A case of bacteremia and pneumonia caused by Streptococcus equi subspecies equi infection in a 70-year-old female following horse exposure in rural Wyoming.

BACKGROUND: The occurrence of zoonotic infections following an animal exposure continues to be an important consideration for all patients, especially those within agricultural communities. Streptococcus equi subspecies equi (S. equi subsp. equi) is a bacteria known to cause a common infection called 'Strangles' in horses. This article highlights a new case of pneumonia and bacteremia in a patient caused by S. equi subsp. equi following strangles exposure in a horse. Rarely has there been reported horse to human transmission of subsp. equi. CASE PRESENTATION: A 70-year-old woman attended a rural emergency department with complaints of dry heaving, fever, chills, shakes, and nausea and presented with a cough. She had undergone a screening colonoscopy two days prior with no other significant medical history. The patient had computed tomography (CT) evidence of a pneumonia and positive blood cultures growing S. equi subsp. equi consistent with bacteremia. The patient later disclosed the recent passing of her horse following its sudden illness six days prior to her emergency department presentation. She had cuddled and kissed the horse prior to its death. The patient was treated with IV lactated ringers during the initial evaluation and admission and also received IV piperacillin-tazobactam 4.5 g every eight hours intravenously during her hospital stay. She was transitioned to an oral antibiotic on discharge. Subsequent blood cultures drawn the day after discharge were negative for S. equi subsp. equi, indicating successful treatment of her bacteremia. CONCLUSIONS: This report discusses an atypical presentation of S. equi subsp. equi infection in an otherwise healthy individual, manifesting as early sepsis, pneumonia, and bacteremia. The patient likely developed this infection following direct contact exposure to her horse who had died from presumed strangles a few days prior to her symptom onset. This case highlights the importance of investigating potential exposures to S. equi subsp. equi in rural areas, areas where farming and ranching are prevalent, particularly among individuals working with horses. It is especially important to acknowledge high risk populations such as immunocompromised individuals with signs and symptoms of meningitis or bacteremia.

DETECTION OF DEER ATADENOVIRUS A DNA IN DAM AND OFFSPRING PAIRS OF ROCKY MOUNTAIN MULE DEER (ODOCOILEUS HEMIONUS HEMIONUS) AND ROCKY MOUNTAIN ELK (CERVUS CANADENSIS NELSONI).

Adenovirus hemorrhagic disease affects primarily mule deer (Odocoileus hemionus), white-tailed deer (Odocoileus virginianus), Rocky Mountain elk (Cervus canadensis nelsoni), and moose (Alces alces) in their first year of life. The method by which the causative virus, Deer atadenovirus A, is maintained in the environment and transmitted to neonates is unknown. In this study, we investigated the potential transmission of the virus from dam to offspring in Rocky Mountain mule deer (Odocoileus hemionus hemionus) and elk in western Wyoming, US. We sampled dams before parturition during placement of vaginal implant transmitters and at parturition and sampled neonates during capture in their first days of life. We also tested for the virus in mortalities submitted for pathologic examination and laboratory analysis. We detected viral DNA in samples from all time points tested but did not find a connection between positive dams and offspring mortalities associated with adenovirus hemorrhagic disease. Although we did not find direct evidence of transmission events between dams and offspring, asymptomatic animals shedding of Deer atadenovirus A, are a likely source of infection in neonates.

X-Linked Hypohidrotic Ectodermal Dysplasia in Crossbred Beef Cattle Due to a Large Deletion in EDA.

