Lower galactosylation levels of the Lipophosphoglycan from Leishmania (Leishmania) major-like strains affect interaction with Phlebotomus papatasi and Lutzomyia longipalpis

BACKGROUND Leishmania major is an Old World species causing cutaneous leishmaniasis and is transmitted by Phlebotomus papatasi and Phlebotomus duboscqi. In Brazil, two isolates from patients who never left the country were characterised as L. major-like (BH49 and BH121). Using molecular techniques, these isolates were indistinguishable from the L. major reference strain (FV1). OBJECTIVES We evaluated the lipophosphoglycans (LPGs) of the strains and their behaviour in Old and New World sand fly vectors. METHODS LPGs were purified, and repeat units were qualitatively evaluated by immunoblotting. Experimental in vivo infection with L. major-like strains was performed in Lutzomyia longipalpis (New World, permissive vector) and Ph. papatasi (Old World, restrictive or specific vector). FINDINGS The LPGs of both strains were devoid of arabinosylated side chains, whereas the LPG of strain BH49 was more galactosylated than that of strain BH121. All strains with different levels of galactosylation in their LPGs were able to infect both vectors, exhibiting colonisation of the stomodeal valve and metacyclogenesis. The BH121 strain (less galactosylated) exhibited lower infection intensity compared to BH49 and FV1 in both vectors. MAIN CONCLUSIONS Intraspecific variation in the LPG of L. major-like strains occur, and the different galactosylation levels affected interactions with the invertebrate host.

Flebotomíneos (díptera, psychodidae) em focos urbanos de leishmaniose visceral no estado do Maranhão, Brasil / Sandflies (Diptera, Psychodidae) in urban outbreaks of visceral leishmaniasis in the state of Maranhão, Brazil

Foram objetos deste estudo a riqueza, a abundância relativa e a frequência mensal das espécies de flebotomíneos (Diptera, Psychodidae) em uma área urbana do município de Codó, estado doMaranhão, que registra elevada prevalência de leishmaniose visceral. Os insetos foram capturados com armadilhas luminosas do tipo CDC, das 18 h às 6 h, duas vezes por mês, de junho de 2012 a maio de 2013. Foram coletados 5.722 espécimes de 11 espécies, sendo 10 pertencentes ao gênero Lutzomyia e 1 ao gênero Brumptomyia. A abundância foi maior no peridomicílio (4.009 exemplares:66 por cento machos e 34 por cento fêmeas) do que no intradomicílio (1.713 exemplares: 55,9 por cento machos e 44,1 por cento fêmeas). A espécie mais abundante foi L. longipalpis (97,7 por cento) e juntamente com L. evandroi, L.sordelli e L. termitophila foram as mais constantes ao longo do ano. A frequência dos flebotomíneos mostrou-se maior no período seco (57,9 por cento), elevando-se com o aumento da temperatura média(p=0,0156; r=0,1007) e reduzindo-se com o aumento da umidade relativa do ar (p=0,0001;r=-0,1740). Sugerem-se ações de controle vetorial durante a estação seca quando os flebotomíneossão mais abundantes.

The richness, relative abundance and the monthly frequency of species of sandflies (Diptera,Psychodidae) in an urban area of the municipality of Codo, Maranhão, a state that records a highprevalence of visceral leishmaniasis, was studied. The insects were captured with CDC light traps,from 18 h to 6 h, twice per month from June 2012 to May 2013 and 5,722 specimens of 11 species, 10belonging to the genus Lutzomyia and one to the genus Brumptomyia were collected. The abundancewas higher outdoors (4,009 samples: 66 percent males and 34 percent females) than in households (1,713 samples:55.9 percent males and 44.1 percent females). The most abundant species was L. longipalpis (97.7 percent), whichtogether with L. evandroi, L.sordellii and L. termitophila were more constant throughout the year. Thefrequency of sandflies was higher in the dry season (57.9 percent), rising with increasing mean temperature(p=0.0156, r=0.1007) and showed a decrease with increasing relative humidity (p=0.0001, r=-0.1740).Vector control during the dry season, when sandflies are most abundant, is suggested.

