Prevalence and incidence of canine visceral leishmaniasis and its clinical-immunological features in an endemic area of the Brazilian Amazon

BACKGROUND

A cohort study for 2 years period analysed the prevalence, incidence and clinical-immunological features of canine Leishmania (L.) chagasi-infection in 316 mongrel dogs in a visceral leishmaniasis-endemic area in Pará State, Brazil.

OBJECTIVE/METHODS

Diagnosis of infection was performed by the indirect fluorescent antibody test (IFAT-IgG), the leishmanin skin test (LST) and a parasite search (from the popliteal lymph node aspiration) at the beginning of the study and at 6, 12 and 24 months intervals.

RESULTS

IFAT/LST revealed three immune profiles of infection: (I) IFAT(+) /LST(-) (81), (II) IFAT(-) /LST(+) (17) and (III) IFAT(+) /LST(+) (13). Prevalence of profiles I, II and III were 25.6, 5.4 and 4.1%, and an overall prevalence 35.1%. Incidence of profiles I, II and III were 5.4, 0.3 and 0.0%, and an overall incidence 5.7% dogs per month. Incidence at the age ranges <1 year, ≥1 year, <7 years and ≥7 years evidenced a highest rate in the age range <1 year (6.6% dogs per month). Parasitological diagnosis was positive in 19% dogs at the prevalence (85.7% profile I), and in 11% at the incidence (100% profile I). The clinical picture of 179 infected dogs showed 145 (81%) of profile I (82% subclinical); 21 (11.7%) of profile II (100% subclinical); and 13 (7.3%) of profile III (84.6% subclinical). Conversion from subclinical to sick dogs was higher (p < 0.05) in profile I (40.2%) than in profiles II (5.8%) and III (9%). Immunological conversion showed that only 3.2% of profile I dogs (prevalence) converted to LST(+) (two at the end of the first 6 months and 1 after 24 months), while 82.3% of profile II dogs converted to IFAT(+) (11 in the first 6 months, whereas three after 12 months). A 100% death rate was observed in dogs from profile I alone.

CONCLUSION

These results reinforce the need of adopting preventive strategies against CVL as early as in the first semester of the dog's life.

Leishmania (L.) infantum chagasi isolated from skin lesions of patients affected by non-ulcerated cutaneous leishmaniasis lead to visceral lesion in hamsters

In Central America, Leishmania (L.) infantum chagasi infection causes visceral leishmaniasis (VL) and non-ulcerated cutaneous leishmaniasis (NUCL). The aim of the present study was to evaluate the course of an experimental infection in hamsters caused by L. (L.) infantum chagasi isolated from patients affected by NUCL compared with a strain isolated from a patient with VL. Stationary phase parasites in culture were inoculated through subcutaneous and intraperitoneal routes in hamsters. Following the post-infection times, a histopathological study, parasite load and cytokine determination in skin from the cutaneous inoculation site and viscera were performed. Animals subcutaneously infected with the different strains did not develop macroscopic lesions at the inoculation site, and the histopathological changes in the dermis were very slight. Regarding the histopathological study of the viscera, we observed the portal mononuclear inflammatory infiltrate, the presence of nodules in the hepatic parenchyma and the proliferation of macrophages in the spleen, which increased over the infection course. Overall, the parasite load in the liver and spleen and in the total IgG titres in the sera of infected hamster showed an increase with the time of infection, regardless of the route of inoculation. Regarding cellular immunity, we did not observe an increase or decrease in pro- and anti-inflammatory cytokines compared to the healthy control, except for IL-10, which was evident in the infected animals. The data showed that strains isolated from NUCL cause visceral lesions in the hamsters regardless of the route of inoculation, and they were similar to parasites isolated from VL humans.

Gene Signatures of Symptomatic and Asymptomatic Clinical-Immunological Profiles of Human Infection by Leishmania (L.) chagasi in Amazonian Brazil

Individuals infected with Leishmania (L.) chagasi may present different asymptomatic and symptomatic stages of infection, which vary in the clinical–immunological profiles that can be classified as asymptomatic infection (AI), subclinical resistant infection (SRI), indeterminate initial infection (III), subclinical oligosymptomatic infection (SOI), and symptomatic infection (SI) (=American visceral leishmaniasis, AVL). However, little is known about the molecular differences between individuals having each profile. Here, we performed whole-blood transcriptomic analyses of 56 infected individuals from Pará State (Brazilian Amazon), covering all five profiles. We then identified the gene signatures of each profile by comparing their transcriptome with those of 11 healthy individuals from the same area. Symptomatic individuals with SI (=AVL) and SOI profiles showed higher transcriptome perturbation when compared to those asymptomatic III, AI and SRI profiles, suggesting that disease severity may be associated with greater transcriptomic changes. Although the expression of many genes was altered on each profile, very few genes were shared among the profiles. This indicated that each profile has a unique gene signature. The innate immune system pathway was strongly activated only in asymptomatic AI and SRI profiles, suggesting the control of infection. In turn, pathways such as MHC Class II antigen presentation and NF-kB activation in B cells seemed to be specifically induced in symptomatic SI (=AVL) and SOI profiles. Moreover, cellular response to starvation was down-regulated in those symptomatic profiles. Overall, this study revealed five distinct transcriptional patterns associated to the clinical–immunological (symptomatic and asymptomatic) profiles of human L. (L.) chagasi-infection in the Brazilian Amazon.

Role of antigen-presenting cells in non-ulcerated skin lesions caused by Leishmania (Leishmania) infantum chagasi

In Central America, infection by Leishmania (Leishmania) infantum chagasi causes visceral leishmaniasis and non-ulcerated cutaneous leishmaniasis (NUCL). This work aimed to evaluate the participation of subpopulations of antigen-presenting cells in skin lesions of patients affected by NUCL through double-staining immunohistochemistry using cellular and intracellular markers. Twenty-three skin biopsies from patients affected by NUCL were used. Histological sections stained by HE were used for histopathological study. Immunohistochemical studies were performed using primary antibodies against Langerhans cells, dermal dendritic cells, T lymphocytes, and the cytokines IL-12, IFN-γ, TNF-α, iNOS, and IL-10. The histopathological lesions were characterized by an inflammatory infiltrate, predominantly lymphohistiocytic, of variable intensity, with a diffuse arrangement associated with epithelioid granulomas and discreet parasitism. Double-staining immunohistochemistry showed higher participation of dendritic cells producing the proinflammatory cytokine IL-12 in relation to the other evaluated cytokines. Activation of the cellular immune response was marked by a higher density of CD8 Tc1-lymphocytes followed by CD4 Th1-lymphocytes producing mainly IFN-γ. The data obtained in the present study suggest that antigen-presenting cells play an important role in the in situ immune response through the production of proinflammatory cytokines, directing the cellular immune response preferentially to the Th1 and Tc1 types in NUCL caused by L. (L.) infantum chagasi.