X-linked hypohidrotic ectodermal dysplasia-1 (ECTD1) in people results in a spectrum of abnormalities, most importantly hypotrichosis, anodontia/oligodontia, and absent or defective ectodermally derived glands. Five Red Angus-Simmental calves born over a 6-year period demonstrated severe hypotrichosis and were diagnosed as affected with ECTD1-like syndrome. Two died of severe pneumonia within a week of birth. The skin of three affected calves revealed a predominance of histologically unremarkable small-caliber hair follicles. Larger follicles (>50 µm) containing medullated hairs (including guard and tactile hairs) were largely restricted to the muzzle, chin, tail, eyelids, tragus and distal portions of the limbs and tail. The mean histological density of hair follicles in flank skin of two affected calves was slightly greater than that in two unaffected calves. One affected calf was examined postmortem at 10 days of age to better characterize systemic lesions. Nasolabial, intranasal and tracheobronchial mucosal glands were absent, whereas olfactory glands were unaffected. Mandibular incisor teeth were absent. Premolar teeth were unerupted and widely spaced. Other than oligodontia, histological changes in teeth were modest, featuring multifocal disorganization of ameloblasts, new bone formation in dental alveoli, and small aggregates of osteodentin and cementum at the margins of the enamel organ. A 52,780 base pair deletion spanning six out of eight coding exons of EDA and all of AWAT2 was identified. Partial deletion of the EDA gene is the presumed basis for the reported X-chromosomal recessive inherited genodermatosis.

Comparison of 2 ELISAs for detecting exposure to Brucella ovis.

Control of Brucella ovis infection in sheep flocks in the United States depends on early detection of B. ovis antibodies via serologic testing. We used 2,276 sheep sera and various cutoff values to compare seroprevalence and agreement between 2 ELISAs: the National Veterinary Services Laboratories (NVSL) B. ovis indirect ELISA and the IDEXX B. ovis ELISA kit. A subset of 295 sera was used to compare agreement and evaluate relative sensitivity and specificity of the 2 ELISAs with an agar gel immunodiffusion (AGID) test kit. There was no significant difference in B. ovis seroprevalence between the ELISAs; however, there was poor agreement between them. When the AGID test was used as the reference test, the IDEXX ELISA with a moderate cutoff value (S/P ratio = 45%) had the highest relative sensitivity of 38.1% and specificity of 92.0%. The NVSL ELISA with a lax cutoff value (S/P ratio = 0.75) had relative sensitivity of 19.1% and specificity of 94.6%. Receiver operating characteristic analysis revealed that optimal cutoff values for the NVSL and IDEXX ELISAs were 0.091 and 16.5%, respectively. This results in sensitivity and specificity of 85.7% and 31.8% for the NVSL ELISA, and sensitivity and specificity of 81.0% and 53.6% for the IDEXX ELISA, respectively.

Chronic wasting disease undermines efforts to control the spread of brucellosis in the Greater Yellowstone Ecosystem.

Wildlife diseases pose a substantial threat to the provisioning of ecosystem services. We use a novel modeling approach to study the potential loss of these services through the imminent introduction of chronic wasting disease (CWD) to elk populations in the Greater Yellowstone Ecosystem (GYE). A specific concern is that concentrating elk at feedgrounds may exacerbate the spread of CWD, whereas eliminating feedgrounds may increase the number of elk on private ranchlands and the transmission of a second disease, brucellosis, from elk to cattle. To evaluate the consequences of management strategies given the threat of two concurrent wildlife diseases, we develop a spatiotemporal bioeconomic model. GPS data from elk and landscape attributes are used to predict migratory behavior and population densities with and without supplementary feeding. We use a 4,800 km2 area around Pinedale, Wyoming containing four existing feedgrounds as a case study. For this area, we simulate welfare estimates under a variety of management strategies. Our results indicate that continuing to feed elk could result in substantial welfare losses for the case-study region. Therefore, to maximize the present value of economic net benefits generated by the local elk population upon CWD's arrival in the region, wildlife managers may wish to consider discontinuing elk feedgrounds while simultaneously developing new methods to mitigate the financial impact to ranchers of possible brucellosis transmission to livestock. More generally, our methods can be used to weigh the costs and benefits of human-wildlife interactions in the presence of multiple disease risks.

Seroprevalence and risk factors of Brucella ovis in domestic sheep in Wyoming, USA.

