Evaluation of leishmanin skin test reaction in different variants of cutaneous leishmaniasis

Abstract

Introduction:Cutaneous leishmaniasis (CL) is a parasitic disease which has different clinical forms. The aim of this study is to compare the response to leishmanin skin test (LST) in three forms of CL including plaque type, lupoid type, and sporotrichoid type.Materials and Methods:This was a descriptive cross-sectional study. The patients enrolled in this study had three clinical forms of CL confirmed by positive smear of their lesions and then LST was performed for them. Results were categorized as negative (0-5 mm induration), positive (6-14 mm), and strongly positive (≥15 mm). The data were documented in the patients’ files and analyzed with SPSS windows software version 16 (Inc.Chicago, USA).Results:200 patients were enrolled in the study. In the group with plaque type, 86% had a positive LST, 13.3% were negative, and 0.7% were strongly positive. In the lupoid group, these figures were 45.8%, 8.4%, 45.8%, respectively. In the sporotrichoid group, LST was positive in 27.3%, negative in 72.7%, and none of the patients had a strongly positive reaction (P < 0.05). Discussion: The most of the positive LST were belong to plaque and lupoid groups, the most of strongly positive were belong to lupoid, and the most of negative LST were related with sporotrichoid type.Conclusion:It can be suggested that lupoid and sporotrichoid types of CL are parts of a continuous spectrum of the disease with an enhanced cellular immunity in lupoid form and a decreased state in sporotrichoid type.

Reevaluating leishmanin skin test as a marker for immunity against cutaneous leishmaniasis

“…LST provokes this immune response by reintroducing Leishmania antigens into the skin with a positive result being interpreted as a sign of previous infection by the Leishmania parasite; the test has been used as a diagnostic tool for leishmaniasis for the past 50 years . Based on current evidence, LST conversion following infection occurs within few days to a few months . The test has acceptable sensitivity and very high specificity (85% and 100%, respectively) and thus a positive result can be interpreted as previous exposure to the parasite with very high accuracy .…”

“…9 Based on current evidence, LST conversion following infection occurs within few days to a few months. 10 The test has acceptable sensitivity and very high specificity (85% and 100%, respectively) and thus a positive result can be interpreted as previous exposure to the parasite with very high accuracy. 4,11 Furthermore, the immune response mechanism of the test has been previously inferred as resistance towards reinfection by Leishmania parasites; this assumption has formed the basis of vaccine development efforts thus far, which have aimed to render individuals LST positive.…”

Tissue damage and immunity in cutaneous leishmaniasis

“…Other studies have used leishmanin skin test (LST), which is a classical delayed hypersensitivity test, where parasite antigen is injected intradermally and responses in terms of tissue swelling and inflammation is determined after a few days. Self‐healing lesions are associated with antigen‐specific T‐cell responses and a positive LST reaction . T cells from patients with MCL are hyperresponsive to antigenic stimulation and LTS reactions large, reflecting on an aggressive effector T‐cell response , while patient with DCL fail to generate antigen‐specific response and often are LST negative .…”

Sporotrichoid Cutaneous Leishmaniasis in Central Tunisia: Epidemiological and Clinical Aspects

“…The factors that trigger lymphatic dissemination are unclear but some data suggest that the host immune status could influence this dissemination [10,11]. Indeed, Sadeghian et al [20] showed that the leishmanin skin test (LST) was negative in 72% of SF cases and that none was strongly positive in LST positive patients. They concluded that the SF of CL is at least partially due to a decrease in cellular immunity.…”