Pathogenesis and pathobiology of brucellosis in wildlife.

Natural infections by Brucella spp. have been observed in wild populations. Owing to the similarity of lesions and the course of disease across host and pathogen species, the pathogenesis of brucellosis in wildlife is considered similar to that in domestic animals, which has been studied extensively. Similarities include tropism for reproductive and mammary tissues, trophoblast colonisation by the organism, and similar histopathological findings in organs, especially in the reproductive tract. Differences in the disease course exist and are likely to be attributable to immunological and behavioural differences among species. Further study of the pathogenesis and pathobiology of brucellosis in wildlife is expected to yield unique knowledge with application to disease management in both wild and domestic species.

The pathogenesis of foot-and-mouth disease II: viral pathways in swine, small ruminants, and wildlife; myotropism, chronic syndromes, and molecular virus-host interactions.

Investigation into the pathogenesis of foot-and-mouth disease (FMD) has focused on the study of the disease in cattle with less emphasis on pigs, small ruminants and wildlife. 'Atypical' FMD-associated syndromes such as myocarditis, reproductive losses and chronic heat intolerance have also received little attention. Yet, all of these manifestations of FMD are reflections of distinct pathogenesis events. For example, naturally occurring porcinophilic strains and unique virus-host combinations that result in high-mortality outbreaks surely have their basis in molecular-, cellular- and tissue-level interactions between host and virus (i.e. pathogenesis). The goal of this review is to emphasize how the less commonly studied FMD syndromes and host species contribute to the overall understanding of pathogenesis and how extensive in vitro studies have contributed to our understanding of disease processes in live animals.

Emergence of diseases from wildlife reservoirs.

Interest in the epidemiology of emerging diseases of humans and livestock as they relate to wildlife has increased greatly over the past several decades. Many factors, most anthropogenic, have facilitated the emergence of diseases from wildlife. Some livestock diseases have "spilled over" to wildlife and then "spilled back" to livestock. When a population is exposed to an infectious agent, depending on an interaction of factors involving the host, agent, and environment, the population may be resistant to infection or may become a dead-end host, a spillover host, or a maintenance host. Each exposure is unique; the same species of host and agent may respond differently in different situations. Management actions that affect the environment and behavior of a potential host animal may allow the emergence of a new or as yet undetected disease. There are many barriers in preventing, detecting, monitoring and managing wildlife diseases. These may include political and legal hurdles, lack of knowledge about many diseases of wildlife, the absence of basic data on wildlife populations, difficulties with surveillance, and logistical constraints. Increasing interaction between wildlife and humans or domestic animals may lead to disease emergence and require innovative methods and strategies for disease surveillance and management in wildlife.

Humoral immune responses of white-tailed deer (Odocoileus virginianus) to Mycobacterium bovis BCG vaccination and experimental challenge with M. bovis.

Monitoring of the kinetics of production of serum antibodies to multiple mycobacterial antigens can be useful as a diagnostic tool for the detection of Mycobacterium bovis infection as well as for the characterization of disease progression and the efficacy of intervention strategies in several species. The humoral immune responses to multiple M. bovis antigens by white-tailed deer vaccinated with BCG orally via a lipid-formulated bait (n=5), orally in liquid form (n=5), and subcutaneously (n=6) were evaluated over time after vaccination and after experimental challenge with virulent M. bovis and were compared to the responses by unvaccinated deer (n=6). Antibody responses were evaluated by using a rapid test (RT), a multiantigen print immunoassay (MAPIA), a lipoarabinomannan enzyme-linked immunosorbent assay (LAM-ELISA), and immunoblotting to whole-cell sonicate and recombinant antigen MPB83. MAPIA and RT detected minimal to no antibody responses over those at the baseline to multiple M. bovis antigens in vaccinated white-tailed deer after challenge. This was in contrast to the presence of more readily detectable antibody responses in nonvaccinated deer with more advanced disease. The LAM-ELISA results indicated an overall decrease in the level of production of detectable antibodies against lipoarabinomannan-enriched mycobacterial antigen in vaccinated animals compared to that in nonvaccinated animals after challenge. Immunoblot data were inconsistent but did suggest the occurrence of unique antibody responses by certain vaccinated groups to Ag85 and HSP70. These findings support further research toward the improvement and potential use of antibody-based assays, such as MAPIA, RT, and LAM-ELISA, as tools for the antemortem assessment of disease progression in white-tailed deer in both experimental and field vaccine trials.