The molecular detection of different Leishmania species within sand flies from a cutaneous and visceral leishmaniasis sympatric area in Southeastern Brazil

Over the last 20 years, there has been an increase in the number of leishmaniasis cases in Brazil. Belo Horizonte (BH) is one of the most highly populated Brazilian cities that is affected by visceral leishmaniasis (VL). The health services in BH are coordinated by a central nucleus that is subdivided into nine sanitary districts. Historically, the highest level of human VL cases was found in the northeast sanitary district (NSD). The objective of our study was to detect Leishmania infection in the phlebotomine sand flies collected in the NSD by dissection and molecular approaches. Following the occurrence of human VL cases in 2005, entomological captures were performed from July 2006-June 2007. Out of the 245 sand flies dissected, only three Lutzomyia longipalpis spp contained flagellates. The female sand flies were grouped into 120 pools according to date, collection site and species, with approximately 10 individual sand flies in each pool. Subsquently, the DNA was extracted and Leishmania spp and other parasites were detected and identified by polymerase chain reaction (PCR) and PCR-restriction fragment length polymorfism. Leishmania infantum was present in at least 19 percent of the Lu. longipalpis collected, in 3.8 percent of the Nyssomiya whitmani collected, in 33.3 percent of the Evandromiya termitophila collected and in 14.3 percent of the Nyssomiya intermedia collected. When the females of the cortelezzii complex were compared with each other, 3.2 percent of the females were infected with Leishmania braziliensis, whereas 3.2 percent of the females were infected with trypanosomatids.

Alternative PCR protocol using a single primer set for assessing DNA quality in several tissues from a large variety of mammalian species living in areas endemic for leishmaniasis

The aim of this work was to establish a modified pre-diagnostic polymerase chain reaction (PCR) protocol using a single primer set that enables successful amplification of a highly conserved mammalian sequence in order to determine overall sample DNA quality for multiple mammalian species that inhabit areas endemic for leishmaniasis. The gene encoding interphotoreceptor retinoid-binding protein (IRBP), but not other conserved genes, was efficiently amplified in DNA samples from tail skin, ear skin, bone marrow, liver and spleen from all of the species tested. In tissue samples that were PCR-positive for Leishmania, we found that DNA from 100 percent, 55 percent and 22 percent of the samples tested resulted in a positive PCR reaction for the IRBP, beta-actin and beta-globin genes, respectively. Nucleotide sequencing of an IRBP amplicon resolved any questions regarding the taxonomical classification of a rodent, which was previously based simply on the morphological features of the animal. Therefore, PCR amplification and analysis of the IRBP amplicon are suitable for pre-diagnostically assessing DNA quality and identifying mammalian species living in areas endemic to leishmaniasis and other diseases.

Experimental reinfection of BALB/c mice with different recombinant type I/III strains of Toxoplasma gondii: involvement of IFN-³ and IL-10

To assess reinfection of BALB/c mice with different Toxoplasma gondii strains, the animals were prime infected with the non-virulent D8 strain and challenged with virulent recombinant strains. Thirty days after challenge, brain cysts were obtained from surviving BALB/c mice and inoculated in Swiss mice to obtain tachyzoites for DNA extraction and PCR-RFLP analysis to distinguish the different T. gondii strains present in possible co-infections. Anti-Toxoplasma immune responses were evaluated in D8-primed BALB/c mice by detecting IFN-³ and IL-10 produced by T cells and measuring immunoglobulin levels in serum samples. PCR-RFLP demonstrated that BALB/c mice were reinfected with the EGS strain at 45 days post prime infection (dpi) and with the EGS and CH3 strains at 180 dpi. High levels of IFN-³ were detected after D8 infection, with no significant difference between 45 and 180-day intervals. However, higher IL-10 levels and higher plasmatic IgG1 and IgA were detected from samples obtained 180 days after infection. BALB/c mice were susceptible to reinfection with different recombinant T. gondii strains and this susceptibility correlated with enhancement of IL-10 production.