In situ expression of Th17 immunologic mediators in American cutaneous leishmaniasis caused by Leishmania (V.) braziliensis and Leishmania (L.) amazonensis in the Brazilian Amazon

American cutaneous leishmaniasis (ACL) presents a wide spectrum of clinical and immunopathological manifestations. In Brazil, Leishmania (L.) amazonensis[La] and Leishmania(V.)braziliensis[Lb] show the highest pathogenic potential for humans causing different clinical forms: localized cutaneous leishmaniasis (LCL : Lb/La), anergic diffuse cutaneous leishmaniasis (ADCL : La) and mucocutaneous leishmaniasis (MCL : Lb). ADCL and MCL are the most severe forms and infection leads to a cellular immune response at the hyposensitivity and hypersensitivity poles. Th17-cells are involved in the ACL pathogenesis, are derived from naïve TCD4+ cells regulated by RORγt, differentiate in presence of IL-6, TGF-β, IL- 1β, IL-23 and express IL-17. Aim of this study was to characterize the cellular immune response mediated by Th17-profile cells through in situ determination of the expression of RORγt, IL-17, IL-6, TGF-β, IL-1β, and IL-23 in the ACL clinical-immunopathological spectrum caused by L.(L.)amazonensis and L.(V.)braziliensis. Biopsies of skin and mucosal lesions from forty patients including ADCL(n=8), LCL[La](n=17), LCL[Lb](n=9) and MCL(n=6), were examined by immunohistochemistry. The immunostained cells density (cells/mm2) was determined in image analysis system using AxionVision 4.8 software (Zeiss). As the disease evolution time (DET) was different among ACL patients, the effect of DET on the expression of immunological markers was evaluated in different clinical forms and histopathological changes, using ANCOVA. Our results showed significantly increased expression of RORγt, IL-17, IL-6, IL-1β and IL-23 in patients with ACL polar forms (ADCL and MCL); higher TGF-β expression was found in ADCL. DET influenced the expression of RORγt and IL-6 in: clinical forms of ACL and in categories of parasitism. DET also affected the production of RORγt, IL-17, IL-6, TGF-β and IL-1β in types of inflammatory infiltrate, evidencing that DET had effect on the expression of Th17 profile cytokines in ACL. Together, the expression of immunological mediators of Th17 profile in the ACL spectrum, as well as the DET effect, demonstrate the participation of this cell lineage in the immunopathogenesis of ACL, mainly in the polar and more severe forms of ACL spectrum. The dubious role played by Th17-cells may favors immune response suppression and parasitic persistence in ADCL, while in MCL it contributes to an exacerbated immune response and parasite scarcity.

Molecular tools confirm natural Leishmania (Viannia) guyanensis/L. (V.) shawi hybrids causing cutaneous leishmaniasis in the Amazon region of Brazil

Seven isolates from patients with American cutaneous leishmaniasis in the Amazon region of Brazil were phenotypically suggestive of Leishmania (Viannia) guyanensis/L. (V.) shawi hybrids. In this work, two molecular targets were employed to check the hybrid identity of the putative hybrids. Heat shock protein 70 (hsp70) gene sequences were analyzed by three different polymerase chain reaction (PCR) approaches, and two different patterns of inherited hsp70 alleles were found. Three isolates presented heterozygous L. (V.) guyanensis/L. (V.) shawi patterns, and four presented homozygous hsp70 patterns involving only L. (V.) shawi alleles. The amplicon sequences confirmed the RFLP patterns. The high-resolution melting method detected variant heterozygous and homozygous profiles. Single-nucleotide polymorphism genotyping/cleaved amplified polymorphic site analysis suggested a higher contribution from L. (V.) guyanensis in hsp70 heterozygous hybrids. Additionally, PCR-RFLP analysis targeting the enzyme mannose phosphate isomerase (mpi) gene indicated heterozygous and homozygous cleavage patterns for L. (V.) shawi and L. (V.) guyanensis, corroborating the hsp70 findings. In this communication, we present molecular findings based on partial informative regions of the coding sequences of hsp70 and mpi as markers confirming that some of the parasite strains from the Brazilian Amazon region are indeed hybrids between L. (V.) guyanensis and L. (V.) shawi.

Phlebotomines (Diptera: Psychodidae) from a Urban Park of Belém, Pará State, Northern Brazil and Potential Implications in the Transmission of American Cutaneous Leishmaniasis

In urban ecotourism parks, the life cycle of American cutaneous leishmaniasis (ACL) agents can remain established, where phlebotomines may comprise potential risks for visitors. The present study aimed to survey the phlebotomine fauna of a forest park 'Bosque Rodriques Alves-Jardim Botânico da Amazônia' (BRAJBA), in the urban area of Belém, Brazil. The park was monthly surveyed in 2018 using CDC light traps placed in ground and canopy strata. Leishmania spp. isolated from dissected females were characterized by polymerase chain reaction-restriction fragment length polymorphism analysis (PCR-RFLP) analysis. Fluctuations in specimen capture were correlated with rainfall. Nyssomyia antunesi (Coutinho, 1939) was predominant for all surveyed ecotopes and capture methods in both areas. Females of Ny. antunesi resting on tree bases were observed attempting to bite researchers during early morning. One Bichromomyia flaviscutellata (Mangabeira, 1942) and one Trichophoromyia brachipyga (Mangabeira, 1942) were found naturally infected by flagellates. Only the strain from Th. brachipyga was isolated and characterized as Leishmania (Viannia) lainsoni Silveira, Shaw, Braga and Ishikawa, 1987. Monthly fluctuations of the three most abundant species, Ny. antunesi, Trichophoromyia ubiquitalis (Mangabeira, 1942) and Th. brachypiga, had statistically significant negative correlations with rainfall. The present study provided further information to better understand ACL ecology in the Belém urban area, where the urban parks surveyed appeared to offer potential risk of contracting the disease, thus requiring environmental management. These observations highlighted the need for including Ny. antunesi, Bi. flaviscutellata, Th. ubiquitalis, and Th. brachypiga in the priority list for continuous entomological surveillance.

What makes mucosal and anergic diffuse cutaneous leishmaniases so clinically and immunopathogically different? A review in Brazil

American cutaneous leishmaniasis (ACL) is a parasitic protozoan disease caused by different Leishmania species widely distributed throughout Latin America. Fifteen Leishmania species belonging to the subgenera Viannia, Leishmania and Mundinia are known to cause ACL. Seven of these species are found in Brazil, of which Leishmania (Viannia) braziliensis and Leishmania (Leishmania) amazonensis have the highest potential to cause mucosal (ML) and anergic diffuse cutaneous leishmaniasis (DCL), respectively, the most severe forms of ACL. The clinical and immunopathological differences between these two clinical forms are reviewed here, taking into account their different physiopathogenic mechanisms of dissemination from cutaneous lesions to mucosal tissues in the case of ML and to almost all body surfaces in the case of anergic DCL. We also discuss some immunopathogenic mechanisms of species-specific Leishmania antigens (from the subgenera Viannia and Leishmania) that are most likely associated with the clinical and immunopathological differences between ML and anergic DCL. Those discussions emphasize the pivotal importance of some surface antigens of L. (V.) braziliensis and L. (L.) amazonensis, such as lipophosphoglycan, phosphatidylserine and CD200 (an immunoregulatory molecule that inhibits macrophage activation), that have been shown to exert strong influences on the clinical and immunopathological differences between ML and anergic DCL.