Efficacy of oral and parenteral routes of Mycobacterium bovis bacille Calmette-Guerin vaccination against experimental bovine tuberculosis in white-tailed deer (Odocoileus virginianus): a feasibility study.

We investigated the efficacy of oral and parenteral Mycobacterium bovis bacille Calmette-Guerin Danish strain 1331 (BCG) in its ability to protect white-tailed deer (Odocoileus virginianus) against disease caused by M. bovis infection. Twenty-two white-tailed deer were divided into four groups. One group (n=5) received 10(9) colony-forming units (cfu) BCG via a lipid-formulated oral bait; one group (n=5) received 10(9) cfu BCG in culture directly to the oropharynx, one group (n=6) was vaccinated with 10(6) cfu BCG subcutaneously, and one group served as a control and received culture media directly to the oropharynx (n=6). All animals were challenged 3 mo after vaccination. Five months postchallenge the animals were examined for lesions. Results indicate that both oral forms of BCG and parenterally administered BCG offered significant protection against M. bovis challenge as compared to controls. This study suggests that oral BCG vaccination may be a feasible means of controlling bovine tuberculosis in wild white-tailed deer populations.

Immunocontraception of Florida feral swine with a single-dose GnRH vaccine.

PROBLEM: Methods to limit fertility of feral swine are needed to reduce transmission of diseases and agricultural and ecosystem damage. Method of Study We evaluated a single-shot GnRH immunocontraceptive vaccine in both male and female feral swine for its effect on fertility and functional status of the reproductive tissues. Captive feral pigs were randomly assigned to receive 1000 or 2000 microg GnRH-KLH vaccine treatments or no treatment. RESULTS: After 36 weeks, none of the 2000-microg-treated females and only 20% of the 1000-microg-treated females were pregnant. This corresponded to reduced serum progesterone, regressed tissues within the reproductive tract and lack of evidence for follicular development leading to ovulation. Males were less responsive to the vaccine than females, but more responsive to the lower dose of the vaccine than the higher dose. CONCLUSIONS: The single-shot GnRH vaccine is effective in controlling fertility of female feral swine and may be useful for population reduction.

Uterine mast cells and immunoglobulin-E antibody responses during clearance of Tritrichomonas foetus.

We showed earlier that Tritrichomonas foetus-specific bovine immunoglobulin (Ig)G1 and IgA antibodies in uterine and vaginal secretions are correlated with clearance of this sexually transmitted infection. Eosinophils have been noted in previous studies of bovine trichomoniasis but the role of mast cells and IgE responses have not been reported. The hypothesis that IgE and mast cell degranulation play a role in clearance was tested in 25 virgin heifers inseminated experimentally and infected intravaginally with T. foetus strain D1 at estrus and cultured weekly. Groups were euthanatized at 3, 6, 9, or 12 weeks, when tissues were fixed and secretions were collected for culture and antibody analysis. Immunohistochemistry using a monoclonal antibody to a soluble lipophosphoglycan (LPG)-containing surface antigen (TF1.17) demonstrated antigen uptake by uterine epithelial cells. Lymphoid nodules were detected below antigen-positive epithelium. Little IgG2 antibody was detected but IgG1, IgA, IgM, and IgE T. foetus-specific antibodies increased in uterine secretions at weeks 6 and 9 after infection. This was inversely proportional to subepithelial mast cells numbers and most animals cleared the infection by the sampling time after the lowest mast cell count. Furthermore, soluble antigen was found in uterine epithelium above inductive sites (lymphoid nodules). Cross-linking of IgE on mast cells by antigen and perhaps LPG triggering appears to have resulted in degranulation. Released cytokines may account for production of predominantly Th2 (IgG1 and IgE) and IgA antibody responses, which are related to clearance of the infection.

Prevalence of antibodies to Neospora caninum, Sarcocystis neurona, and Toxoplasma gondii in wild horses from central Wyoming.