BACKGROUND: Brucella ovis causes a sexually transmitted, infectious disease of domestic sheep characterized by genital lesions and epididymitis in rams, placentitis and rare abortions in ewes, and neonatal mortality in lambs. This study was designed to 1) estimate animal and flock seroprevalence of B. ovis in sheep across Wyoming, USA, and 2) describe epidemiologic risk factors associated with seropositive sheep and flocks. For the animal seroprevalence estimate, 2423 blood samples were collected from sheep on 18 producer-selected operations and a questionnaire about possible risk factors was distributed. For the flock seroprevalence estimate, blood samples from 82 operations were obtained, including samples from the previous 18 operations and 64 additional operations that sent samples to the Wyoming State Veterinary Laboratory for diagnostic testing. Categorical risk factors were created based on questionnaires and submission forms. Sera was analyzed using the B. ovis enzyme-linked immunosorbent assay. RESULTS: Estimated true animal and flock seroprevalence were 0.53% (95% CI: 0.21-1.01%; 22/2,423) and 22.5% (95% CI: 14-32%; 18/82), respectively. Using Fisher's exact and Mid-p exact tests to compare apparent seroprevalence with respect to possible risk factors, increased age and breed type were risk factors associated with seropositive sheep, while region and large flock size were risk factors associated with seropositive flocks. CONCLUSIONS: Results from this study suggest few sheep have been exposed to B. ovis, but many flocks contain at least one seropositive animal. Each region in Wyoming contained at least one seropositive animal and flock, emphasizing the importance of disease-free documentation before purchasing new sheep. Aged sheep (≥ 6 years of age) had the highest seroprevalence among age groups; hence, we propose the separation of young rams from older rams to help reduce disease spread outside the breeding season. Wool breeds (Rambouillet and Merino) may be less susceptible to B. ovis infection given they had the lowest animal seroprevalence of the breed types, and large flocks (> 100 breeding rams) had the highest seroprevalence of the flock size categories, likely due to more intensive management strategies that can contribute to the introduction and persistence of B. ovis infection in sheep and flocks.

Comparisons of brucellosis between human and veterinary medicine.

Brucellosis is the world's most widespread zoonosis, but also ranks as one of the seven most neglected diseases, according to the World Health Organization. Additionally, it is recognized as the world's most common laboratory-acquired infection. There are a reported 500,000 incident cases of human brucellosis per year. However, true incidence is estimated to be 5,000,000 to 12,500,000 cases annually. Once diagnosed, focus is directed at treating individual patients with antibiotic regimes, yet overall neglecting the animal reservoir of disease. Countries with the highest incidence of human brucellosis are Syria (1,603.4 cases per 1,000,000 individuals), Mongolia (391.0), and Tajikistan (211.9). Surveillance on animal populations is lacking in many developed and developing countries. According to the World Animal Health Information Database, Mexico had the largest number of reported outbreaks, 5,514 in 2014. Mexico is followed by China (2,138), Greece (1,268), and Brazil (1,142). The majority of these outbreaks is Brucella abortus, the etiologic agent of bovine brucellosis. Brucellosis is an ancient disease that still plagues the world. There are still knowledge gaps and a need for better diagnostics and vaccines to make inroads towards control and eradication.

Adenoviral hemorrhagic disease in California mule deer, 1990-2014.

We reviewed case records from the California Animal Health and Food Safety (CAHFS) laboratory and the California Department of Fish and Wildlife (CDFW) spanning 25 years (1990-2014) for all deer accessions submitted to CAHFS for pathology and/or histopathology, with and without a diagnosis of adenoviral hemorrhagic disease (AHD), in order to determine the prevalence of AHD in California. We also examined spatial and temporal distribution, age, and mule deer subspecies in deer that died from AHD. Of 483 deer submitted to CAHFS for diagnostic testing in 1990-2014, 17.2% were diagnosed with confirmed AHD, and 26.5% were confirmed plus suspected cases of AHD. Columbian black-tailed deer ( Odocoileus hemionus columbianus), particularly fawns and juveniles, were most frequently affected. Deer adenovirus ( Odocoileus adenovirus 1; OdAdV-1) was detected by immunohistochemistry in archived CDFW formalin-fixed, paraffin-embedded tissues from deer that died in mortality events in 1981, 1983, and 1986-1987. OdAdV-1 is a common cause of hemorrhagic disease mortality events in California deer, and mortality as a result of AHD is documented as early as 1981.

Optimization of Brucella abortus Protocols for Downstream Molecular Applications.

