Leptospirosis in slaughtered cows in the Triangulo Mineiro, Minas Gerais: prevalence, serological profile and renal lesions

Abstract

Leptospirosis is a zoonosis that affects several species of domestic and wild animals and is an important cause of economic losses in cattle in Brazil. In this study, we determined the prevalence of bovine leptospirosis in the Triângulo Mineiro region, Minas Gerais, Brazil, identified the most frequent serovars of Leptospira interrogans, and examine the renal pathological changes associated with the disease. Samples of blood serum and kidney fragments from 100 bovine females were collected in cattle abattoir. In the serological investigation 48% of the cows were positive. The serovars for which there were more reactive animals were Wolffi (24%), Hardjo (21%) and Hebdomadis (18%). Among the positive samples, 14/48 showed antibody titers greater than 1:100, and 70.83% of the seropositive animals responded to more than one Leptospira interrogans serovar. Only one farm did not have seropositive cows and in nine farms studied, six (66.66%) presented seropositive animals to the Hebdomadis serovar. At the histopathological examination, the most frequent microscopic lesions in positive animals were hyalinization (81.25%), congestion (81.25%) and hydropic degeneration (70.83%). However, these histopathological alterations were also found in kidneys of animals negative to serology, such as hyalinization (80.77%), congestion (48.07%) and hydropic degeneration (55.77%) and these findings are unrelated to positivity. Histopathological examination of the kidneys is not indicated to replace the serological diagnosis of leptospirosis, and may be used only as a complementary examination. Despite the low frequency of seropositive animals in the Triângulo Mineiro region, the disease is present in a large number of farms. Noteworthy is the high frequency of serovar Hebdomadis and it can be considered an emerging serovar in the region. The evaluation of the frequency of this serovar in other regions becomes important, and once verified should result in the recommendation of the inclusion of this serovar in the leptospirosis control.

A Systematic Review of the geographic distribution of pathogenic Leptospira serovars in the Americas, 1930-2017

“…The predominant serovar was Bratislava, followed by Icterohaemorrhagiae andHardjo (Dewes et al 2020, Otaka et al 2012). This data deviated from what is normally observed in literature, which reports that the serovar Hardjo has specificity for bovine reservoirs (Magalhães et al 2020). Nonetheless, the serovar Hardjo is the one of the most frequently found serovar in domestic animal, and it is responsible for several health problems such as infertility, premature calves, miscarriages and mastitis (Loureiro & Lilenbaum 2020, Mineiro et al 2007.…”

Exposure of Free-Ranging Wild Animals to Zoonotic Leptospira interrogans Sensu Stricto in Slovenia

“…The bacterium requires special growth media, and incubation can last for months [ 44 ]. Histopathological examination of the kidneys is not indicated to replace the serological diagnosis of leptospirosis, and may be used only as a complementary examination [ 45 ]. In the early stages of the disease, the only sensitive and specific test is PCR.…”

Development and standardization of the Dot Blot test for serological diagnosis of bovine leptospirosis

“…definitive serological test. Magalhães et al (2020), determined the prevalence of bovine leptospirosis in the Triângulo Mineiro region, Minas Gerais, Brazil, identified 48% of the cows were reagents for the Wolffi, Hardjo and Hebdomadis serovars in a large number of rural properties.…”