Effectiveness of an immunohistochemical protocol for Leishmania detection in different clinical forms of American tegumentary leishmaniasis

- The immunohistochemical protocol (IHC) is an alternative method for Leishmania diagnosis.
- IHC method was applied on a national scale in Brazil comprising 78 patients.
- IHC method was effective in detecting parasites even in patients with negative MST tests.
- IHC method was effective in detecting different Leishmania species causing ATL.

American tegumentary leishmaniasis (ATL) is a neglected disease widely distributed in Latin America. In Brazil, it is caused by different Leishmania species belonging to the Subgenera Viannia and Leishmania. ATL diagnosis is routinely based on clinical, epidemiological, parasitological and immunological (delayed-type hypersensitivity skin test-DTH) evidences. The main objective of this work was to determine the efficacy of a previous immunohistochemical (IHC) method developed by our group. Seventy eight skin biopsies from patients with different ATL clinical forms and origins were evaluated. The method was previously standardized in ATL patients from the municipality of Caratinga, Minas Gerais, Brazil, all infected with Leishmania (V.) braziliensis. Here, it is evaluated in patients from the North, Southeast and Midwest regions of Brazil. Clinical, parasitological (biopsy PCR) and immunological (Montenegro skin test-MST) diagnosis were performed prior to IHC procedure. The IHC procedure detected 70.5% of the cases having a high agreement with MST diagnosis (kappa = 0.84). A distinguished contribution of this work is that IHC succeed in diagnosing some negative DTH patients. Those were infected with Leishmania (L.) amazonensis, commonly causing the anergic form of the disease. In conclusion, IHC succeed in detecting ATL caused by different Leishmania species from various geographic regions and clinical status. Although it was not able to detect ATL in all patients, it was better than MST providing an additional tool for the diagnosis of ATL patients. There was no significant correlation between clinical forms and histological features including the presence of necrosis.

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