Leishmaniose tegumentar americana: apresentação pouco comum / American tegumentary leishmaniasis: an unusual presentation

Relata-se caso de leishmaniose tegumentar americana com lesões proeminentes na face. Os critérios diagnósticos incluíram dados clínicos e epidemiológicos, intradermorreação de Montenegro, identificação de Leishmania pela reação em cadeia da polimerase e resposta clínica ao tratamento. A importância do relato se deve ao fato de se tratar de caso incomum de leishmaniose tegumentar americana.

We report the case of a patient with American cutaneous leishmaniasis and prominent lesions on the face. Diagnostic criteria included clinical and epidemiological data, Montenegro's skin test, identification of Leishmania by means of polymerase chain reaction and clinical response to treatment. Our report is important to call attention to an unusual presentation of American cutaneous leishmaniasis.

The role of MHC haplotypes H2d/H2b in mouse resistance/susceptibility to cyst formation is influenced by the lineage of infective Toxoplasma gondii strain

Toxoplasma gondii strains displaying the Type I/III genotype are associated with acquired ocular toxoplasmosis in humans. Here, we used a mice model to characterize some immunological mechanisms involved in host resistance to infection with such strains. We have chosen the Type I/III strains D8, G2 and P-Br, which cause a chronic infection in mice that resembles human toxoplamosis. Mice deficient of molecules MyD88, IFN-gamma, and IL-12 were susceptible to all three parasite strains. This finding indicates the importance of innate mechanisms in controlling infection. On the other hand, MHC haplotype did not influenced resistance/susceptibility; since mice lineages displaying a same genetic background but different MHC haplotypes (H2b or H2d) developed similar mortality and cyst numbers after infection with those strains. In contrast, the C57BL/6 genetic background, and not MHC haplotype, was critical for development of intestinal inflammation caused by any of the studied strains. Finally, regarding effector mechanisms, weobserved that B and CD8+ T lymphocytes controlled survival,whereas the inducible nitric oxide synthase influenced cyst numbers in brains of mice infected with Type I/III strains. These findings are relevant to further understanding of the immunologic mechanisms involved in host protection and pathogenesis during infection with T. gondii.

Cepas de Toxoplasma gondii que apresentam o genótipo I/III são associadas a toxoplasmose ocular adquirida em humanos. No presente trabalho, nós utilizamos um modelo da doença em camundongos para caracterizar mecanismos imunológicos envolvidos na resistência do hospedeiro à infecção por aquelas cepas. Escolhemos as cepas D8, G2 e P-Br, que causam infecção crônica em camundongos, semelhante à toxoplasmose humana. Camundongos deficientes em MyD88, IFN-G e IL-12 foram susceptíveis a infecções com todas as três linhagens do parasita. Esses dados indicam a importância de mecanismos inatos no controle da infecção. Por outro lado, o haplótipo do MHC não influenciou na resistência/susceptibilidade, na medida em que linhagens de camundongos com um mesmo "background'' genético, mas diferentes haplótipos de MHC (H2b e H2d) apresentam o índice de mortalidade e número de cistos semelhantes após a infecção com aquelas cepas do parasita. Em contraste, o "background'' genético de C57BL/6, mas não o haplótipo de MHC, foi crítico para o desenvolvimento de inflamação intestinal causada pelas cepas estudadas. Finalmente, com relação aos mecanismos efetores, observamos que linfócitos B e T CD8+ controlam a sobrevivência após infecção. Por outro lado, a ativação da enzima óxido nítrico sintase induzida foi um fator importante para controle do número de cistos cerebrais em camundongos infectados com cepas do Tipo I/III. Esses achados são relevantes para o melhor entendimento dos mecanismos imunológicos envolvidos na proteção e patogênese durante infecção com T. gondii.

