Diagnostic Characterization of a Feral Swine Herd Enzootically Infected with Brucella

• Published in: Journal of veterinary diagnostic investigation 2007-05, Vol.19 (3), p.227-237
• Main Authors: Stoffregen, W.C, Olsen, S.C, Wheeler, C.J, Bricker, B.J, Palmer, M.V, Jensen, A.E, Halling, S.M, Alt, D.P
• Format: Article
• Language: English
• Subjects: Agglutination Tests - veterinary; Animals; Animals, Wild; Antibodies, Bacterial - blood; Brucella - genetics; Brucella - isolation & purification; Brucella melitensis biovar Abortus; Brucella melitensis biovar Suis; brucellosis; Brucellosis - blood; Brucellosis - epidemiology; Brucellosis - pathology; Brucellosis - veterinary; disease diagnosis; disease transmission; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Female; females; feral animals; Fluorescence Polarization Immunoassay - veterinary; gender differences; Histocytochemistry - veterinary; Male; males; Minisatellite Repeats - genetics; molecular sequence data; nucleotide sequences; Polymerase Chain Reaction - veterinary; Sequence Analysis, DNA; Seroepidemiologic Studies; seroprevalence; South Carolina - epidemiology; Swine; swine diseases; Swine Diseases - blood; Swine Diseases - epidemiology; Swine Diseases - microbiology; Swine Diseases - pathology; trapping; Zoonoses - microbiology
• ISSN: 1040-6387; 1943-4936
• DOI: 10.1177/104063870701900301

Correspondence: 1 Corresponding Author: William C Stoffregen, DVM, National Animal Disease Center, 2300 Dayton Avenue, Ames, IA 50010, e-mail: bstoffre{at}nadc.ars.usda.gov Eighty feral swine were trapped from a herd that had been documented to be seropositive for Brucella and which had been used for Brucella abortus RB51 vaccine trials on a 7,100-hectare tract of land in South Carolina. The animals were euthanized and complete necropsies were performed. Samples were taken for histopathology, Brucella culture, and Brucella serology. Brucella was cultured from 62 (77.5%) animals. Brucella suis was isolated from 55 animals (68.8%), and all isolates were biovar 1. Brucella abortus was isolated from 28 animals (35.0%), and isolates included field strain biovar 1 (21 animals; 26.3%), vaccine strain Brucella abortus S19 (8 animals, 10.0%), and vaccine strain Brucella abortus RB51 (6 animals, 7.5%). Males were significantly more likely to be culture positive than females (92.9% vs. 60.6%). Thirty-nine animals (48.8%) were seropositive. Males also had a significantly higher seropositivity rate than females (61.9% vs. 34.2%). The relative sensitivity rates were significantly higher for the standard tube test (44.6%) and fluorescence polarization assay (42.6%) than the card agglutination test (13.1%). Lesions consistent with Brucella infection were commonly found in the animals surveyed and included inflammatory lesions of the lymph nodes, liver, kidney, and male reproductive organs, which ranged from lymphoplasmacytic to pyogranulomatous with necrosis. This is the first report of an apparent enzootic Brucella abortus infection in a feral swine herd suggesting that feral swine may serve as a reservoir of infection for Brucella abortus as well as Brucella suis for domestic livestock. Key Words: Brucella abortus • Brucella suis • brucellosis • feral swine • swine brucellosis