Leptospiral agglutinins in pigs slaughtered for consumption and their association with hepatic and pulmonary impairment

Abstract

Leptospiroses are cosmopolitan zoonosis caused by spirochetes of the genus
Leptospira. Over the past years, pigs have been implicated as reservoirs. This study
aimed to investigate anti-Leptospira spp. agglutinins in pig and the association of
lung and liver lesions in seropositive animals. We examined sera from 150 pigs by
microscopic agglutination test (MAT). Out of these, only seven were seropositive
to one or more Leptospira spp. serovar. Fragments of lung and liver of seropositive
animals and of the same number of seronegative animals were submitted for
histopathological evaluation and stained with hematoxylin-eosin (HE) and
immunoperoxidase technique (IPX). In the lungs, there was a significant difference
in the inflammatory infiltrate between seropositive and seronegative animals, but no differences were detected between lung lobes. Liver lesions were more discrete,
however, there was a significant difference between seropositive and seronegative
animals. Immunohistochemistry detected antigen of Leptospira spp. in lung and
liver tissues in both seropositive and seronegative animals. In the lungs, the antigen
was located in phagocytic cells of the interalveolar septum, vascular endothelium,
and alveolar epithelium. At the liver, antigen was present in hepatocytes and vascular endothelial and Kupffer cells. The results indicate that pigs slaughtered for human consumption in the Brazilian cities of Teresina (Piaui State) and Timon (Maranhao State) are infected with Leptospira spp. suggesting that these animals may be a source of infection for humans.