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Visceral leishmaniasis is a zoonosis in which the dog appears as the main source of infection in urban areas. Its diagnosis is complex and the cytopathological exam is a fast and cheap alternative to parasite direct visualization and its sensitivity can be increased by immunocytochemistry, though with a higher cost. The accuracy of such methods is dependent on the microscopist's experience and therefore, this study evaluated the reliability of such techniques between two observers, from bone marrow aspirates of 50 dogs from an endemic area for the disease. The parasitological culture in Novy-MacNeal-Nicolle medium was used as the reference standard. Among the main findings, the sensitivities obtained by observers I and II were respectively 62.5% and 37.5%, while specificities were 81.1% and 100%. On immunocytochemistry evaluation, the sensitivity was 0% for both evaluators and the specificity 97.3% and 100%. The agreement between evaluators was weak (κ = 0.167) for the cytopathological test and it could not be evaluated for immunocytochemistry, for which there was no detection by the evaluator II. The agreements among the diagnostic methods and the standard reference for the observer I were reasonable (κ = 0.364) for cytopathological examination and bad (κ = -0.041) for immunocytochemistry. For observer II, such agreement could be assessed only for the cytopathological test, being moderate (κ = 0.497). The results point to the possible expertise difference between evaluators, with the evaluator II demonstrating greater experience when interpreting the citopathological test. Although there was the expected sensitivity increase with immunocytochemistry, the technique used in this study was not effective for the diagnosis of infection, regardless of the evaluator. [ABSTRACT FROM AUTHOR]

Parasitological methods are the most specific procedures used for the diagnosis of Leishmania spp. infection, but their limited sensitivity poses a disadvantage and prompts the need for alternatives. The choice of site for sample collection influences diagnostic sensitivity. The combination of an accurate diagnostic method and a technique that allows large-scale field studies is highly desirable to enhance the investigation of Leishmania spp. infection in dogs, especially in endemic regions. The bone marrow is a good target for the detection of Leishmania spp. in dogs. In this context, bone marrow aspiration is rapid and less invasive compared with biopsy procedures, and also enables cell block processing, paraffin wax embedding and the sectioning of samples for further histological and immunohistochemical analyses. The aim of this study was to describe for the first time parasitological methods (immunohistochemistry [IHC] and histopathology) using the cell block technique with bone marrow aspirates for the diagnosis of Leishmania spp. infection in dogs. Bone marrow aspiration was performed in 45 dogs from an area endemic for visceral leishmaniosis for parasitological culture and the cell block technique (histopathology and IHC). Fourteen (31.1%) dogs tested positive for Leishmania spp. by IHC, six (13.3%) by parasitological culture and four (8.9%) by histopathology. Cell block IHC was a useful tool for the diagnosis of canine visceral leishmaniosis. Further studies should be conducted to validate this method for routine epidemiological screening., (Copyright © 2016 Elsevier Ltd. All rights reserved.)