Diagnosing human asymptomatic visceral leishmaniasis in an urban area of the State of Minas Gerais, using serological and molecular biology techniques

A population-based cross-sectional study was set up in Sabará country, Southeastern Brazil, to identify asymptomatic human visceral leishmaniasis in an urban area of low disease prevalence. Blood was collected on filter paper (n=1,604 inhabitants) and examined by indirect immunofluorescent test, enzyme-linked immunosorbent assay and immunochromatographic strip test. The prevalence rates of infection ranged from 2.4 to 5.6 percent depending on the test used. One year later, venous blood was collected in a subset of 226 participants (102 seropositive and 124 seronegative). The tests performed were IFAT, ELISA, rk39-ELISA, polymerase chain reaction and hybridization with Leishmania donovani complex probe. No clinical signs or symptoms of leishmaniasis were observed. Using hybridization as a reference test, the sensitivity and specificity of serology were respectively: 24.8 and 71 percent (ELISA); 26.3 and 76.3 percent (rk-39); 30.1 and 63.4 percent (IFAT). Due to disagreements, different criteria were tested to define the infection and hybridization should be considered in epidemiological studies.

Um estudo seccional de base populacional foi desenvolvido no município de Sabará, região sudeste do Brasil, para identificar a leishmaniose visceral humana assintomática em uma área urbana de baixa prevalência da doença. Foi coletado sangue em papel filtro (n=1.604 moradores), sendo examinados pela reação de imunofluoresência indireta, ensaio imunoenzimático e teste imunocromatográfico (strip test). As taxas de prevalência da infecção variaram de 2,4 a 5,6 por cento, dependendo do teste utilizado. Um ano depois foi coletado sangue venoso de um subgrupo de 226 participantes (102 soropositivos e 124 soronegativos). Os testes realizados foram IFAT, ELISA, rk39-ELISA, reação em cadeia da polimerase e hibridização com sonda específica para o complexo Leishmania donovani. Não foi observado nenhum sinal clínico ou sintoma de leishmaniose. Usando a hibridização como teste de referência, a sensibilidade e especificidade dos testes sorológicos foram, respectivamente: 24.8 e 71 por cento (ELISA); 26,3 e 76,3 por cento (rk39-ELISA); 30,1 e 63,4 por cento (IFAT). Devido a discordâncias, diferentes critérios foram testados para definir a presença da infecção e a hibridização deveria ser considerada em estudos epidemiológicos.

Immunotherapy, immunochemotherapy and chemotherapy for American cutaneous leishmaniasis treatment

O tratamento de primeira escolha para leishmaniose tegumentar americana é o antimonial pentavalente. Embora este tratamento seja na maioria das vezes efetivo e indicado, devem ser consideradas as desvantagens tais como efeitos colaterais, longa duracão do tratamento e contra-indicacão para cardiopatas, nefropatas, idosos, grávidas e outras condicões. Com o advento da vacina antileishmaniose tegumentar americana para fins profiláticos e terapêuticos, associando-a ou não a outros fármacos, muitas pesquisas têm sido desenvolvidas, sendo a vacina a principal entre os atuais recursos no tratamento e prevencão da leishmaniose tegumentar americana. Em conclusão, a associacão do antimônio com a vacina (imunoquimioterapia) apresentou o mesmo índice de cura em relacão ao tratamento padrão (100%), e ainda reduziu o volume do sal em 17,9% e o tempo de cura significativamente, de 87 para 62 dias; conseqüentemente, reduzindo os efeitos colaterais.