Host and parasite responses in human diffuse cutaneous leishmaniasis caused by L. amazonensis

Diffuse cutaneous leishmaniasis (DCL) is a rare form of leishmaniasis where parasites grow uncontrolled in diffuse lesions across the skin. Meta-transcriptomic analysis of biopsies from DCL patients infected with Leishmania amazonensis demonstrated an infiltration of atypical B cells producing a surprising preponderance of the IgG4 isotype. DCL lesions contained minimal CD8+ T cell transcripts and no evidence of persistent TH2 responses. Whereas localized disease exhibited activated (so-called M1) macrophage presence, transcripts in DCL suggested a regulatory macrophage (R-Mϕ) phenotype with higher levels of ABCB5, DCSTAMP, SPP1, SLAMF9, PPARG, MMPs, and TM4SF19. The high levels of parasite transcripts in DCL and the remarkable uniformity among patients afforded a unique opportunity to study parasite gene expression in this disease. Patterns of parasite gene expression in DCL more closely resembled in vitro parasite growth in resting macrophages, in the absence of T cells. In contrast, parasite gene expression in LCL revealed 336 parasite genes that were differently upregulated, relative to DCL and in vitro macrophage growth, and these transcripts may represent transcripts that are produced by the parasite in response to host immune pressure.

Entomological surveys of Lutzomyia flaviscutellata and other vectors of cutaneous leishmaniasis in municipalities with records of Leishmania amazonensis within the Bragança region of Pará State, Brazil

In southeast Amazon, Lutzomyia (Nyssomyia) flaviscutellata is the incriminated vector of Leishmania (Leishmania) amazonensis, a causative agent of zoonotic cutaneous leishmaniasis (CL). The optimal methods for surveying Lu. flaviscutellata were investigated in the Bragança region, northeast Pará State, Brazil, selected for the presence of Le. amazonensis. The performances of modified Disney traps and CDC light traps were compared in four ecotopes within and around four village transects during the wet and dry seasons. The physiological age of female sand flies was estimated and natural infection by flagellates was evaluated by dissection. Disney traps were better for detecting the presence of Lu. flaviscutellata, while CDC traps performed well for detecting Lutzomyia (Nyssomyia) antunesi, suspected vector of Leishmania lindenbergi. The former was more abundant during the wet season, when female flies were naturally infected with Le. amazonensis. These findings identified the environments of local transmission. In order to improve surveys of Lu. flaviscutellata as part of integrated epidemiological surveillance of CL, our recommendations include focusing vector surveys with Disney traps on forest fragments where people work, during the seasonal peak of the vector. Further field studies are required to make model-based predictions of seasonal variations in the vectorial capacity of vector populations.

Canine leishmaniasis: Genome-wide analysis and antibody response to Lutzomyia longipalpis saliva

The anti-inflammatory properties of sand fly saliva favor the establishment of the Leishmania infantum infection. In contrast, an antibody response against Lutzomyia longipalpis saliva is often associated with a protective cell-mediated response against canine visceral leishmaniasis. Genetic studies may demonstrate to what extent the ability to secrete anti-saliva antibodies depends on genetic or environmental factors. However, the genetic basis of canine antibody response against sand fly saliva has not been assessed. The aim of this study was to identify chromosomal regions associated with the anti-Lu. longipalpis salivary IgG response in 189 dogs resident in endemic areas in order to provide information for prophylactic strategies. Dogs were classified into five groups based on serological and parasitological diagnosis and clinical evaluation. Anti-salivary gland homogenate (SGH) IgG levels were assessed by Enzyme-Linked Immunosorbent Assay (ELISA). Genomic DNA was isolated from blood samples and genotyped using a SNP chip with 173,662 single nucleotide polymorphism (SNP) markers. The following linear regression model was fitted: IgG level = mean + origin + sex + age + use of a repellent collar, and the residuals were assumed as pseudo-phenotypes for the association test between phenotypes and genotypes (GWA). A component of variance model that takes into account polygenic and sample structure effects (EMMAX) was employed for GWA. Phenotypic findings indicated that anti-SGH IgG levels remained higher in exposed and subclinically infected dogs than in severely diseased dogs even in regression model residuals. Five associated markers were identified on chromosomes 2, 20 and 31. The mapped genes included CD180 (RP105) and MITF related to the rapid activation of B lymphocytes and differentiation into antibody-secreting plasma cells. The findings pointed to chromosomal segments useful for functional confirmation studies and a search for adjuvant molecules of the anti-saliva response.

Further evidence associating IgG1, but not IgG2, with susceptibility to canine visceral leishmaniasis caused by Leishmania (L.) infantum chagasi-infection

We present here a cross-sectional study analyzing the IgG1 and IgG2 immune responses to natural canine Leishmania (L.) infantum chagasi-infection and their relationships with delayed-type hypersensitivity (DTH) in 50 mongrel dogs with previous positive serodiagnoses (IFAT-IgG) (56% with subclinical status [= apparently healthy] and 44% clinically sick), living in endemic areas for visceral leishmaniasis in the Brazilian Amazon. IgG1 and IgG2 responses were measured using commercial polyclonal antibodies in ELISA, while DTH was elicited by intradermal skin test using cultured promastigotes L. (L.) i. chagasi-antigen. Data analyses used Chi-square and Pearson's r coefficient (95% confidence interval). Regarding DTH and the clinical statuses of dogs, it was noted that 100% of the animals showing positive DTH (n = 8) were from the subclinical group, while 100% showing negative DTH were from the clinically sick group; higher IgG2 than IgG1 responses were observed in both clinical groups. However, when this comparison was made between the subclinical and sick groups, higher IgG1 responses were noted in the dogs from the sick rather than the subclinical group, while no differences were noted between the IgG2 responses in the dogs from both clinical groups. Additionally, we found lower IgG1 responses in dogs from the subclinical group showing positive DTH than in the dogs from the subclinical or sick groups with negative DTH; no differences were found between the IgG2 responses of these two clinical groups. These findings suggest that the IgG1, but not the IgG2, response is associated with susceptibility to canine visceral leishmaniasis (CVL).