Sarcocystis neurona, Neospora caninum, N. hughesi, and Toxoplasma gondii are 4 related coccidians considered to be associated with encephalomyelitis in horses. The source of infection for N. hughesi is unknown, whereas opossums, dogs, and cats are the definitive hosts for S. neurona, N. caninum, and T. gondii, respectively. Seroprevalence of these coccidians in 276 wild horses from central Wyoming outside the known range of the opossum (Didelphis virginiana) was determined. Antibodies to T. gondii were found only in 1 of 276 horses tested with the modified agglutination test using 1:25, 1:50, and 1:500 dilutions. Antibodies to N. caninum were found in 86 (31.1%) of the 276 horses tested with the Neospora agglutination test--the titers were 1:25 in 38 horses, 1:50 in 15, 1:100 in 9, 1:200 in 8, 1:400 in 4, 1:800 in 2, 1:1,600 in 2, 1:3,200 in 2, and 1:12,800 in 1. Antibodies to S. neurona were assessed with the serum immunoblot; of 276 horses tested, 18 had antibodies considered specific for S. neurona. Antibodies to S. neurona also were assessed with the S. neurona direct agglutination test (SAT). Thirty-nine of 265 horses tested had SAT antibodies--in titers of 1:50 in 26 horses and 1:100 in 13. The presence of S. neurona antibodies in horses in central Wyoming suggests that either there is cross-reactivity between S. neurona and some other infection or a definitive host other than opossum is the source of infection. In a retrospective study, S. neurona antibodies were not found by immunoblot in the sera of 243 horses from western Canada outside the range of D. virginiana.

Relationships among ecology, demography and diseases of European bison (Bison bonasus).

The bison population in the Bialowieza Forest in Poland has now grown to approximately 300, while the herds in the Belarusian part of the forest total about 240 bison. The first signs of a health problem in these herds appeared in 1980, when two cases of balanoposthitis were detected in two bulls (2 and 5 years of age). Since 1980 research has been conducted to explain the cause of diseases, particularly balanoposthitis, and to monitor the health of bison in Bialowieza Forest. A total number of 614 bison (294 male and 320 female) of different ages was eliminated between 1980 and 2000. Not all the culled bison were examined (postmortem analysis, histopathological, bacteriological, virological and toxicological examinations, serological tests, molecular research). Based on the increase in numbers, reproduction in this population for the past 21 years is generally considered successful. Among 182 male bison eliminated during 1990-2000, only 85, or 47%, of the animals had balanoposthitis. Thus, the percentage of balanoposthitis cases went from 100% during the 1980s down to 47% in the past decade. It appears that the culling process has been a major factor leading to this decrease. It can be assumed that a set of factors is involved in the appearance of the disease (Corynebacterium spp., Bacillus sp., Pseudomonas aeruginosa, Escherichia coli, Ureoplasma spp, Fusobacterium necrophorum, Streptoccocus spp., Staphyloccocus spp.) while opportunistic infections including nematodes (Onchocerca spp.) are responsible for the occurrence of secondary lesions.

Seroconversion and abortion in cattle experimentally infected with Brucella sp. isolated from a Pacific harbor seal (Phoca vitulina richardsi).

Previously unrecognized Brucella species have been isolated from a number of marine mammals, including harbor seals (Phoca vitulina richardsi) in the Puget Sound area of the state of Washington. Because of the presence of dairy herds in proximity to the harbor seal populations, a study was conducted to determine the effects of the harbor seal Brucella isolate in experimentally inoculated cattle. Six pregnant cattle were exposed by intravenous injection (n = 3) or intraconjunctival inoculation (n = 3). Two pregnant cows were intravenously injected with saline and served as controls. All of the cows receiving the Brucella seroconverted on 1 or more tests commonly used for the detection of Brucella abortus infection. Two of the cattle receiving the intravenous inoculation aborted, and brucellae were demonstrated in the fetuses and dams immediately following abortion. The remaining 4 Brucella-inoculated animals and their fetuses were culture negative for the organism at 14 weeks postinoculation. Results of this study indicate the marine mammal Brucella is capable of producing seroconversion and abortion in cattle but is less pathogenic in that species than B. abortus.

Experimental infection of nontarget species of rodents and birds with Brucella abortus strain RB51 vaccine.