Risk factors for Leishmania chagasi infection in an urban area of Minas Gerais State

Com o objetivo de identificar os determinantes da infeccão humana por Leishmania chagasi em uma área urbana, foi realizado um estudo seccional de base populacional utilizando-se métodos moleculares e sorológicos para identificar a infeccão. Os participantes foram entrevistados utilizando-se questionário pré-codificado. Dois critérios foram testados para identificar os fatores de risco: Modelo 1- incluindo todos os participantes positivos na hibridizacão com sonda para o complexo Leishmania donovani; Modelo 2- incluindo todos os participantes positivos na hibridizacão e em pelo menos um teste sorológico. No Modelo 1, as variáveis associadas à infeccão foram: criar pássaros, encontrar-se fora de casa entre 18:00-22:00h e não ter o lixo coletado. No Modelo 2, as variáveis associadas à infeccão foram: família conhecer o vetor, não ter o lixo coletado, lixo não removido ou queimado, criar pássaros, proximidade de áreas erodidas. Os fatores de risco identificados foram associados às condicões das moradias, presenca de animais e probabilidade de contato com flebotomíneos.

The use of radionuclide DNA probe technology for epidemiological studies of tegumentary leishmaniasis in Mato Grosso state

DNA hybridisation, using probes labelled with 32P, was used to type Leishmania samples isolated from patients living in endemic areas of Mato Grosso State (Brazil), and clinically diagnosed as having tegumentary leishmaniasis. kDNA cloned mini-circle probes specific for the Leishmania mexicana and Leishmania braziliensis complexes were used. The results showed that L. braziliensis is the predominant group infecting human patients in the state. Sixty-eight samples were typed, 64 samples (94.1 percent) belonging to the L. braziliensis complex and only four (5.9 percent) belonging to the L. mexicana complex. Accurate identification of the Leishmania permits better orientation of the medical follow-up, since clinical manifestations may vary depending on the complex to which the parasite belongs. The epidemiological information furnished by the identification of the Leishmania in given endemic area is also essential for the design of appropriate control measures

Hibridização, utilizando sondas de DNA marcadas com 32P, foi utilizada para a tipagem de amostras de Leishmania isoladas de pacientes do estado do Mato Grosso (Brasil), diagnosticados clinicamente como portadores de leishmaniose tegumentar. Sondas de minicírculos clonados de kDNA, específicas para os complexos Leishmania mexicana e Leishmania braziliensis, foram utilizadas. Os resultados demonstraram que o complexo L. brasiliensis é o grupo predominante infectando pacientes humanos no estado do Mato Grosso. Foram tipadas 68 amostras: 64 (94,1 por cento) foram identificadas como pertencentes ao complexo L. brasiliensis e somente 4 (5,9 por cento) como pertencentes ao complexo L. mexicana. A tipagem de Leishmania é importante para um melhor acompanhamento médico, uma vez que as manifestações clínicas podem variar em função do complexo ao qual o parasita pertence. A informação fornecida pela identificação também é essencial para a definição das medidas de controle mais adequadas e compreensão da epidemiologia da doença.

Leishmaniose visceral no Brasil: quadro atual, desfios e perspectivas / Visceral Leishmaniasis in Brazil: current status, challenges and prospects

No Brasil, a importância da leishamniose visceral reside não somente na sua alta incidência e ampla distribuição, mas também na possibilidade de assumir formas graves e letais quando associada ao quadro de má nutrição e infecções concomitantes. A crescente urbanização da doença ocorrida nos últimos 20 anos coloca em pauta a discussão das estratégias de controle empregadas. Neste artigo foram analisados os principais aspectos biológicos, ambientais e sociais que influenciaram no processo de expansão e urbanização dos focos da doença. Os métodos disponíveis para o diagnóstico e tratamento não apresentaram a eficácia e aplicabilidade desejadas, embora avanços promissores tenham sido alcançados com as pesquisas de novos testes diagnósticos e drogas terapêuticas. As medidas de controle da doença até agora implementadas foram incapazes de eliminar a transmissão e impedir a ocorrência de novas epidemias. É feita uma breve análise destas medidas e dos desafios a serem enfrentados. A prevenção da doença nos cães através da imunoprofilaxia aparece como uma alternativa para o controle. Uma nova vacina para cães, já testada em campo, está sendo industrializada e será comercializada no Brasil a partir de 2004. Apesar da existência de inúmeros estudos sobre a leishmaniose visceral humana e canina, muitas lacunas ainda precisam ser preenchidas.