Salivary gland homogenates from wild-caught sand flies Lutzomyia flaviscutellata and Lutzomyia (Psychodopygus) complexus showed inhibitory effects on Leishmania (Leishmania) amazonensis and Leishmania (Viannia) braziliensis infection in BALB/c mice

During the natural transmission of Leishmania parasites, the infected sand fly female regurgitates promastigotes into the host's skin together with its saliva. It has been reported that vector saliva contains immunomodulatory molecules that facilitate the establishment of infection. Thus, the main objective of this study was to evaluate the specificity of Lutzomyia (Lu.) flaviscutellata and Lu. (Psychodopygus) complexus salivas on the infectivity of Leishmania (L.) (Leishmania) amazonensis and L. (Viannia) braziliensis, respectively. BALB/c mice were inoculated into the skin of hind footpad with L. (L.) amazonensis and L. (V.) braziliensis promastigotes in the absence or presence of Lu. flaviscutellata and Lu. (P.) complexus salivary gland homogenates (SGHs). The evolution of the infection was evaluated by lesion size, histopathological analysis and determination of the parasite load in the skin biopsies collected from the site of infection at 4 and 8 weeks PI. The lesion size and the parasite load of both groups of mice infected in the presence of SGHs were smaller than the control groups. The histopathological features showed that the inflammatory reaction was less prominent in the groups of mice infected in the presence of both SGHs when compared to the control group. The results showed that the presence of SGHs of Lu. flaviscutellata and Lu. (P.) complexus led to induction of processes that were disadvantageous to parasite establishment during infection by L. (L.) amazonensis and L. (V.) braziliensis. An inhibitory effect on Leishmania infection could be observed in both groups inoculated with SGHs, especially when the SGH from Lu. (P.) complexus was used.

Leishmania (V.) braziliensis and L. (L.) amazonensis promote differential expression of dendritic cells and cellular immune response in murine model

The expression of Langerhans cell (LC) and dermal dendritic cell (dDC) as well as T CD4(+) and CD8(+) immune responses was evaluated in the skin of BALB/c mice experimentally infected by L. (L.) amazonensis (La) and L. (V.) braziliensis (Lb). At 4th and 8th weeks post infection (PI), skin biopsies were collected to determine the parasite load and CD207(+), CD11c(+), CD4(+), CD8(+), iNOS(+) cellular densities. Cytokine (IFN-γ, IL-4 and IL-10) profiles were also analysed in draining lymph node. At 4th week, the densities of CD207(+) and CD11c(+) were higher in the La infection, while in the Lb infection, these markers revealed a significant increase at 8th week. At 4th week, CD4(+) and CD8(+) were higher in the La infection, but at 8th week, there was a substantial increase in both markers in the Lb infection. iNOS(+) was higher in the Lb infection at 4th and 8th weeks. In contrast, the parasite load was higher in the La infection at 4th and 8th weeks. The concentration of IFN-γ was higher in the Lb infection, but IL-4 and IL-10 were higher in the La infection at 4th and 8th weeks. These results confirm the role of the Leishmania species in the BALB/c mice disease characterized by differences in the expression of dendritic cells and cellular immune response.

A cross-sectional study on canine Leishmania (L.) infantum chagasi infection in Amazonian Brazil ratifies a higher prevalence of specific IgG-antibody response than delayed-type hypersensitivity in symptomatic and asymptomatic dogs

This was a cross-sectional study which analyzed the prevalence and the clinical and immunological spectrum of canine Leishmania (L.) infantum chagasi infection in a cohort of 320 mongrel dogs living in an endemic area of American visceral leishmaniasis in the Amazonian Brazil by using, mainly, the indirect fluorescence antibody test (IFAT-IgG) and the delayed-type hypersensitivity (DTH), and the parasite research by the popliteal lymph node aspiration. The IFAT and DTH reactivity recognized three different immune response profiles: (1) IFAT((+))/DTH((-)) (107 dogs), (2) IFAT((-))/DTH((+)) (18 dogs), and (3) IFAT((+))/DTH((+)) (13 dogs), providing an overall prevalence of infection of 43% (138/320). Thus, the specific prevalence of IFAT( (+) )/DTH( (-) ) 33.4% (107/320) was higher than those of IFAT( (-) )/DTH( (+) ) 5.6% (18/320) and IFAT( (+) )/DTH( (+) ) 4.0% (13/320). Moreover, the frequency of these profiles among 138 infected dogs showed that the IFAT( (+) )/DTH( (-) ) rate of 77.5% (107/138) was also higher than those of 13.0% (18/138) of IFAT( (-) )/DTH( (+) ) and 9.5% (13/138) of IFAT( (+) )/DTH( (+) ) rates. The frequency of asymptomatic dogs (76%-105) was higher than those of symptomatic (16.6%-23) and oligosymptomatic ones (7.4%-10). A total of 16 (11.6%) L. (L.) i. chagasi isolates were obtained from infected dogs, all from the IFAT( (+) ) /DTH( (-) ) profile: 41% (9/22) from symptomatic, 33.3% (3/9) from oligosymptomatic, and 5.2% (4/76) from asymptomatic dogs. These findings strongly suggested that despite the higher frequency of asymptomatic dogs (76%-105), the majority (72.4%-76) was characterized by the IFAT( (+) ) /DTH( (-) ) profile with a doubtful immunogenetic resistance against infection.

Immunopathogenic competences of Leishmania (V.) braziliensis and L. (L.) amazonensis in American cutaneous leishmaniasis

The immunopathogenic competences of Leishmania (V.) braziliensis and L. (L.) amazonensis were reviewed in the light of more recent features found in the clinical and immunopathological spectrum of American cutaneous leishmaniasis. It was shown a dichotomy in the interaction between these Leishmania species and human T-cell immune response; while L. (V.) braziliensis shows a clear tendency to lead infection from the localized cutaneous leishmaniasis (LCL), a moderate T-cell hypersensitivity form at the centre of the spectrum, toward to the mucocutaneous leishmaniasis (MCL) at the T-cell hypersensitivity pole and with a prominent Th1-type immune response, L. (L.) amazonensis shows an opposite tendency, leading infection to the anergic diffuse cutaneous leishmaniasis (ADCL) at the T-cell hyposensitivity pole and with a marked Th2-type immune response. Between the central LCL and the two polar MCL and ADCL, the infection can present an intermediary form known as borderline disseminated cutaneous leishmaniasis, characterized by an incomplete inhibition of T-cell hypersensitivity but with a evident supremacy of Th1 over Th2 immune response (Th1 > or = Th2). These are probably the main immunopathogenic competences of L. (V.) braziliensis and L. (L.) amazonensis regarding the immune response dichotomy that modulates human infection outcome by these Leishmania parasites.

A cross-sectional study on the clinical and immunological spectrum of human Leishmania (L.) infantum chagasi infection in the Brazilian Amazon region

The objectives of this study were to identify individuals with symptomatic and/or asymptomatic infection due to Leishmania (L.) infantum chagasi; to study the two types of infection, both clinically and immunologically, and to determine the prevalence rate of infection at the beginning of the study. This was a cross-sectional study with a cohort of 946 individuals, of both genders, from the age of 1 year, living in the municipality of Barcarena, PA, Brazil, an area endemic for American visceral leishmaniasis (AVL). The leishmanin skin test (LST) and the indirect fluorescent test (IFAT), were used for the diagnosis of infection. One hundred and twenty cases of infection were diagnosed, with a prevalence rate of 12.6%; eight cases showed high seroreactivity (1280-10240, IgG) in IFAT and no LST reaction; four of these cases were typical AVL and four had subclinical oligosymptomatic infection. Using two immunological methods with a clinical examination of the infected individuals enabled the identification of five clinical-immunological profiles which may promote a better understanding of the interaction between L. (L.) i. chagasi and the human immune response: asymptomatic infection (AI) 73.4%; subclinical resistant infection (SRI) 15%; subclinical oligosymptomatic infection (SOI) 3%; symptomatic infection (AVL) 3% and indeterminate initial infection (III) 5%.

