Patho-epidemiological and molecular diagnosis of swine brucellosis in Punjab

Abstract

Brucellosis is one of the major reproductive tract diseases of swine and causes a huge economic loss to pig farmers. In this study, serological, gross pathological, histopathological, immunohistochemical and Polymerase Chain Reaction technique(s) have been applied for diagnosis of brucellosis in pig. Seroprevalence studies showed prevalence of brucellosis to be 16.7% by Rose Bengal Plate Test (RBPT) and 12.5% by competitive ELISA(c-ELISA). In this study, comparison was done between RBPT and c-ELISA for serological diagnosis of brucellosis which revealed substantial degree of agreement (Kappa= 0.676, 95% CI= 0.372-0.826) between two tests. Histopathological examination revealed focal to diffuse mixed infiltration of neutrophils or lymphocytesin the fetal organs like lung especially in bronchi and interstitial septa. Lesions in the placenta were characterized by diffuse lympho-mononuclear cell infiltration. Histopathological changes in female reproductive tracts were characterized by cellular infiltration of the endometrial stroma, endometrial glands and hyperplasia of periglandular connective tissue. Immunohistochemical (IHC) staining revealed intracytoplasmic immunostaining of Brucella in bronchial epithelial cells of lung, endothelial cells in spleen, hepatocytes of liver, cells within the lymph node, kidney of fetus and placenta. In addition, positive immunostaining to Brucella was also seen in lamina propria cells of uterus. By PCR, eight out of 34 samples (2 from stomach contents, 2 from placental cotyledons and 4 from pooled tissue(s) produced 193 bpsized ampliconspecific for Brucella genus. In the present study, PCR and IHC provide a reliable test for the diagnosis of brucellosis in abortion cases on aborted fetal tissue and placental cotyledons. However, serology is important for detection of Brucella positive animal in a farm .