutaneous leishmaniasis

BACKGROUND Unfortunately, no any vaccine against leishmaniasis has been developed for human use. Therefore, a vaccine based on total Leishmania antigens could be a good and economic approach; and there are different methodologies to obtain these antigens. However, it is unknown whether the method to obtain the antigens affects the integrity and immune response caused by them. OBJECTIVES to compare the protein profile and immune response generated by total L. amazonensis antigens (TLA) produced by different methods, as well as to analyse the immune response and protection by a first-generation vaccine formulated with sonicated TLA (sTLA) and polyinosinic:polycytidylic acid [Poly (I:C)]. METHODS TLA were obtained by four different methodologies and their integrity and immune response were evaluated. Finally, sTLA was formulated with Poly (I:C) and their protective immune response was measured. FINDINGS sTLA presented a conserved protein profile and induced a strong immune response. In addition, Poly (I:C) improved the immune response generated by sTLA. Finally, sTLA + Poly (I:C) formulation provided partial protection against L. amazonensis infection. MAIN CONCLUSIONS The protein profile and immune response depend on the methodology used to obtain the antigens. Also, the formulation sTLA + Poly (I:C) provides partial protection against cutaneous leishmaniasis in mice.

Efficacy of factory-treated and dip-it-yourself long lasting insecticide-treated bednets against cutaneous leishmaniasis vectors in the sub-Andean region of Colombia: results after two years of use

BACKGROUND Long lasting insecticide-treated nets (LLINs) may be effective for vector control of cutaneous leishmaniasis (CL). Their efficacy, however, has not been sufficiently evaluated. OBJECTIVE To evaluate the large-scale efficacy of LLINs on Lutzomyia longiflocosa entomological parameters up to two years post-intervention in the sub-Andean region of Colombia. METHODS A matched-triplet cluster-randomised study of 21 rural settlements, matched by pre-intervention L. longiflocosa indoor density was used to compare three interventions: dip it yourself (DIY) lambda-cyhalothrin LLIN, deltamethrin LLIN, and untreated nets (control). Sand fly indoor density, feeding success, and parity were recorded using CDC light trap collections at 1, 6, 12, and 24 months post-intervention. FINDINGS Both LLINs reduced significantly (74-76%) the indoor density and the proportion of fully engorged sand flies up to two years post-intervention without differences between them. Residual lethal effects of both LLINs and the use of all nets remained high throughout the two-year evaluation period. CONCLUSIONS Both LLINs demonstrated high efficacy against L. longiflocosa indoors. Therefore, the deployment of these LLINs could have a significant impact on the reduction of CL transmission in the sub-Andean region. The DIY lambda-cyhalothrin kit may be used to convert untreated nets to LLINs increasing coverage.