The Brucella abortus vaccine strain RB51 (SRB51) is being considered for use in the management of bnucellosis in wild bison (Bison bison) and elk (Cervus elaphus) populations in the Greater Yellowstone Area (USA). Evaluation of the vaccines safety in non-target species was considered necessary prior to field use. Between June 1998 and December 1999, ground squirrels (Spermophilus richardsonii, n = 21), deer mice (Peromyscus maniculatus, n = 14), prairie voles (Microtus ochrogaster, n = 21), and ravens (Corvus corax, n = 13) were orally inoculated with SRB51 or physiologic saline. Oral and rectal swabs and blood samples were collected for bacteriologic evaluation. Rodents were necropsied at 8 to 10 wk and 12 to 21 wk post inoculation (PI), and ravens at 7 and 11 wk PI. Spleen, liver and reproductive tissues were collected for bacteriologic and histopathologic evaluation. No differences in clinical signs, appetite, weight loss or gain, or activity were observed between saline- and SRB51-inoculated animals in all four species. Oral and rectal swabs from all species were negative throughout the study. In tissues obtained from SRB51-inoculated animals, the organism was isolated from six of seven (86%) ground squirrels, one of six (17%) deer mice, none of seven voles, and one of five (20%) ravens necropsied at 8, 8, 10, and 7 wk PI, respectively. Tissues from four of seven (57%) SRB51-inoculated ground squirrels were culture positive for the organism 12 wk PI; SRB51 was not recovered from deer mice, voles. or ravens necropsied 12, 21, or 11 wk, respectively, PI. SRB51 was not recovered from saline-inoculated ground squirrels, deer mice, or voles at any time but was recovered from one saline-inoculated raven at necropsy, 7 wk PI, likely attributable to contact with SRB51-inoculated ravens in an adjacent aviary room. Spleen was time primary tissue site of colonization in ground squirrels, followed by the liver and reproductive organs. The results indicate oral exposure to SRB51 does not produce morbidity or mortality in ravens, ground squirrels, deer mice, or prairie voles.

Pathology of brucellosis in bison from Yellowstone National Park.

Between February 1995 and June 1999, specimens from seven aborted bison (Bison bison) fetuses or stillborn calves and their placentas, two additional placentas, three dead neonates, one 2-wk-old calf, and 35 juvenile and adult female bison from Yellowstone National Park (USA) were submitted for bacteriologic and histopathologic examination. One adult animal with a retained placenta had recently aborted. Serum samples from the 35 juvenile and adult bison were tested for Brucella spp. antibodies. Twenty-six bison, including the cow with the retained placenta, were seropositive, one was suspect, and eight were seronegative. Brucella abortus biovar 1 was isolated from three aborted fetuses and associated placentas, an additional placenta, the 2-wk-old calf, and 11 of the seropositive female bison including the animal that had recently aborted. Brucella abortus biovar 2 was isolated from one additional seropositive adult female bison. Brucella abortus was recovered from numerous tissue sites from the aborted fetuses, placentas and 2-wk-old calf. In the juvenile and adult bison, the organism was more frequently isolated from supramammary (83%), retropharyngeal (67%), and iliac (58%) lymph nodes than from other tissues cultured. Cultures from the seronegative and suspect bison were negative for B. abortus. Lesions in the B. abortus-infected, aborted placentas and fetuses consisted of necropurulent placentitis and mild bronchointerstitial pneumonia. The infected 2-wk-old calf had bronchointerstitial pneumonia, focal splenic infarction, and purulent nephritis. The recently-aborting bison cow had purulent endometritis and necropurulent placentitis. Immunohistochemical staining of tissues from the culture-positive aborted fetuses, placentas, 2-wk-old calf, and recently-aborting cow disclosed large numbers of B. abortus in placental trophoblasts and exudate, and fetal and calf lung. A similar study with the same tissue collection and culture protocol was done using six seropositive cattle from a B. abortus-infected herd in July and August, 1997. Results of the bison and cattle studies were similar.

Experimental Brucella abortus induced abortion in a llama: pathologic effects.

Brucella abortus infection has not been documented in llamas. This report describes the abortion of the only pregnant animal in a group of 12. The llama was infected by inoculating 1 x 10(8) viable B. abortus organisms into the conjunctival sac. Forty-three days postinfection, the llama aborted a fetus of approximately 8 months gestational age. Brucella organisms were isolated from the placenta and all fetal specimens examined. These organisms were also isolated from the dam's mammary gland and numerous lymph nodes when the llama was necropsied 42 days later. Microscopically, there was a moderate, multifocal, lymphocytic and histiocytic, subacute placentitis with marked loss of trophoblastic epithelial cells. The superficial chorioallantoic stroma contained abundant necrotic and mineralized debris as well as numerous swollen capillaries protruding multifocally from the denuded surface. Immunohistochemistry revealed that these capillaries, as well as sloughed and intact trophoblasts, were expanded by large numbers of Brucella organisms. Brucellar antigen was also detected in occasional macrophages in the fetal kidney and lung. Ultrastructurally, bacteria labeled by an antibody-based colloidal gold procedure were located within degenerate capillaries, within necrotic leukocytes, and extracellularly in the placental stroma.

Identification of tuberculosis in cattle slaughtered in Mexico.