We compared the performances of various DNA extraction kits for their ability to recover Brucella abortus strain 19 inoculated into Brucella-free bovine tissues. Tissues were homogenized in a FastPrep bead homogenizer and extracted in triplicate by using one of five kits (Qiagen DNeasy, GE Illustra, Omega Bio-tek E.Z.N.A., Quanta Extracta, and IBI Science DNA Tissue kit). Whole blood was also taken from animals prior to chemical euthanasia, aliquoted, and then fractioned into buffy coat, red blood cells, and plasma. DNA was extracted from whole blood, buffy coat, and plasma by using four kits (Qiagen DNeasy, Omega Bio-tek E.Z.N.A., IBI Science DNA Blood kit, and 5PRIME PerfectPure). Previously reported primers targeting strain 19 were used to amplify extracted DNA and identify the optimal extraction kit. Real-time PCR was performed, and kits were compared for statistical differences by using quantification cycles as an outcome measure. Omega Bio-tek E.Z.N.A. was superior (P < 0.0068) in its lower quantification cycle values across all tissue kits. The IBI Science DNA Blood kit was superior to Qiagen DNeasy, 5PRIME PerfectPure, and Quanta Extracta (P < 0.0001, P = 0.0004, and P = 0.0013, respectively) but was not different from Omega Bio-tek E.Z.N.A. (P = 1.0). In summary, the optimal extraction kit for B. abortus strain 19 for tissues is Omega Bio-tek E.Z.N.A., and that for blood and its fractions is the IBI Science Mini Genomic DNA kit. Eluted DNA was also concentrated by using the Zymo Research DNA Clean & Concentrator-25 kit. Concentrated eluted DNA with the target was superior (P = <0.0001) to unconcentrated eluted DNA.

Endemic chronic wasting disease causes mule deer population decline in Wyoming.

Chronic wasting disease (CWD) is a fatal transmissible spongiform encephalopathy affecting white-tailed deer (Odocoileus virginianus), mule deer (Odocoileus hemionus), Rocky Mountain elk (Cervus elaphus nelsoni), and moose (Alces alces shirasi) in North America. In southeastern Wyoming average annual CWD prevalence in mule deer exceeds 20% and appears to contribute to regional population declines. We determined the effect of CWD on mule deer demography using age-specific, female-only, CWD transition matrix models to estimate the population growth rate (λ). Mule deer were captured from 2010-2014 in southern Converse County Wyoming, USA. Captured adult (≥ 1.5 years old) deer were tested ante-mortem for CWD using tonsil biopsies and monitored using radio telemetry. Mean annual survival rates of CWD-negative and CWD-positive deer were 0.76 and 0.32, respectively. Pregnancy and fawn recruitment were not observed to be influenced by CWD. We estimated λ = 0.79, indicating an annual population decline of 21% under current CWD prevalence levels. A model derived from the demography of only CWD-negative individuals yielded; λ = 1.00, indicating a stable population if CWD were absent. These findings support CWD as a significant contributor to mule deer population decline. Chronic wasting disease is difficult or impossible to eradicate with current tools, given significant environmental contamination, and at present our best recommendation for control of this disease is to minimize spread to new areas and naïve cervid populations.

Risk assessment and management of brucellosis in the southern greater Yellowstone area (II): Cost-benefit analysis of reducing elk brucellosis prevalence.

Recent cases of bovine brucellosis (Brucella abortus) in cattle (Bos taurus) and domestic bison (Bison bison) of the southern Greater Yellowstone Area (SGYA) have been traced back to free-ranging elk (Cervus elaphus). Several management activities have been implemented to reduce brucellosis seroprevalence in elk, including test-and-slaughter, low-density feeding at elk winter feedgrounds, and elk vaccination. It is unclear which of these activities are most cost-effective at reducing the risk of elk transmitting brucellosis to cattle. In a companion paper, a stochastic risk model was used to translate a reduction in elk seroprevalence to a reduction in the risk of transmission to cattle. Here, we use those results to estimate the expected economic benefits and costs of reducing seroprevalence in elk using three different management activities: vaccination of elk with Brucella strain 19 (S19), low-density feeding of elk, and elk test-and-slaughter. Results indicate that the three elk management activities yield negative expected net benefits, ranging from -$2983 per year for low-density feeding to -$595,471 per year for test-and-slaughter. Society's risk preferences will determine whether strategies that generate small negative net benefit, such as low-density feeding, are worth implementing. However, activities with large negative net benefits, such as test-and-slaughter and S19 vaccination, are unlikely to be economically worthwhile. Given uncertainty about various model parameters, we identify some circumstances in which individual management activities might generate positive expected net benefit.

