[Cutaneous leishmaniasis: clinical and immunopathological aspects]

DNA sequencing confirms the involvement of Leishmania (L.) amazonensis in American tegumentary leishmaniasis in the state of São Paulo, Brazil

INTRODUCTION

American tegumentary leishmaniasis (ATL) represents one of the most important public health issues in the world. An increased number of autochthonous cases of ATL in the Northeastern region of São Paulo State has been documented in the last few years, leading to a desire to determine the Leishmania species implicated.

METHODS

PCR followed by DNA sequencing was carried out to identify a 120bp fragment from the universal kDNA minicircle of the genus Leishmania in 61 skin or mucosal biopsies from patients with ATL.

RESULTS

DNA sequencing permitted the identification of a particular 15bp fragment (5' GTC TTT GGG GCA AGT... 3') in all samples. Analysis by the neighbor-joining method showed the occurrence of two distinct groups related to the genus Viannia (V) and Leishmania (L), each with two subgroups. Autochthonous cases with identity to a special Leishmania sequence not referenced in Genbank predominated in subgroup V.1, suggesting the possible existence of a subtype or mutation of Leishmania Viannia in this region. In the subgroup L.2, which showed identity with a known sequence of L. (L.) amazonensis, there was a balanced distribution of autochthonous and non-autochthonous cases, including the mucosal and mucocutaneous forms in four patients. The last observation may direct us to new concepts, since the mucosal compromising has commonly been attributed to L. (V.) braziliensis, even though L. (L.) amazonensis is more frequent in the Amazonian region.

CONCLUSIONS

These results confirm the pattern of distribution and possible mutations of these species, as well as the change in the clinical form presentation of ATL in the São Paulo State.

Perfil histopatológico e imuno-histoquímico da leishmaniose tegumentar americana com ênfase nos dendrócitos dérmicos FXIIIa+

FUNDAMENTOS: Leishmaniose tegumentar é doença parasitária infecciosa que apresenta aspectos imunológicos relevantes. OBJETIVO: Estudar a histopatologia e aspectos imuno-histoquímicos de 21 biópsias de leishmaniose tegumentar. MÉTODOS: Anticorpo policlonal anti-Leishmania foi utilizado para identificação das leishmânias. A classificação histopatológica adotada foi em grupos padrões de I a V. Foram analisados os dendrócitos dérmicos FXIIIa+, células de Langerhans CD1a+, macrófagos CD68+, linfócitos B CD20+ e T CD3+. As células FXIIIa+ foram quantificadas na derme papilar e comparadas a peles normais obtidas de área não exposta à luz solar, sendo o número de células FXIIIa+ avaliado estatisticamente através do teste de Mann-Whitney. As demais células foram contadas semiquantitativamente. RESULTADOS: Entre os grupos histopatológicos, predominaram os I e II. Não houve diferença estatisticamente significante (p=0,157) entre o número de células FXIIIa+ na leishmaniose e na pele normal. Não foi observada diferença si ificante entre a presença das células CD1a+, CD68+, CD20+ e CD3+, quando comparadas entre si ou com as células FXIIIa+. CONCLUSÃO: Não houve diferença no número de células dendríticas FXIIIa+ entre a leishmaniose e pele normal. No entanto, sugere-se que mais estudos sejam necessários para se entender o papel dessas células na leishmaniose.

The susceptibility of domestic cats (Felis catus) to experimental infection with Leishmania braziliensis

Over the last few years, several cases of feline leishmaniasis (FL) with cutaneous and visceral forms have been reported around the world. Nonetheless, the real susceptibility of cats to infection with Leishmania spp. and the outcome of leishmaniasis in these animals are poorly understood. Experimental studies on feline models will contribute to the knowledge of natural FL. Thus, in order to determine the susceptibility of domestic cats (Felis catus) to experimental infection with Leishmania braziliensis, 13 stray cats were infected with 10(7) promastigotes by the intradermal route in the ear and nose simultaneously and followed up for 72 weeks. Soon after infection, the earliest indication of a lesion was a papule on the ear at 2 weeks post-infection (w.p.i.). The emergence of satellite papules around the primary lesion was observed about 4 w.p.i. Two weeks later these papules coalesced and formed a huge and irregular nodule. Thereafter, there was lesion dissemination to the external and marginal surface of the ipsilateral ear, and later to the contralateral ear. At 10 w.p.i., some nodules became ulcerated. Nose lesions presented a similar evolution. At both sites, the largest lesion sizes occurred at 10 w.p.i. and started to decrease 15 days later. Ear and nose nodules healed at 32 and 40 w.p.i., respectively. Specific L. braziliensis IgG antibody titers (optical density> or = 0.01 as positive result) were detected as early as 2 w.p.i. (0.09 +/- 0.02) in only three animals (23%), and all cats had positive titers at 20 w.p.i. (0.34 +/- 0.06). Only three animals (38%) continued to show positive serology at 72 w.p.i. (0.08 +/- 0.02). Up to that time, none of the cats had lesion recurrence. In a feline model of cutaneous leishmaniasis, it seems that there is no correlation between active lesions and positive serology. The implications of these data are discussed.

