Cutaneous leishmaniasis: an evolving disease with ancient roots.

BACKGROUND: Cutaneous leishmaniasis (CL) remains a prioritized neglected tropical disease. CL novel presentations call for updating its features. METHODS: A multiregional cohort of 396 patients with confirmed CL was reviewed. Lesion's clinical stage and eruption type were assigned. Disease was considered as extensive if numerous (≥5), large (>3 cm), disfiguring, threatening vital sensory organs, and/or older than 12 months. Microscopically, Ackerman's inflammatory pattern, Ridley's pattern (RP), and parasitic index (PI) were recorded. Microscopic variables pertaining to the organisms, epidermis, and host's inflammatory response were also assessed. All cases were confirmed and speciated molecularly. RESULTS: In our region, 71.8% of cases showed extensive disease with 15.7% exceeding 12 months duration. Leishmania tropica accounted for 91.3% of cases while Leishmania major constituted 8.7% and presented solely as dry lesions. The dominant inflammatory composite consisted of plasma cells, lymphocytes, and histiocytes. Granulomatous inflammation was present in 55.5%. Most cases showed interface changes (72.7%), spongiosis (75.3%), and marked epidermal hyperplasia (63.9%). Transepidermal elimination of organisms was present in 29.2% of cases. None of traditional classification patterns (clinical stage, microscopic pattern, and RP) showed the predicted linear correlation with lesion age. High and low PI levels correlated with early and healing microscopic patterns, respectively, but did not correlate with the corresponding RPs. PI was bimodal with peaks at 3-6 and 9-12 months. CONCLUSION: Cutaneous leishmaniasis is an evolving disease defying the traditional prediction classifications. Our study sets the ground for adopting updated clinical courses, microscopic presentation, and species mapping.

Flow cytometric assessment of Leishmania spp metacyclic differentiation: validation by morphological features and specific markers.

Characterization of infective metacyclic promastigotes of Leishmania spp can be an essential step in several experimental protocols. Metacyclic forms of all Leishmania species display a typical morphology with short, narrow cell body, and an elongated flagellum. This feature suggests that metacyclics can be distinguished from procyclic forms by non-fluorimetric flow cytometric parameters thus enabling the follow-up of their appearance and acquisition of specific properties, during metacyclogenesis in in vitro cultures. Here we describe the flow cytometric parameters of stage-specific promastigotes of Leishmania major, Leishmania donovani, Leishmania amazonensis, and Leishmania braziliensis. Our findings were validated by optical microscopy morphology and specific procyclic labeling with FITC-peanut agglutinin. Furthermore, we show that parasite's distribution in the plot during differentiation in culture is not species specific and that the parasites displaying low forward-angle light scatter (FSC(low)) are three times more infective than the FSC(high) ones. The method here described can be applied to the identification of metacyclics of different Leishmania spp within the whole stationary population.

A new standard for the assessment of disease progression in murine cutaneous leishmaniasis.

Infection of mice with Leishmania major has been used both as a model for the cutaneous disease in humans and as a model for the more general control and function of helper T cells in immunity. In both cases, disease patterns and disease progression have been assessed by two complementary methods, lesion size and parasite burden in the draining lymph nodes. We propose a much improved method for the graphical representation of lesion development which conveys more information with better accuracy. We also describe a polymerase chain reaction method for determining parasite burden, which is faster and allows the analysis of larger numbers of experimental animals than the current limiting dilution analysis. Moreover, these methods are equally applicable to other infectious diseases, an obvious one being schistosomiasis.