Risk assessment and management of brucellosis in the southern greater Yellowstone area (I): A citizen-science based risk model for bovine brucellosis transmission from elk to cattle.

Livestock producers and state wildlife agencies have used multiple management strategies to control bovine brucellosis in the Greater Yellowstone Area (GYA). However, spillover from elk to domestic bison and cattle herds continues to occur. Although knowledge is increasing about the location and behavior of elk in the SGYA, predicting spatiotemporal overlap between elk and cattle requires locations of livestock operations and observations of elk contact by producers. We queried all producers in a three-county area using a questionnaire designed to determine location of cattle and whether producers saw elk comingle with their animals. This information was used to parameterize a spatially-explicit risk model to estimate the number of elk expected to overlap with cattle during the brucellosis transmission risk period. Elk-cattle overlap was predicted in areas further from roads and forest boundaries in areas with wolf activity, with higher slopes, lower hunter densities, and where the cost-distance to feedgrounds was very low or very high. The model was used to estimate the expected number of years until a cattle reactor will be detected, under alternative management strategies. The model predicted cattle cases every 4.28 years in the highest risk herd unit, a higher prediction than the one case in 26 years we have observed. This difference likely indicates that ongoing management strategies are at least somewhat effective in preventing potential elk-cattle brucellosis transmission in these areas. Using this model, we can infer the expected effectiveness of various management strategies for reducing the risk of brucellosis spillover from elk to cattle.

Chronic Wasting Disease Drives Population Decline of White-Tailed Deer.

Chronic wasting disease (CWD) is an invariably fatal transmissible spongiform encephalopathy of white-tailed deer, mule deer, elk, and moose. Despite a 100% fatality rate, areas of high prevalence, and increasingly expanding geographic endemic areas, little is known about the population-level effects of CWD in deer. To investigate these effects, we tested the null hypothesis that high prevalence CWD did not negatively impact white-tailed deer population sustainability. The specific objectives of the study were to monitor CWD-positive and CWD-negative white-tailed deer in a high-prevalence CWD area longitudinally via radio-telemetry and global positioning system (GPS) collars. For the two populations, we determined the following: a) demographic and disease indices, b) annual survival, and c) finite rate of population growth (λ). The CWD prevalence was higher in females (42%) than males (28.8%) and hunter harvest and clinical CWD were the most frequent causes of mortality, with CWD-positive deer over-represented in harvest and total mortalities. Survival was significantly lower for CWD-positive deer and separately by sex; CWD-positive deer were 4.5 times more likely to die annually than CWD-negative deer while bucks were 1.7 times more likely to die than does. Population λ was 0.896 (0.859-0.980), which indicated a 10.4% annual decline. We show that a chronic disease that becomes endemic in wildlife populations has the potential to be population-limiting and the strong population-level effects of CWD suggest affected populations are not sustainable at high disease prevalence under current harvest levels.

Comparison of the humoral response between sheep vaccinated with a killed-virus vaccine and those vaccinated with a modified-live virus vaccine against bluetongue virus serotype 17.

