Evaluation of different diagnostic methods of American Cutaneous Leishmaniasis in the Brazilian Amazon

Abstract

Epidemiological studies have been conducted to better understand the dynamics of American Cutaneous Leishmaniasis (ACL) in the Amazon region where distinct species of Leishmania circulate. In endemic areas, the optimal diagnosis must be made in the earlier clinical presentation to avoid the complications of chronic disease. The scarcity of financial support, laboratory infrastructure and trained persons are the major obstacles in this reality. This paper describes the result of performing different diagnostic methods for ACL in Amazonas State between the years 2010 and 2011. The tests used were the intradermal skin test (Montenegro's skin test), ELISA (Enzyme-Linked Immunosorbent Assay), direct examination, culture isolation and identification of Leishmania species. A total of 38 suspected human cases of ACL were diagnosed by different methods, of which 71.0% (n = 27) were positive by direct examination, 75.6% (n = 28) had positivity in the culture isolates and, of these, 54.0% (n = 19) had infection with Leishmania (Viannia) guyanensis. The positivity of the intradermal skin test with the leishmanin solution was observed in 77.0% of cases analyzed and the serology with detection of IgG and IgM showed the presence of antibodies in 100% of exams realized results, showing variation in the titles of antibodies. The success of Leishmaniasis treatment depends on an effective and early diagnosis. Parasitological diagnosis is highly specific, but sensitivity is subject to variation because the tissue distribution of parasites generally is not homogeneous and depends on the specie of parasite. Moreover, parasitological tests require invasive procedures and depend on restrictive conditions for the collection of biological sample, which limit their use in large-scale for epidemiological studies. ELISA has been the most widely used serological method for the diagnosis of Visceral Leishmaniasis (VL) as it is easy to perform and has a low cost. However, flaws in specificity are observed in the diagnosis of cutaneous leishmaniasis. Actually the diagnosis needs to be done as an associated methods depending on the question to be solved.