Aspectos Histopatológicos da Leishmaniose Cutânea e Visceral em pele e rim de gatos domésticos naturalmente infectados

Abstract

Leishmaniases are zoonoses caused by protozoa of the genus Leishmania, with significant impact on public health. The disease can occur in tegumentary or visceral form, depending on the Leishmania species, and transmission is through the bite of female sandflies of the family Psychodidae, commonly known as phlebotomine sandflies. In the Americas, Brazil concentrates the majority of reported cases of both forms. Domestic and wild felines are hosts of the protozoa species that are most incident in Brazil, with reports of infected cats mainly in areas of intense disease transmission. Despite being considered more resistant, infected felines may present cutaneous alterations in tegumentary leishmaniasis and alterations in different organs such as skin, liver, spleen, lymph nodes, and lungs in visceral leishmaniasis. Histopathological analysis is a diagnostic method that can aid in understanding the damage caused to the host, and few histopathological studies have been conducted in naturally parasitized domestic felines to date. This study aimed to evaluate the application of different staining methods in the analysis of cutaneous tissue of naturally parasitized domestic felines by Leishmania amazonensis and report the renal alterations caused by Leishmania infantum infection in cats. For the analyses, samples of cutaneous nodules from a cat positive for L. amazonensis were collected and subjected to histological processing, followed by staining with hematoxylin-eosin (HE), periodic acid-Schiff (PAS), Fontana-Masson, fast green, and Mallory's trichrome, and the staining quality was evaluated. Samples of kidneys from 5 cats positive for L. infantum and 5 negative cats were stained with HE and PAS and were analyzed and compared. Among the stains analyzed in cutaneous nodular tissue, hematoxylin and eosin staining showed better performance for visualizing the protozoa and tissue components. The other stains, although not yielding the same result as hematoxylin and eosin, still managed to reveal the parasite in the tissue, albeit more difficultly. Renal alterations were observed in 100% of positive and negative cats. The most frequent glomerular alteration was membranous glomerulonephritis, present in all negative animals and 80% of positive animals, but with different intensity grades (P<0.05). Positive animals for Leishmania presented interstitial nephritis, which was not found in negative cats (P<0.05). The results obtained show that hematoxylin and eosin staining was the best staining method for visualizing Leishmania and skin tissue aspects. Additionally, it was evidenced that cats also develop visceral lesions of leishmaniasis, as demonstrated in this study by the significant occurrence of renal lesions.