OBJECTIVE To compare the humoral response between sheep vaccinated with a killed-virus (KV) vaccine and those vaccinated with a modified-live virus (MLV) vaccine against bluetongue virus (BTV) serotype 17. DESIGN Randomized clinical trial followed by a field trial. ANIMALS 30 yearling crossbred ewes (phase 1) and 344 sheep from 7 Wyoming farms (phase 2). PROCEDURES In phase 1, ewes seronegative for anti-BTV antibodies received sterile diluent (control group; n = 10) or an MLV (10) or KV (10) vaccine against BTV-17 on day 0. Ewes in the KV group received a second dose of the vaccine on day 21. Ewes were bred 5 months after vaccination and allowed to lamb. Anti-BTV antibodies were measured in ewes at predetermined times after vaccination and in their lambs once at 5 to 10 days after birth. In phase 2, 248 commercial sheep were screened for anti-BTV antibodies and vaccinated with a KV vaccine against BTV-17 on day 0. Sheep seronegative for anti-BTV antibodies on day 0 (n = 90) underwent follow-up serologic testing on day 365 along with 96 unvaccinated cohorts (controls). RESULTS In phase 1, all vaccinated ewes developed anti-BTV antibodies by 14 days after vaccination and remained seropositive for 1 year; all of their lambs were also seropositive. All control ewes and lambs were seronegative. In phase 2, the prevalence of vaccinated sheep with anti-BTV antibodies 1 year after vaccination was 93% and 76% as determined by a serum neutralization assay and competitive ELISA, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Both vaccines induced antibodies against BTV-17 that persisted for at least 1 year and provided passive immunity for lambs and may be a viable option to protect sheep against disease.

Prevalence of and risk factors associated with ovine progressive pneumonia in Wyoming sheep flocks.

OBJECTIVE: To determine the prevalence of antibodies against small ruminant lentivirus (SRLV), the causative agent of ovine progressive pneumonia (OPP), and to identify risk factors associated with OPP in Wyoming sheep flocks. DESIGN: Cross-sectional study. ANIMALS: 1,415 sheep from 54 flocks in Wyoming. PROCEDURES: Flocks were surveyed as part of the National Animal Health Monitoring System (NAHMS) 2011 sheep study. Serum samples obtained from sheep in Wyoming were analyzed for anti-SRLV antibodies by use of a competitive-inhibition ELISA. The prevalence of seropositive animals overall and within each flock was calculated. Respective associations between flock OPP status and various demographic and management variables were assessed. RESULTS: The estimated prevalence of sheep seropositive for anti-SRLV antibodies and OPP-infected flocks in Wyoming was 18.0% and 47.5%, respectively. Within OPP-infected flocks, the prevalence of seropositive sheep ranged from 3.9% to 96%. Flocks maintained on nonfenced range were more likely to be infected with OPP than were flocks maintained on fenced range (OR, 3.4; 95% confidence interval, 1.1 to 10.7). The estimated prevalence of OPP-infected flocks in Wyoming did not vary substantially from that at the regional or national level reported in the NAHMS 2001 sheep study. Compared with results of the NAHMS 2011 sheep study, Wyoming producers were more familiar with OPP than were other US sheep producers, but only 61% of Wyoming producers surveyed reported being very or somewhat familiar with the disease. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that OPP is prevalent in many Wyoming sheep flocks, which suggested that continued efforts are necessary to increase producer knowledge about the disease and investigate practices to minimize economic losses associated with OPP.

Canine dysautonomia in a litter of Havanese puppies.

Canine dysautonomia is a sporadic, generally fatal disease that rarely affects groups of related animals. Four 10-week-old Havanese puppies from a litter of 5 developed clinical signs of canine dysautonomia. The 4 affected dogs were exposed to an outdoor environment, whereas the fifth littermate was not exposed to the outdoors and remained clinically healthy. Clinical signs of dysautonomia developed 10-16 days after going outside the house. An unrelated dog also developed dysautonomia after exposure to 1 of the affected Havanese littermates. All 5 dogs had morphological changes consistent with dysautonomia (widespread neuronal degeneration in autonomic ganglia, select brainstem nuclei, and ventral horn motor neurons). Differential diagnoses were excluded through negative toxicological evaluation, fecal parasite screening, negative Canine distemper virus reverse transcription polymerase chain reaction, fluorescent antibody testing, attempted virus isolation, and electron microscopy. The 5 affected dogs were in the Kansas City, Missouri area, where there is a high incidence of dysautonomia.

BAYESIAN ANALYSIS TO EVALUATE TESTS FOR THE DETECTION OF MYCOBACTERIUM BOVIS INFECTION IN FREE-RANGING WILD BISON (BISON BISON ATHABASCAE) IN THE ABSENCE OF A GOLD STANDARD.