A longitudinal study on the transmission dynamics of human Leishmania (Leishmania) infantum chagasi infection in Amazonian Brazil, with special reference to its prevalence and incidence

This was a longitudinal study carried out during a period over 2 years with a cohort of 946 individuals of both sexes, aged 1 year and older, from an endemic area of American visceral leishmaniasis (AVL) in Pará State, Brazil. The object was to analyze the transmission dynamics of human Leishmania (Leishmania) infantum chagasi infection based principally on the prevalence and incidence. For diagnosis of the infection, the indirect fluorescent antibody test (IFAT) and leishmanin skin test (LST) were performed with amastigote and promastigote antigens of the parasite, respectively. The prevalence by LST (11.2%) was higher (p < 0.0001) than that (3.4%) by IFAT, and the combined prevalence by both tests was 12.6%. The incidences by LST were also higher (p < 0.05) than those by IFAT at 6 (4.7% x 0.6%), 12 (4.7% x 2.7%), and 24 months (2.9% x 0.3%). Moreover, there were no differences (p > 0.05) between the combined incidences by both tests on the same point surveys, 5.2%, 6.3%, and 3.6%. During the study, 12 infected persons showed high IFAT IgG titers with no LST reactions: five children and two adults developed AVL (2,560-10,120), and two children and three adults developed subclinical oligosymptomatic infection (1280-2560). The combined tests diagnosed a total of 231 cases of infection leading to an accumulated prevalence of 24.4%.

Observations on Eimeria species of Dasyprocta leporina (Linnaeus, 1758)(Rodentia: Dasyproctidae) from the state of Pará, North Brazil

Redescriptions are given of the mature oocysts of Eimeria aguti Carini 1935, E. cotiae Carini, 1935 and E. paraensis Carini, 1935, in the faeces of five specimens of the rodent Dasyprocta leporina (Rodentia: Dasyproctidae) from the state of Pará, North Brazil. New information is provided on the sporulation time of these parasites and the prepatent period in experimentally infected D. leporina. Some endogenous stages of E. cotiae are described in the epithelial cells of the ileum, and the absence of any oocysts in the gall-bladder contents of the infected animals indicates that the intestine is also the site of development of E. aguti and E. paraensis. Difficulties in separating E. cotiae and E. paraensis on morphology of the oocysts are discussed. The oocysts of both parasites share many structural features and have a wide size range. It is concluded that although it is at present best to maintain these names, the possibility exists that they were separately given to oocysts of smaller dimensions (E. cotiae) and larger dimensions (E. paraensis) of a single parasite. Location of an endogenous site of development for E. paraensis that is distinctly separate from that of E. cotiae might establish more definitely the separate specific status of the two parasites.

Parasites of the squirrel Sciurus spadiceus (Rodentia: Sciuridae) from Amazonian Brasil, with particular reference to Eimeria damnosa n. sp. (Apicompiexa: Eimeriidae)

A description is given of the mature oocysts and endogenous stages of Eimeria damnosa n. sp. from the small intestine of the red squirrel, Sciurus spadiceus, from the State of Acre, north Brazil. Ten of 12 animals examined were infected. Oocysts ovoid to ellipsoidal, occasionally cylindrical but not with parallel sides, 30.2 x 20.0 microm (18.0 x 15.0-40.2 x 30.0), shape-index (ratio length/width) 1.5 (1.3-1.8), n = 40. Oocyst wall smooth, colourless, with no micropyle, apparently of a single layer measuring approximately 1.0-1.5 microm thick. No oocyst residuum, but approximately 50 % of the oocysts with a single spherical, ovoid or dumbbell-shaped polar body. Sporocysts pear-shaped, 15.0 x 8.0 microm (11.0 x 6.0-16.0 x 8.0), shape index 1.9 (1.8-2.0), n = 33. Stieda body, if it merits this name, appears only as a slight thickening of the sporocyst wall at the more pointed extremity. Endogenous stages intracytoplasmic in the epithelial cells of the duodenum and throughout the ileum, above the host cell nucleus. Sporulation frequently completed in the lumen of the intestine, but most oocysts mature outside the host at some time within 24 hours. Massive infections may result in extensive desquamation of the gut epithelium, and sometimes in the death of the animal. In addition to this coccidian, one squirrel showed abundant trophozoites of a Giardia sp., in the ileum. The liver of two others contained developing and mature meronts, producing large numbers of slender merozoites, and other cyst-like bodies containing a small number of large zoites (sporozoites?). No parasites were detected in the blood of any of the squirrels that could be associated with this unidentified protozoan. Histological sections of the ileum of one squirrel revealed a globidium-like parasite in the lamina propria: it contained a very large number of slender, curved zoites. Three animals were with a sheathed microfilaria in the peripheral blood and liver smears. Finally, a Trypanosoma cruzi-like trypanosome was isolated from the blood of one squirrel and a T. lewisi-like trypanosome from two others.

Further observations on clinical, histopathological, and immunological features of borderline disseminated cutaneous leishmaniasis caused by Leishmania (Leishmania) amazonensis

Leishmania (Leishmania) amazonensis has for some time been considered as the causative agent of two distinct forms of American cutaneous leishmaniasis (ACL): localized cutaneous leishmaniasis (LCL), and anergic diffuse cutaneous leishmaniasis (ADCL). Recently, a new intermediate form of disease, borderline disseminated cutaneous leishmaniasis (BDCL), was introduced into the clinical spectrum of ACL caused by this parasite, and in this paper we record the clinical, histopathological, and immunological features of eight more BDCL patients from Brazilian Amazonia, who acquired the disease in the Pará state, North Brazil. Seven of them had infections of one to two years' evolution and presented with primary skin lesions and the occurrence of metastases at periods varying from six to 12 months following appearance of the first lesion. Primary skin lesions ranged from 1-3 in number, and all had the aspect of an erythematous, infiltrated plaque, variously located on the head, arms or legs. There was lymphatic dissemination of infection, with lymph node enlargement in seven of the cases, and the delayed hypersensitivity skin-test (DTH) was negative in all eight patients prior to their treatment. After that, there was a conversion of DTH to positive in five cases re-examined. The major histopathological feature was a dermal mononuclear infiltration, with a predominance of heavily parasitized and vacuolated macrophages, together with lymphocytes and plasma cells. In one case, with similar histopathology, the patient had acquired his infection seven years previously and he presented with the largest number of disseminated cutaneous lesions. BDCL shows clinical and histopathological features which are different from those of both LCL and ADCL, and there is a good prognosis of cure which is generally not so in the case of frank ADCL.