OBJECTIVES: To determine epidemiologic factors associated with tuberculosis (TB) in dairy cattle slaughtered in 6 important regions for milk production in Mexico. ANIMALS: 2,500 cattle. PROCEDURE: Tissue specimens with lesions typical of TB were obtained during routine inspection of carcasses at abbatoirs between July 1996 and January 1997. Infection with Mycobacterium organisms was confirmed by histologic examination and bacteriologic culture. Species identification was made by use of selective growth medium, conventional biochemical tests, and radiometric procedures. Epidemiologic information for affected cattle was obtained by personal interviews with cattle dealers and owners. RESULTS: 400 (16%) of 2,500 cattle carcasses had gross lesions typical of TB. Of the 400 infected cattle, 336 (84%) had lesions in > or = 1 lymph node. Infection was confirmed in 87% of cattle with gross lesions by histologic examination, in 77% by bacteriologic culture at a laboratory in the United States, and in 59% by bacteriologic culture at a laboratory in Mexico. Most cattle were adult females in fair to good body condition that came from large herds (> 500 cattle) and were not included in the Mexican TB control program. CONCLUSIONS AND CLINICAL RELEVANCE: Mean prevalence of lesions typical of TB in dairy cattle at 6 locations in Mexico was 16%. Mycobacterium infection was confirmed by various techniques in most lesions. Recognition of typical gross lesions at slaughter may expedite TB control procedures.

Demonstration of Tritrichomonas foetus in the external genitalia and of specific antibodies in preputial secretions of naturally infected bulls.

Portions of penis and prepuce were collected from 24 bulls with current or recent Tritrichomonas foetus infection. Epididymides were collected from seven of the bulls, and seminal vesicles and prostate were collected from four. Following immunohistochemical staining with two monoclonal antibodies (34.7C4.4 and TF1.15) prepared against T. foetus surface antigens, trichomonads were identified in sections from 15 of the bulls. Organisms were most often located in penile crypts in the midshaft and caudal regions and less often in preputial crypts. Trichomonads were not observed in sections from other genitalia or in subepithelial tissue. T. foetus antigen, however, was present in the cytoplasm of some epithelial cells and the cytoplasm of some mononuclear cells in subepithelial lymphoid aggregates and follicles. Preputial smegma was collected from 16 T. foetus-infected bulls and from 16 control bulls with negative T. foetus cultures. Preputial antibody levels to TF1.17, a surface antigen of T. foetus, were determined by an enzyme-linked immunosorbent assay. Preputial secretions from infected bulls contained specific antibody of each isotype and subisotype tested. IgG1 responses were the greatest, IgM and IgA responses were approximately equal, and IgG2 responses were low. Each isotype and subisotype response in infected bulls was significantly greater than that in the controls. These results confirm previous speculation concerning anatomical sites of infection and suggest that parasite antigen can be taken up and processed locally, resulting in deposition of specific IgG1, IgG2, IgA, and IgM antibodies in the preputial cavity.

Biosafety and antibody responses of adult bison bulls after vaccination with Brucella abortus strain RB51.

OBJECTIVE: To evaluate clearance, antibody responses, potential shedding, and histologic lesions in reproductive tissues of adult bison bulls after vaccination with Brucella abortus strain RB51. ANIMALS: 61 two- and 3-year-old bison bulls. PROCEDURE: 12 bison bulls were vaccinated s.c. with B abortus strain RB51, 3 were inoculated s.c. with 0.15 M NaCl, and antibody responses were evaluated. Various specimens were obtained to evaluate bacterial shedding. Four vaccinates and 1 control were necropsied 10, 20, and 30 weeks after vaccination. In a separate experiment, bison bulls were vaccinated s.c. with 0.15 M NaCl, or by hand or ballistically with strain RB51. Antibody responses were monitored 6 weeks after vaccination and during necropsy 13 weeks after vaccination. Tissue specimens obtained during necropsy from both studies were evaluated bacteriologically and histologically. RESULTS: Strain RB51 was recovered at various times from semen of 3 of 12 vaccinated bison bulls in experiment 1. During necropsy, strain RB51 was recovered 10 and 20, but not 30, weeks after vaccination. In experiment 2, strain RB51 was recovered from lymphoid tissues of hand- and ballistic-vaccinated bison bulls during necropsy. In both experiments, microscopic lesions in testes, epididymis, and seminal vesicles were minimal and did not differ between strain RB51-vaccinated and saline-inoculated bison bulls. CONCLUSIONS AND CLINICAL RELEVANCE: Strain RB51 does not induce relevant inflammatory lesions in reproductive tissues of adult bison bulls. Shedding of strain RB51 in semen may be transient in some bison bulls; however, the importance of this observation is unknown.