Chronic interstitial pneumonitis in dogs naturally infected with Leishmania (Leishmania) chagasi: a histopathological and morphometric study

Eighteen mongrel dogs of unknown age and naturally infected with Leishmania (Leishmania) chagasi, were obtained from the City Hall of Belo Horizonte, Brazil. Four dogs were used as control. Lung samples were obtained and immediately fixed in formalin. The histopathological picture of all lung tissue sections was a chronic and diffuse interstitial pneumonitis. The thickened inter-alveolar septa were characterized by the cellular exudate (mostly macrophages, lymphocytes and plasmocytes) associated with collagen deposition. Morphometric analysis showed greater septal thickness in the infected animals than in controls. In fact, the morphometric study of collagen stained with ammoniac silver confirmed a larger deposition of collagen in the infected animals. The parasitologic method was carried out during the study of the lesions on the slides. However, we did not observe any correlation between the histopathologic and morphometric data and the clinical status of the animals. We conclude that the pulmonary lesions observed in all naturally infected dogs were correlated with the disease and that the morphometric method used was satisfactory for the analysis of septal thickness and of increased collagen deposition, confirming the presence of fibrosis

Identification and purification of immunogenic proteins from nonliving promastigote polyvalent Leishmania vaccine (Leishvacin®)

Immunogenic proteins from nonliving promastigote polyvalent Leishmania vaccine against American tegumentary leishmaniasis (Leishvacin®), produced by Biobrás (Biochemistry of Brazil ), Montes Claros, State of Minas Gerais, Brazil, were identified and purified by polyacrylamide electrophoresis gel and electroelution. C57BL/10 mice were vaccinated with proteins with estimated molecular weights of 42, 46, 63, 66, 73, 87, 97, and 160kDa in three doses of 30æg of each protein at 15-day intervals combined with 250æg of Corynebacterium parvum followed by a challenge infection with 10(5) infective promastigotes from Leishmania (Leishmania) amazonensis. The ability of these proteins to induce immune response and protection was analyzed. No statistical difference was observed in the level of IFN-g induced by proteins in vaccinated groups in comparison with control groups. Six months after challenge infection, protection levels of 28.57; 42.86; 57.14; 42.86; 42.86, 57.14; 42.86 and 57.14 percent were demonstrated for each purified protein

Concurrent cutaneous, visceral and ocular leishmaniasis caused by Leishmania (Viannia) braziliensis in a kidney transplant patient

Although cases of leishmaniasis co-infection have been described in acquired immunodeficiency syndrome patients as well as those who have undergone organ transplants, to our knowledge, the present report is the first documented case of simultaneous cutaneous, visceral and ocular leishmaniasis due to Leishmania (Viannia) braziliensis in a transplant patient. The patient had been using immunosuppressive drugs since receiving a transplanted kidney. The first clinical signs of leishmaniasis included fever, thoracic pain, hepatosplenomegaly, leucopenia and anemia. The cutaneous disease was revealed by the presence of amastigotes in the skin biopsy. After three months, the patient presented fever with conjunctive hyperemia, intense ocular pain and low visual acuity. Parasites isolated from iliac crest, aqueous humor and vitreous body were examined using a range of molecular techniques. The same strain of L. (V.) braziliensis was responsible for the different clinical manifestations. The immunosuppressive drugs probably contributed to the dissemination of Leishmania