Clinical and immunopathological spectrum of American cutaneous leishmaniasis with special reference to the disease in Amazonian Brazil: a review

The wide variety of Leishmania species responsible for human American cutaneous leishmaniasis combined with the immune mechanisms of the host results in a large spectrum of clinical, histopathological, and immunopathological manifestations. At the middle of this spectrum are the most frequent cases of localized cutaneous leishmaniasis (LCL) caused by members of the subgenera Leishmania and Viannia, which respond well to conventional therapy. The two pathogenicity extremes of the spectrum generally recognized are represented at the hypersensitivity pole by mucocutaneous leishmaniasis (MCL) and at the hyposensitivity pole by anergic diffuse cutaneous leishmaniasis (ADCL). Following the present study on the clinical, histopathological and immunopathological features of cutaneous leishmaniasis in Amazonian Brazil, we propose the use of the term "borderline disseminated cutaneous leishmaniasis" for the disseminated form of the disease, due to parasites of the subgenera Leishmania and Viannia, which might be regarded as intermediate between LCL and the extreme pathogenicity poles MCL and ADCL.

American visceral leishmaniasis: wild animal hosts

In Colombia it has been suggested that the rodent Proechimys canicollis may be a reservoir-host of Leishmania (L.) chagasi, the cause of American visceral leishmaniasis, based on polymerase chain reaction/hybridization tests. We have detected no infection in laboratory-bred specimens of another species, P. guyannensis, after their inoculation with promastigotes or amastigotes of this parasite from Amazonian Brazil.

Genetic variation in populations of Leishmania species in Brazil

The population structure of strains of Leishmania (Viannia) braziliensis sensu lato from Pará State and Paraná State in Brazil, of L. (V.) shawi and L. (Leishmania) amazonensis from Pará State, and the relationships of type strains of the subgenera L. (Viannia) and L. (Leishmania) were examined by the random-amplified polymorphic deoxyribonucleic acid (RAPD) technique. Four different primers (M13-40, QG1, L15996 and delta gt11R) were used. The bands were analysed using the neighbor-joining (NJ) and unweighted pair-group method with arithmetic averages (UPGMA) algorithms of the MEGA package. The topology of the NJ and UPGMA trees was very similar but they were not always identical. Both trees differentiated the standard strains of the different species. Strains from the same location were grouped together only in the UPGMA phenogram of the M13-40 primer. L. (V.) braziliensis isolates from Paraná State were genetically closer to those from Paragominas, Pará State than to those from the Amazonian regions of Carajás in Pará State and Peru. The relationship was not dependent on geographical distance. It is postulated that the groups arose from different origins, in which the Amazonian stocks were related to Psychodopygus sand flies while the Paraná strains originated from a gene pool transmitted by Lutzomyia sand flies such as Lutzomyia (Nyssomyia) whitmani. Transmission by Ps. complexus in Paragominas is considered to be a secondary adaptation from the Lutzomyia leishmanial gene pool. Although the vectors of L. (V.) braziliensis are poorly known in the Amazon region, there is strong evidence that the major vectors are all Psychodopygus spp. There was a high degree of genetic variability amongst the L. (V.) shawi strains and there was no clear grouping according to the strains' origins. The genetic variability amongst L. (L.) amazonensis strains from the same locations was much lower but they formed 2 groups which coincided with their origin. Our results support the clonal population structure of Leishmania isolates and suggest that their distribution is related to the origin of the gene pool as well as to present vector and reservoir movements.

An outbreak of cutaneous leishmaniasis among soldiers in Belém, Pará State, Brazil, caused by Leishmania (Viannia) lindenbergi n. sp. A new leishmanial parasite of man in the Amazon region

Eight cases of cutaneous leishmaniasis are recorded among soldiers of the Brazilian Forest Infantry stationed in Belém, State of Pará, north of Brazil. The infections, all acquired during manoeuvres in nearby degraded primary forest, are attributed to a new member of the subgenus Viannia, Leishmania (V.) lindenbergi n. sp. A further infection by this parasite was encountered in a woman, who lived very close to the same piece of forest. The new parasite has been characterised and differentiated from other known species of the subgenus Viannia following the combined use of enzyme electrophoresis and monoclonal antibodies techniques. The eco-epidemiology of L. (V.) lindenbergi is discussed: by far the most abundant anthropophilic sandfly in the type locality was identified as Lutzomyia (Nyssomyia) antunesi (Coutinho), and this remains high on the list of possible vectors.

T cell responses to crude and defined leishmanial antigens in patients from the lower Amazon region of Brazil infected with different species of Leishmania of the subgenera Leishmania and Viannia

Amazonian localized cutaneous leishmaniasis (LCL) is caused by parasites of the subgenera Leishmania and Viannia. Respectively, these parasites may cause diffuse cutaneous leishmaniasis (DCL) and mucocutaneous leishmaniasis (MCL). This, together with differing skin test responses, suggests some species-specificity in cell mediated immunity. In this study, T cell responses (proliferative and interferon-gamma) to crude and defined antigens were examined in paired samples pre and post chemotherapy. Untreated L. (L.) amazonensis LCL patients showed lower responses to crude leishmanial antigens than the L. (V.) spp. group. L. (V.) braziliensis antigen was a more potent stimulator of T cell responses than L. (L.) amazonensis antigen in all patient groups. Few positive responses were seen to the L. (L.) amazonensis glycoprotein GP46. A substantial proportion of LCL patients did respond to the L. (L.) pifanoi amastigote antigens A2, and the surface membrane glycoprotein P8. DCL patients were poor responders to all leishmanial antigens, except GP46. In contrast, MCL patients were good responders to all antigens except GP46 and A2. A significant rise in the response to P8 and A2 antigen was seen post treatment across all LCL and MCL patients, indicating that these antigens might provide suitable vaccine candidates.

Experimental cutaneous leishmaniasis. IV. The humoral response of Cebus apella (Primates: Cebidae) to infections of Leishmania (Leishmania) amazonensis, L. (Viannia) lainsoni and L. (V.) braziliensis using the direct agglutination test

The direct agglutination test (DAT) was used to evaluate the serological response of 150 serum samples taken from 15 captive-bred capuchin monkeys Cebus apella. These animals had been experimentally infected with either L. (Leishmania) amazonensis, L. (Viannia) lainsoni or L. (V.) braziliensis. Monkeys infected with L. (L.) amazonensis or L. (V.) lainsoni were challenged with the homologous parasite one month after their spontaneous cure. DAT antigens were prepared from L. (L.) donovani, L. (L.) amazonensis and L. (V.) braziliensis. Antigens were difficult to standardise and it was impossible to produce an L. (V.) lainsoni antigen as parasites remained aggregated even after trypsinization. The DAT detected significant humoral responses in all the infected monkeys. Titres were higher when homologous antigens were used, especially in secondary responses. This suggests that homologous antigen should be used to detect antibodies in human cutaneous leishmaniasis.

