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Prevalence of Pseudorabies and Brucellosis in Feral Swine from Coastal Bend and Southwest Texas Counties

Brandon J. Dominguez, D. Bruce Lawhorn DVM MS, Thomas L Lester DVM PhD, Loyd W Sneed PhD

From the Department of Large Animal Medicine and Surgery, Extension Veterinary Medicine (Lawhorn), College of Veterinary Medicine (Dominguez), Texas A&M University, College Station, TX 77843; and Texas Veterinary Medical Diagnostic Lab (Lester, Sneed), 1 Sippel Road, College Station, TX 77843

Objective: To determine the prevalence of pseudorabies and brucellosis in Texas feral swine.

Animals: Hunter killed feral hogs harvested between January 2001 and February 2002 in the Coastal Bend and Southwest Texas counties were used to obtain tonsil samples in both years and meat juice and/or serum in 2002.

Procedure: Tonsil samples were tested for the presence of pseudorabies virus by the fluorescent antibody tissue section test (FA) and virus isolation (VI);  polymerase chain reaction (PCR) was used to test tonsils for the presence of pseudorabies viral DNA.  ELISA and latex agglutination (LA) were used to screen meat juice and/or serum for antibodies to pseudorabies virus; serum virus neutralization (SN) was used as a confirmatory test on positive ELISA and/or LA results. The brucellosis card test and the particle concentration fluorescence immunoassay test (PCFIA) were used as screening and confirmatory tests, respectively, for Brucella antibodies. 

Results: FA and VI tests were negative for all tonsils (145) collected in both years. PCR tests were negative for all tonsils (85) in 2002 and 38/60 tonsils collected in 2001. Sample quantity was insufficient to run PCR on 22/60 tonsil samples. PCR results from the University of Illinois on all 145 tonsil samples are pending.  Although 66%, 23.5% and 10.5% of meat juice samples were not testable, positive and negative, respectively, by ELISA and 66% of meat juice and/or sera were positive by LA, SN tests confirmed only two seropositives and two suspicious results. Despite 94% and 6% of meat juice samples being not testable and negative by the brucellosis card test, 82% of the samples were testable by PCFIA and were seronegative.

Conclusion and Clinical Significance:  Decreasing prevalence of pseudorabies and brucellosis in the feral hog population may indicate lowered risk for transmission to domestic swine and allow for Texas to more easily reach free status in the domestic swine eradication programs for these two diseases.