Influence of microbiota in experimental cutaneous leishmaniasis in Swiss mice

Neste trabalho, estudamos a infeccao experimental de camundongos Suicos/NIH com Leishmania major em comparacao com camundongos isogenicos C57BL/6 e BALB/c que sao resistentes e suceptiveis a esta infeccao, respectivamente. Camundongos Suicos mostraram lesoes que se curaram espontaneamente e se restringiram ao local de inoculacao. Celulas linfoides derivadas destes animais desenvolveram uma resposta do tipo Th1, caracterizada pela producao de niveis altos de IFN-gama e niveis baixos de IL-4. Com o objetivo de estudar a importancia da microbiota no desenvolvimento da leishmaniose cutanea neste modelo, camundongos Suicos sem germes foram infectados na pata com promastigotas de L. major, convencionalizados apos 3 semanas de infeccao e as lesoes comparadas com as observadas em camundongos convencionais...

Immune responses induced by a Leishmania (Leishmania) amazonensis recombinant antigen in mice and lymphocytes from vaccinated subjects

A resposta imune induzida por uma proteina recombinante de Leishmania (Leishmania) amazonensis de 33 kD (Larp33) foi avaliada em linfocitos de individuos vacinados com a Leishvacin e em camundongos atraves de vacinacao. Larp33 foi expressa em Escherichia coli apos clonagem de um fragmento genomico de L. (L.) amazonensis de 2,2 kb no vetor pDS56-6His. Larp33 foi reconhecida por anticorpos IgG presentes no soro de individuos vacinados com Leishvacin e induziu proliferacao em linfocitos desses individuos em niveis comparaveis ao antigeno total de Leishmania...

Tratamento da leishmaniose tegumentar americana utilizando vacina / Treatment of american cutaneous leishmaniasis by means of vaccine

Foi realizado o tratamento de 62 pacientes portadores de leishmaniose tegumentar utilizando como agente imunoterápico uma vacina constituída de promastigotas mortas. O esquema terapêutico utilizado mostrou ser uma alternativa adequada ao tratamento de leishmaniose tegumentar já que houve sucesso terapêutico em 75,8% dos casos, näo se observando efeitos colaterais. A eficiência terapêutica foi semelhante nos casos de lesöes cutâneas ou mucosas

Distinctions between promastigotes of Leishmania species developing in the digestive tract of laboratory reared Lutzomyia longipalpis

Female Lutzomya longipalpis were exposed to infection by three different species/strains of Leishmania. When the insects were dissected four days after exposure, stained preparations were made of the flagellates contained in the digestive tract. Using traditional morphometric methods, L. amazonensis, L. guyanensis and an unnamed species of the mexicana complex could be distinguished from one another

Susceptibility of laboratory-reared female Lutzomyia longipalpis (Lutz & Neiva, 1912) to infection by different species and strains of Leishmania Ross, 1903

A study was undertaken to compare the susceptibility of laboratory-reared female Lutzomyia longipalpis to infection by different species or strains of New World Leishmania. The sand flies proved to be highly susceptible to infection by a strain of Le. guyanensis, with flagellates developing in all (18/18) of the specimens examined. A lower infection rate of 37 per cents (10/27) was recorded in flies exposed to infection by a strain of Le. amazonensis. Flagellates developed in 13 per cents (6/46) of the sand flies that glood fed on dogs in the earlly stage of experimental infection with an old laboratory strain of Le. chagasi. In contrast, promastigotes did not develop in sand flies that blood fed on dogs with naturally acquired Le. chagasi. The naturally infected dogas were in an advanced stage of disease. Flagellates developed in 9// (3/32) of the sand flies that blood fed on lesions of hamsters infected with a strain of Le. braziliensis and in 9 per cents (3/34) of those that fed on hamsters with lesions due to a parasite fo the mexicana complex (strain MHOM/BR/73/BH121). Sand flies did not develop flagellate infections after blood feeding on hamsters bearing lesions induced by strain MHOM/BR/71/BR49. Factors influencing the susceptibility of Lu. longipalpis to infection by New World species of Leishmania are discussed