[Direct agglutination tests in the serodiagnosis of visceral leishmaniasis in the state of Pará]

The direct agglutination test (DAT) was evaluated for serodiagnosis of visceral leishmaniasis (VL) in human and canids (dogs and foxes Cerdocyon thous). The results were compared with those of the immunofluorescent antibody assay (IFAT) and enzyme-linked immunosorbent assay (ELISA). The sera used were from: humans (303): confirmed VL (16), suspected VL (65), other conditions (102), negative controls (15) and individuals from an endemic area (105); dogs (82): from an endemic area (68), Salvaterra/Marajó/Pará (21 of which were parasitologically positive), and negative controls (14), from Belém; foxes (9): caught on Marajó Island. Antigens for DAT were prepared from promastigots of L. (L.) donovani, L. (L.) chagasi. Antigens used in ELISA and IFAT were prepared from promastigotes (soluble antigen) and amastigotes respectively of L. (L.) chagasi. In humans, the specificity and sensitivity of DAT using L. (L.) donovani were high (98.4% and 100% respectively) and comparable to that of IFAT (97.5% and 100%). ELISA was less specific (84.8%) although similarly sensitive (100%). In dogs, DAT was more specific using L. (L.) donovani as antigen than using L. (L.) chagasi. However, both DAT and ELISA were less sensitive (both 71.4%) than IFAT (100%). This difference was reflected in the results from endemic dogs, 87% of which were positive by IFAT but only 54% by ELISA and 49% by DAT. Similarly, all 9 fox sera were positive by IFAT, 7 of 9 (78%) by ELISA but none by DAT. In conclusion, DAT using L. (L.) donovani antigen can provide a useful test for human VL; utilization on a large scale would be possible with a suitable reference laboratory to monitor antigen quality. However, DAT appears less useful for canine studies, as it was less sensitive than ELISA and especially IFAT in detecting canine infection.

[Histopathology of the localized form of cutaneous leishmaniasis caused by Leishmania (Leishmania) amazonensis]

The microscopic changes found in the localized form of the human cutaneous leishmaniasis due to Leishmania (Leishmania) amazonensis are reported. In this form, less known than the diffuse one caused by the same species, the clinical manifestations are identical to those produced by other Leishmania species of the subgenus Viannia. There is, however, in the localized infection by L. (L.) amazonensis, a peculiar feature, only recently discovered: about 50% of the affected individuals are Montenegro-negatives. The main histologic change observed in the skin sections was the presence of groups of macrophages with a large vacuole in the cytoplasm, containing many amastigotes. The microscopic picture is similar to that found in the diffuse form of the disease, the difference being only quantitative. When in large numbers, the macrophages suffers necrosis, which generally starts at the center of the groups. First, in this process, the membrane of the parasitized cells ruptures, and the amastigotes become free; later, both cells and parasites are destroyed. The picture can be seen either in Montenegro-negative or in Montenegro-positive patients. The macrophages with amastigotes may persist in tissues for as long as 6-7 months, while in the infections due to L. (V.) braziliensis the parasites usually disappear in a few weeks.

Human hydatidosis in the population of endemic regions of the Rio Grande do Sul state, Brazil

The incidence of human hydatidosis in South Brazil was evaluated in the areas of intensive ovine breeding. A total of 325 persons from two counties of an endemic area were evaluated by serological tests. Two positive cases (1.6%) were found in the county of Santana do Livramento and also two cases (1%) in the county of Bagé. The percentage of persons with antibodies against the hydatic cyst is high and higher than official statistics.

The dermal leishmaniases of Brazil, with special reference to the eco-epidemiology of the disease in Amazonia

Six species of Leishmania are at present known to cause cutaneous and/or mucocutaneous leishmaniasis in Brazil, and they are all to be found in the Amazon region of this country. The eco-epidemiology of each is discussed, with the observation that the Amazonian leishmaniases are all zoonoses, with their source in silvatic mammals and phlebotomine sandfly vectors. With man's destruction of the natural forest in southern Brazil, some sandfly species have survived by adapting to a peridomestic or domiciliary habitat in rural areas. Some domestic animals, such as dogs and equines are seemingly now involved in the epidemiology of the disease. No such process has yet been reported in the Amazon region, but may well take place with the continuing devastation of its forest.

Zigomicose nasofacial: relato de um caso do estado do Pará, Brasil

Um caso de zigomicose nasofacial, causado por Conidiobolus coronatus, é descrito em paciente de 64 anos, do sexo feminino, procedente de Barcarena, Estado do Pará. Trata-se de doença rara na Região Norte do país - a maioria dos casos brasileiros tem sido registrada em Estados da Região Nordeste -, e o achado confirma a ocorrência do agente no Estado do Pará. A resposta ao iodeto de potássio, droga administrada à paciente, logo após a comprovação do diagnóstico pelo isolamento do fungo, foi boa, com resolução parcial das lesões em algumas semanas. A paciente continua ainda em tratamento, tendo-se associado o itraconazol ao iodeto

[Nasofacial zygomycosis. Report of a case of Para state, Brazil]

A case of nasofacial zygomycosis in a 64-year-old female patient from Barcarena, State of Pará, is reported. This is the second time that the disease is recognized in Northern Brazil. The diagnosis was initially suspected by the direct observation of broad coenocytic hyphae in biopsy specimens of the nasal cavity mucosa. Later, the cause of the disease was confirmed by the mycologial and histopathological findings. Rapid response to the therapy with potassium iodide was achieved, without however a complete resolution of the lesions. The patient still remains under treatment, with itraconazole and iodide.

Avaliação de três esquemas terapêuticos com o antimoniato de N-metil-glucamina no tratamento da leishmaniose visceral no estado do Pará, Brasil

Avaliaram-se, de forma retrospectiva, três esquemas terapêuticos à base do antimoniato de N-metil-glucamina (Glucantime) usados no tratamento de 43 casos autóctones de leishmaniose visceral (Estado do Pará), observados em crianças de 1 a 12 anos de idade, no período de 1985 a 1990. Dos 43 casos, 28 (grupo A) foram tratados com 40 mg/SbV/kg administrados IV a intervalos de 48 hs, em séries de 15 doses (esquema I); 8 (grupo B) receberam 40mg/SbV/kg administrados IV diariamente, durante 15 dias (esquema II), e 7 (grupo C) receberam 20 mg/SbV/kg administrados IV diariamente, durante 15 dias (esquema III). Considerando que o controle de cura da doença foi essencialmente clínico, admitiu-se que o esquema III representaria a melhor opção terapêutica, em razão de: a) ter promovido taxa de cura equivalente aos esquemas que usaram o dobro dessa dose, b) a relação custo-benefício desse esquema torna-o menos dispendioso, c) pode ser usado durante período mais prolongado, com menor risco de produzir efeitos de toxicidade, e d) não existem, a nível local (Pará), relatos de casos de resistência da doença associados ao uso desse esquema.