Granuloma development in cattle after intratonsilar inoculation with Mycobacterium bovis.

OBJECTIVE: To examine the temporal development of tuberculous lesions in cattle inoculated with Mycobacterium bovis. ANIMALS: 15 mature crossbred cows obtained from a herd with no history of M bovis infection. PROCEDURE: Inoculation of cattle was done by intratonsilar instillation of 1.48 X 10(5) to 5.4 X 10(7) colony-forming units of M bovis strain 2045T. At 3 to 4 hours, 4 weeks, 6 weeks, and 8 weeks after inoculation, tissues were examined for gross and microscopic lesions and processed for isolation of M bovis. RESULTS: Retropharyngeal lymph nodes from cattle examined 4 weeks after inoculation contained microgranulomas consisting of aggregates of macrophages with few neutrophils. Retropharyngeal lymph nodes from all cattle examined 6 and 8 weeks after inoculation contained multiple, large, coalescing granulomas consisting of central areas of necrosis with mild fibrosis, numerous macrophages, lymphocytes, plasma cells, multinucleated giant cells, and neutrophils. Three of 8 cattle examined 6 or 8 weeks after inoculation had lesions in nonretropharyngeal sites with morphologic characteristics similar to that seen in retropharyngeal lymph node granulomas from cattle examined 4 weeks after inoculation. CONCLUSION: Granulomas can develop in draining lymph nodes of cattle in as little as 4 weeks after inoculation via intratonsilar instillation of M bovis. Intralesional morphologic changes between 4 and 6 weeks after inoculation indicate an increase in cellular chemotaxis and differentiation. Dissemination of bacteria to distant sites most likely was by lymphatic and hematogenous routes after establishment of the primary infection in retropharyngeal lymph nodes.

Comparison of diagnostic methods for detection of active infection with Tritrichomonas foetus in beef heifers.

OBJECTIVE: To compare sensitivity of a generic trypticase-yeast extract-maltose (TYM) medium versus a commercial nutrient medium in the diagnosis of Tritrichomonas foetus infection in heifers and to assess sensitivity when incubation of samples inoculated into commercial medium pouches is delayed overnight. DESIGN: Prospective study. ANIMALS: 30 virgin beef heifers. PROCEDURES: 20 heifers vaccinated with a trichomonad antigen and 10 unvaccinated control heifers were exposed at synchronized estrus by intravaginal instillation of 10(6) T foetus organisms. Cervicovaginal mucus samples were collected every other week for 10 weeks from controls and once (10 weeks after exposure) from vaccinated heifers. Samples were inoculated into both media and immediately incubated at 37 C (98.6 F). A duplicate inoculation from controls was made into commercial medium, and the pouch was shipped overnight to a diagnostic laboratory without prior incubation. RESULTS: For 40 of 50 samples from control heifers, there was agreement on diagnoses between media. There was agreement on a positive diagnosis for 3 of 20 samples from vaccinated heifers and on a negative diagnosis for 15 of these 20 samples. For samples shipped overnight before incubation, there were 10% fewer positive diagnoses, compared with samples incubated immediately in commercial medium and 10% more positive diagnoses, compared with samples immediately incubated in TYM. CLINICAL IMPLICATIONS: Use of the commercial medium is a more sensitive indicator of current infection in heifers than use of generic TYM medium. In herds where infection prevalence is high, this method is likely to identify more infected females, an important consideration when control programs include culling of infected cows.

Seminal vesiculitis and orchitis caused by Brucella abortus biovar 1 in young bison bulls from South Dakota.

Specimens of blood, lymph nodes, spleens, and genitalia were collected at slaughter from seven 3- and 4-year-old male bison that had recently become seropositive for brucellosis. The animals were from a captive herd of approximately 3,500 bison located in central South Dakota. Brucella abortus biovar 1 was isolated from 2 or more specimens from each of 6 bison. Severe necrotizing and pyogranulomatous orchitis was present in 1 testicle from 1 bull, and 4 animals had mild to marked seminal vesiculitis. Immunohistochemical staining labeled organisms in seminal vesicles and the testicle with orchitis. Ultrastructurally, intact bacilli were present in cytoplasmic vacuoles of some macrophages; other macrophages contained intracytoplasmic aggregates of calcified coccobacilli.