Comparison of the sensitivity of imprint and scraping techniques in the diagnosis of American tegumentary leishmaniasis in a referral centre in Rio de Janeiro, Brazil

Abstract

American tegumentary leishmaniasis (ATL) is an infectious disease that presents a wide spectrum of clinical manifestations making parasitological tests important for its diagnosis. Direct examination, although considered of low sensitivity is still employed mainly in areas with poor laboratory infrastructure. The aim of this study was to standardize the method of collecting and reading the scraping procedure and to then compare sensitivity of this procedure on two sites of the lesion (outer edge-OE and inner edge-IE) and of the imprint against the reference method (isolation in culture) in a group of 110 patients treated at a Referral Center in Rio de Janeiro, Brazil. ATL diagnosis was confirmed in 40 patients (36.4%), 39 cases were caused by L. braziliensis and 1 by L. amazonensis. Imprint was positive in 28 patients and scraping in OE in 17 and in IE in 25 patients, resulting in sensitivity of 70%, 42.5%, and 62.5% respectively. When the three direct examinations were combined, sensitivity value attained 77.5%. Aspects related to ease and quality of the collected material, pain intensity and frequency of bleeding in the scraping procedure were also broached and discussed in this study. The parameters of accuracy presented indicate that the direct methods can be safely used in ATL diagnosis, principally in IE scraping, as it is easy to produce and the examination is not costly, which allows the procedure to be repeated at different moments which, in turn, increases the possibility of finding the parasite. Despite that the direct methods are technically widespread, they are not standardized and the parameters of accuracy are unknown. If we consider the high incidence of leishmaniasis in low-income areas, the implantation of standardized and selective methods would provide advances in the diagnosis of leishmaniasis.