[Evaluation of 3 therapeutic schedules with N-methyl-glucamine antimonate in the treatment of visceral leishmaniasis in the state of Para, Brazil]

We have evaluated, in a retrospective manner, three chemotherapeutic schemes with meglumine antomoniate (Glucantime) use in the treatment of 43 autochthonous cases of visceral leishmaniasis in children in the age-group of 1-12 years old, during the period 1985-1990. Of the 43 cases, 28 (group A) were treated with 40mg/SbV/kg given IV at intervals of 48 hours, in courses of 15 applications (scheme I); 8 (group B) were treated with 40 mg/SbV/kg given IV daily during 15 days (scheme II), and 7 (group C) were treated with 20 mg/SbV/kg given IV daily during 15 days (scheme III). With the criteria for cure based essentially on clinical examination, we admitted that the scheme III would be the preferred for these reasons: a) it produces the same cure-rate as those schemes which use double this dosage, b) in relation to positive results it is less expensive, c) the scheme can be used for more extended periods, with less risk of toxic effects, and d) there has till now been no evidence of the development of resistance to treatment using this scheme, at least in our particular area of study (Pará).

Cutaneous leishmaniasis due to Leishmania (Leishmania) amazonensis in Amazonian Brazil, and the significance of a negative Montenegro skin-test in human infections

The clinical and epidemiological features of 62 cases of cutaneous leishmaniasis due to Leishmania (Leishmania) amazonensis, from Pará State, Amazonian Brazil, are discussed. The parasite, isolated in hamster skin and/or blood-agar culture medium, was in each case identified by both biological characteristics and a monoclonal antibody specific for promastigotes of L. (L.) amazonensis. Of the 62 patients, 46 (74.2%) presented with a single cutaneous lesion, and on no occasion was evidence found indicating metastatic spread to either the naso-pharyngeal mucosae or the viscera. Recent claims that this parasite may be responsible for both mucocutaneous leishmaniasis and typical visceral leishmaniasis are discussed. Meglumine antimoniate (Glucantime) proved highly efficient in the treatment of all patients. Of the 62 patients examined by the Montenegro skin test, only 32 (51.6%) gave a positive reaction. The significance of this finding is considered and the hypothesis made that the parasite itself may induce an immunoinhibition. Field studies amply confirmed the role of Lutzomyia flaviscutellata as the major sandfly vector of L. (L.) amazonensis in Amazonia.

[Cutaneous leishmaniasis in Amazonia: isolation of Leishmania (Viannia) lainsoni from the rodent Agouti paca (Rodentia: Dasyproctidae), in the state of Pará, Brazil]

The isolation of Leishmania (V.) lainsoni is recorded for the first time from a wild animal, the rodent Agouti paca (Rodentia: Dasyproctidae), from Pará State, north Brazil. Isolates of the parasite were made from apparently normal skin of 3 specimens of this rodent captured on the Island of Tocantins, in the municipality of Tucuruí, an area subsequently flooded in the formation of the lake associated with the Tucuruí hydroelectric dam. No isolations were made from the viscera. Identification of the parasite was in each case based on morphology of the amastigotes and promastigotes, behavior of the organism in hamsters, isoenzymes profiles and the use of monoclonal antibodies. The inapparent nature of the infection leads us to suggest that the "paca", Agouti paca, represents a primitive host of L. (V.) lainsoni in the Amazon Region.

Cutaneous leishmaniasis of man due to Leishmania (Viannia) shawi Lainson, de Souza, Póvoa, Ishikawa & Silveira, in Pará State, Brazil

Leishmania (Viannia) shawi Lainson, Braga, de Souza, Póvoa, Ishikawa & Silveira, 1989, was originally recorded from monkeys (Cebus apella and Chiropotes satanas), sloths (Choloepus didactylus and Bradypus tridactylus) and coatis (Nasua nasua) and the sandfly, Lutzomyia whitmani. With a panel of Leishmania specific monoclonal antibodies, it was found that 30.5% of the Leishmania strains from patients, who had contracted cutaneous leishmaniasis in Pará State, were similar, but not identical to L. (V.) guyanensis. The enzyme profiles of 18 of these strains were determined, and it was found that 12 isolates belonged to the same zymodeme as the type strain of L. (V.) shawi. The other 6 belonged to a second L. (V.) shawi zymodeme that only differed from the other by having a slightly faster PEP band. These results are the first records of infections of L. (V.) shawi in man and suggest that this parasite is probably common in areas of Pará State to the south of the Amazon River.

[Experimental cutaneous leishmaniasis. III. Histopathological aspects of the developmental behavior of the cutaneous lesion induced in Cebus apella (Primates: Cebidae) by Leishmania (Viannia) lainsoni, L. (V.) braziliensis and L. (Leishmania) amazonensis]

We have studied the histopathological aspects related to the evolution of cutaneous lesions experimentally produced in the monkey Cebus apella (Primates: Cebidae) by Leishmania (V.) lainsoni, L. (V.) braziliensis and L. (L.) amazonensis. Microscopical examination of a series of biopsies obtained from these animals showed the kinetics of the cutaneous lesions regarding three species of Leishmania inoculated, as follows: 1) an initial non-specific chronic inflammatory infiltrate; 2) macrophagic nodules; 3) necrosis of parasitized phagocytic cells; 4) epitheliode granuloma; 5) absorption of the necrotic area (sometimes forming "foreign-body granuloma"); 6) a non-specific residual inflammatory infiltration; and 7) cicatrization. These pathological processes are, of course, responsible for both development and resolution of the leishmaniotic lesion. We also discuss some immunopathological mechanisms probably related with the sequential events, and that could be also responsible for the different clinical aspects found in man.

[Experimental skin leishmaniasis: II--course of the infection in the Cebus apella primate (Cebidae) caused by Leishmania (V.) braziliensis and L. (L.) amazonensis]

As a means of assessing the usefulness of the monkey Cebus apella as an experimental model for the study of cutaneous leishmaniasis, 5 of these animals were inoculated intradermally at 8 sites along the tail with 3 X 10(6) promastigotes of L. (V.) braziliensis, while a further 5 monkeys received similar inoculations with 3 X 10(6) promastigotes of L. (L.) amazonensis. Following the inoculations, weekly examinations and monthly biopsies showed evolution of resulting skin lesions to be as follows: a) L. (V.) braziliensis: lesions were first visible 15-20 days post-inoculation (p.i), and at 30 days they were clearly of an erythematous-papular nature, which assumed a nodular form at 60 days; after 3 months a spontaneous ulceration of these lesions was noted and, at 4 months, the initiation of healing. In one animal total healing was apparent 5 months p.i; in two others at 6 months, in another monkey after 7 months, and in the last animal at 10 months p.i. Amastigotes were demonstrated in smears from the lesions of all monkeys up to 90 days p.i; up to 120 days in two animals, and at 180 days p.i. in the monkey which showed resolution of the lesions after 10 months. b) L. (L.) amazonensis lesions were first apparent after 20 days p.i; at 30 days they were of an erythematous-papular nature, developing into nodules at 60 days. From the third month of infection onwards, however, the lesions diminished rapidly and, at 90 days p.i. amastigotes were no longer detectable in the skin.(ABSTRACT TRUNCATED AT 250 WORDS)