Leprosy: a review of laboratory and therapeutic aspects - Part 2

Abstract

Leprosy is a chronic infectious condition caused by Mycobacterium leprae(M. leprae). It is endemic in many regions of the world and a public health problem in Brazil. Additionally, it presents a wide spectrum of clinical manifestations, which are dependent on the interaction between M. leprae and host, and are related to the degree of immunity to the bacillus. The diagnosis of this disease is a clinical one. However, in some situations laboratory exams are necessary to confirm the diagnosis of leprosy or classify its clinical form. This article aims to update dermatologists on leprosy, through a review of complementary laboratory techniques that can be employed for the diagnosis of leprosy, including Mitsuda intradermal reaction, skin smear microscopy, histopathology, serology, immunohistochemistry, polymerase chain reaction, imaging tests, electromyography, and blood tests. It also aims to explain standard multidrug therapy regimens, the treatment of reactions and resistant cases, immunotherapy with bacillus Calmette-Guérin (BCG) vaccine and chemoprophylaxis.

Detection of <em>Mycobacterium leprae</em> using real-time PCR in paucibacillary leprosy patients with negative acid-fast bacilli smears

“…protein. 4 However, this serological test often gives falsenegative results due to a low number of bacilli or low antibody levels. 4 The sensitivity of the serological test on PB-type leprosy ranges only between 15% and 40%.5 Therefore, serological testing is not recommended for diagnosing PB-type leprosy due to its low sensitivity.…”

“…4 However, this serological test often gives falsenegative results due to a low number of bacilli or low antibody levels. 4 The sensitivity of the serological test on PB-type leprosy ranges only between 15% and 40%.5 Therefore, serological testing is not recommended for diagnosing PB-type leprosy due to its low sensitivity. 5 Histopathological testing, which is carried out by performing skin biopsy, is currently the gold standard diagnostic test for leprosy.5 However, the test has several limitations because it is invasive and impractical.…”

“…3,11 Therefore, this molecular-based assay can be used to confirm diagnosis. 4,12 Based on the data, this study was aimed to identify the proportion of positive results from TaqMan® probe-based RT-PCR assay compared to histopathological examinations in PB leprosy patients with negative AFB smears. Moreover, this study would also identify the proportion of positive results from TaqMan® probe-based RT-PCR assay using skin scraping and skin biopsy specimens.…”

Caracterização da resposta imune in situ nas lesões de hanseníase indeterminada

“…reação de Mitsuda foi incorporada aos critérios de classificação da hanseníase no ano de 1953, no Sexto Congresso Internacional de Madri, como auxílio na classificação da forma clínica da doença. Ficou deliberado que a reação positiva seria associada a pacientes tuberculoides, e negativa a pacientes virchowianos1,46 . Em pacientes dimorfos a positividade da reação diminui gradativamente perto do polo Virchowiano e aumenta progressivamente à medida que se aproxima o polo tuberculoide46 .…”

“…Ficou deliberado que a reação positiva seria associada a pacientes tuberculoides, e negativa a pacientes virchowianos1,46 . Em pacientes dimorfos a positividade da reação diminui gradativamente perto do polo Virchowiano e aumenta progressivamente à medida que se aproxima o polo tuberculoide46 . Quando negativa, há opiniões controversas: de que não tem valor preditivo para definir o polo de evolução 37 e de que esses casos sempre evoluem para formas bacilíferas 1 .Na forma tuberculoide observam-se lesões granulomatosas tuberculoides organizadas, caracterizadas por histiócitos epitelioides e células gigantes multinucleadas tipo Langhans, rodeadas por linfócitos T CD4 e CD8.…”