A serologic survey for four zoonotic diseases in coyotes (Canis latrans) in selected areas of Texas : a dissertation

Abstract

The prevalence of Brucella abortus, Trypansoma cruzi, Rickettsia rickettsii, and rabies virus serum antibodies in wild-trapped coyotes (Canis latrans) from various areas of southeastern and southern Texas were determined. The buffered Brucella antigen (card), rivanol precipitation, standard agglutination tube, and cold complement fixation tube tests were utilized to detect B. abortus serum antibodies. Of 117 coyotes collected from 12 counties 23.9% (28) from 8 counties had some reactivity to these tests. Fifteen percent (17) had significant levels (positive by two or more tests) of serum antibodies to B. abortus. No appreciable change in antibody titer was observed during 100+ days in two serologically positive coyotes. Brucella abortus was isolated from various tissues from 18.6% (8/43) of the coyotes. Vertical transmission from a naturally infected female coyote to three pups was detected. An attempt to experimentally infect 4 serologically negative coyotes by conjunctival inoculation with B. abotus biotype 2 was unsuccessful. The rapid fluorescent focus inhibition test (RFFIT) which was utilized to detect rabies virus antibodies in 70 sera from coyotes collected from 6 counties determined that 10% (7) were positive. The positive sera were from coyotes collected in three of the counties. The latex agglutination and direct agglutination tests were used to determine the prevalence of T. cruzi serum antibodies in coyotes collected from 6 counties. Four percent (3/72) were serologically positive as indicated by the latex agglutination tests. Eleven percent (8/72) were serologically positive at a serum dilution>??1:128 as deterimined by the direct agglutination method. The seropositive coyotes were collected from three of the counties. The prevalence of R. rickettsii serum antibodies in coyotes collected from 9 counties was 5.4% (4/74) by the complement fixation micotiter technique. The serologically positive coyotes were collected from three counties.