Brucella Abortus in Captive Bison. I. Serology, Bacteriology, Pathogenesis, and Transmission to Cattle

Abstract

Two groups of six, non-brucellosis vaccinated, brucellosis seronegative pregnant American bison (Bison bison) were individually challenged with 1 x 10(7) colony forming units (CFU) of Brucella abortus strain 2308. Three days after challenge, each bison group was placed in a common paddock with six non-vaccinated, brucellosis susceptible, pregnant domestic heifers. In a parallel study, two groups of six susceptible, pregnant cattle were simultaneously challenged with the identical dose as the bison and each group was placed with six susceptible cattle in order to compare bison to cattle transmission to that observed in cattle to cattle transmission. Blood samples were collected from bison and cattle weekly for at least 1 mo prior to exposure to B. abortus and for 180 days post-exposure (PE). Sera from the bison and cattle were evaluated by the Card, rivanol precipitation, standard plate agglutination, standard tube agglutination, cold complement fixation tube, warm complement fixation tube, buffered acidified plate antigen, rapid screening, bovine conjugated enzyme linked immunosorbent assay, bison or bovine conjugated enzyme linked immunosorbent assay, and the hemolysis-in-gel techniques for the presence of antibodies to Brucella spp. At the termination of pregnancy by abortion or birth of a live-calf, quarter milk samples, vaginal swabs, and placenta were collected from the dam. Rectal swabs were collected from live calves, and mediastinal lymph nodes, abomasal contents and lung were taken at necropsy from aborted fetuses for culture of Brucella spp. These tissues and swabs were cultured on restrictive media for the isolation and identification of Brucella spp. Pathogenesis of brucellosis in bison was studied in an additional group of six pregnant bison which were challenged with 1 x 10(7) CFU of B. abortus strain 2308. One animal was euthanatized each week PE. Tissues were collected at necropsy and later examined bacteriologically and histologically. Lesions of brucellosis in bison did not significantly differ grossly or histologically from those in cattle. There were six abortions and two nonviable calves in the bison group, as compared to nine abortions in the 12 similarly inoculated cattle. As determined by bacterial isolations, transmission of B. abortus from bison to cattle (five of 12 susceptible cattle became infected) did not differ statistically from cattle to cattle transmission (six of 12 susceptible cattle became infected) under identical conditions. No single serologic test was constantly reliable to diagnosing B. abortus infected bison for 8 wk PE.(ABSTRACT TRUNCATED AT 400 WORDS)

Pathology of Brucellosis in Bison From Yellowstone National Park

“…Lesions and bacteriologic findings in the Brucella spp.-positive aborted fetuses and placentas are similar to those in experimental infections of B. abortus in bison (Davis et al, 1990) and cattle (Payne, 1959), and are consistent with the laboratory results in the previously reported brucellosis abortion in a YNP bison (Rhyan et al, 1994). The lesions and bacteriologic findings in the 2-wk-old calf indicate multiorgan involvement with likely septicemia.…”

“…105) was similar to the findings of Williams et al (1993), and to results of experimental infections in bison (Davis et al, 1990) and cattle (Payne, 1959). The presence of large numbers of brucellae in the ileum and rectum probably resulted from ingestion of portions of the infected placenta or licking the aborted fetus.…”

“…Since the lymphatics of the mammary gland drain to the supramammary lymph nodes, and since only portions of each mammary gland were collected and cultured, it is likely the high rate of supramammary lymph node infection in the bison is indicative of an actual higher rate of mammary gland infection than is reflected by these results. Two experimental infection studies in pregnant bison have demonstrated B. abortus present in mammary gland following abortion or calving (Davis et al, 1990;Bevins et al, 1996). Nevertheless, the discrepencies in demonstrable mammary gland and uterine infection rates between the cattle and bison in this study suggest that some species-related differences in sites of tissue localization of B. abortus in chronically-infected animals may occur.…”

“…Subsequently, the disease was found in bison from the National Bison Range in Moiese (Montana, USA) (Creech, 1930), Elk Island National Park (Alberta, Canada) (Corner and Connell, 1958), Wood Buffalo National Park (Canada) (Choquette et al, 1978), Teton County (Wyoming, USA) (Williams et al, 1993), and private herds in the USA (Flagg, 1983;Rhyan et al, 1997b). Abortions or retained placentas in bison from brucellosis infected herds have been reported (Creech, 1930;Corner and Connell, 1958), and have been observed in experimental infections (Davis et al, 1990(Davis et al, , 1991; however, only two naturally-occurring abortions with laboratory confirmation of B. abortus as the causative agent have been reported (Williams et al, 1993;Rhyan et al, 1994). Little additional information is published on the pathogenesis of B. abortus infection in female bison, and some investigators have speculated that the disease in YNP bison is markedly different from that in cattle (Meyer and Meagher, 1995).…”

Validation of the Fluorescence Polarization Assay and Comparison to Other Serological Assays for the Detection of Serum Antibodies to Brucella Abortus in Bison

“…They were never subjected to the same scrutiny for validation as present day primary binding assays. As well, the data reported in the literature (Thorne et al, 1978;Davis et al, 1990;Nicoletti, 1992) suggests that no single test could be relied upon to definitively diagnose brucellosis in bison.…”