Experimental infection of canine peritoneal macrophages with visceral and dermotropic Leishmania strains

A study was carried out using macrophages cultured from the peritoneal exudate of dogs infected in vitro with three species of Leishmania: L. (L.) chagasi, L. (Viannia) braziliensis and L. (L.) amazonensis with the aim of investigating the growth kinetics and infectivity of these species in the host cell. Results were expressed as the percentage of macrophages infected measured at 24 hr intervals over six days in RPMI - 1640 culture medium at a temperature of 34-35 degrees C. The findings open the possibility of using canine peritoneal cells as a model for the screening of leishmanicide drugs and to study the pathogenesis of these species.

[Cases of american cutaneous leishmaniasis caused by Leishmania (Viannia) braziliensis in the towns of Cosmópolis and Indaiatuba-region of Campinas, in São Paulo, Brazil]

A study was carried out to identify Leishmania species involved in skin lesions of patients from Cosmópolis and Indaiatuba, State of São Paulo, Brazil. The epidemiological data of cutaneous leishmaniasis in two cities suggested a epidemic situation in 1994. The lesions were clinically characteristic of cutaneous leishmaniasis and five out six patients responded positively to Montenegro's intradermal test. The histopathology of skin lesions were characterized by two patterns: exudative-cellular reaction and exudative granulomatous reaction. The clinical and histopathological parameters suggested Leishmania (Viannia) braziliensis as the possible etiologic agent. In agreement, it was difficult to isolate and maintain the parasite in the laboratory. Characterization by in situ hybridization with kDNA amastigotes from lesions fragments confirmed that Leishmania (Viannia) braziliensis was the parasite responsible for the studied cutaneous lesions.

Leishmaniasis recidiva cutis in American cutaneous leishmaniasis

BACKGROUND

Leishmaniasis recidiva cutis (LRC) consists of active lesions around or inside the scar of classical cutaneous leishmaniasis (CL). In the literature it is considered as an hyperergic form of CL because the patients show a strong response to intradermal testing with leishmania antigen and, histologically, the parasites are scarce or absent; a well-organized granuloma is always observed.

METHODS

Three patients from Bahia (Brazil) with LRC were evaluated by clinical examination, biopsies, skin tests with leishmania antigen, serology, and culture. In addition, a specific lymphocyte blastogenesis test was done and the species of leishmania characterized.

RESULTS

The disease was caused by both L. amazonensis and L. braziliensis and serological titers varied from 1/16 to 1/64. The patients presented histologic and immunologic aspects different from those referred to in the literature. From four biopsies obtained only two presented a granulomatous reaction and parasites varied from absent to a parasite index 3. In one patient an absence of T cell response to leishmania antigen was observed in the first evaluation with restoration of the response after cure. In the other two, the degree of the specific proliferative response was lower than that usually observed in patients with classical CL.

CONCLUSIONS

These findings indicate that New World LRC can not be considered a hyperergic form of CL. With respect to its clinical aspects and response to treatment, LRC must be considered as an entity different from the classical CL.

Mucosal leishmaniasis ("espundia" Escomel, 1911)

One of the more serious clinical forms of leishmaniasis occurs in espundia when the mucosae of the upper respiratory passages are inflamed. This complication is a metastasis from a skin lesion caused by Leishmania braziliensis braziliensis (Lbb) although cases have been described associated with other leishmanial species. Epidemiological data suggest that a detectable mucosal metastasis occurs in fewer than 5% of patients infected with Lbb in our study area. The determinants of this complication are still largely obscure. The granuloma usually commences on the nasal septum. In about two-thirds of our patients the lesion remained restricted to the nose. In the rest the pharynx, palate, larynx and lips were involved, in this order. It is often difficult to isolate the parasite and for routine diagnosis the leishmanin skin reaction and serological tests are helpful. Although a serious condition, with possible mutilation and even death as subsequent complications, treatment is still mainly with pentavalent antimonials, introduced 40 years ago. These are most unsatisfactory for field use, being given parenterally and relatively toxic. In mucosal leishmaniasis, if sufficient antimony can be administered in a regular daily dose, the relapse rate is small (3 of 42 patients followed for a mean of 5 years). Also, antimony treatment of the initial skin ulcer due to Lbb followed for a mean of 4 years of 83 patients resulted in subsequent mucosal metastasis in only 2. Since espundia is relatively rare, specific treatment targeted to this specific problem is the efficient short term solution. At present there is no satisfactory alternative drug to those in current use.