We estimated the sensitivity and specificity of the caudal-fold skin test (CFT), the fluorescent polarization assay (FPA), and the rapid lateral-flow test (RT) for the detection of Mycobacterium bovis in free-ranging wild wood bison (Bison bison athabascae), in the absence of a gold standard, by using Bayesian analysis, and then used those estimates to forecast the performance of a pairwise combination of tests in parallel. In 1998-99, 212 wood bison from Wood Buffalo National Park (Canada) were tested for M. bovis infection using CFT and two serologic tests (FPA and RT). The sensitivity and specificity of each test were estimated using a three-test, one-population, Bayesian model allowing for conditional dependence between FPA and RT. The sensitivity and specificity of the combination of CFT and each serologic test in parallel were calculated assuming conditional independence. The test performance estimates were influenced by the prior values chosen. However, the rank of tests and combinations of tests based on those estimates remained constant. The CFT was the most sensitive test and the FPA was the least sensitive, whereas RT was the most specific test and CFT was the least specific. In conclusion, given the fact that gold standards for the detection of M. bovis are imperfect and difficult to obtain in the field, Bayesian analysis holds promise as a tool to rank tests and combinations of tests based on their performance. Combining a skin test with an animal-side serologic test, such as RT, increases sensitivity in the detection of M. bovis and is a good approach to enhance disease eradication or control in wild bison.

Risk factors associated with bovine trichomoniasis in beef cattle identified by a questionnaire.

Bovine trichomoniasis is a venereal disease that causes substantial economic losses to the cattle industry worldwide. It has been endemic in the USA since its discovery in the 1930s. The reasons for this long-lasting endemism are poorly understood. The main objective of this study was to identify herd-level risk factors for trichomoniasis in Wyoming beef cattle. A questionnaire was sent to all Wyoming beef cattle producers. The overall response proportion was 23.4 %. Questionnaires were returned from producers throughout the state in different geographical regions and with various herd sizes. In total, 863 questionnaires were analysed for correlation between the disease endemism and 25 variables. Tritrichomonas foetus infections were found to be significantly (P<0.05) associated with neighbouring a positive herd(s), grazing on public allotments and commingling with other herds. In addition, a delay in fixing broken fences approached statistical significance (P = 0.078). This study provides producers with valuable information and useful suggestions on how to effectively control and reduce the risks of bovine trichomoniasis.

Wildlife-livestock interactions in a western rangeland setting: quantifying disease-relevant contacts.

Disease transmission between wild ungulates and domestic livestock is an important and challenging animal health issue. The potential for disease transmission between wildlife and livestock is notoriously difficult to estimate. The first step for estimating the potential for between-species disease transmission is to quantify proximity between individuals of different species in space and time. This study estimates second-order statistics of spatio-temporal location data from radio-collared free-ranging deer, elk and cattle in northeast Oregon. Our results indicate, that when observed simultaneously, elk and cattle occur in closer proximity to each other than what would be expected based on general space use of these species. The same is true for deer and elk but not for deer and cattle. Our analysis also demonstrates that average distances between cattle and elk are largely driven by rare events of close co-mingling between the species, which extend over several hours. Behavioral causes for these co-mingling events are currently unknown. Understanding the causes for such events will be important for designing grazing practices that minimize wildlife-livestock contacts.

Outbreak investigation and control case report of brucellosis: experience from livestock research centre, Mpwapwa, Tanzania.

Brucellosis screening was conducted between 2005 and 2010 at the National Livestock Research Institute headquarters, Mpwapwa, Tanzania, following an abortion storm in cattle. The initial screening targeted breeding herds; 483 cattle were screened using the Rose Bengal Plate Test (RBPT) followed by the Competitive Enzyme-linked Immunosorbent Assay (c-ELISA) as a confirmatory test. The seropositivity on c-ELISA was 28.95% in 2005; it subsequently declined to 6.72%, 1.17%, 0.16% and 0.00% in 2006, 2007, 2009 and 2010, respectively. Brucella seropositivity was not detected in goats. Seropositivity declined following institution of stringent control measures that included: gradual culling of seropositive animals through slaughter; isolation and confinement of pregnant cows close to calving; proper disposal of placentas and aborted foetuses; the use of the S19 vaccine; and restricted introduction of new animals. It was thought that the source of this outbreak was likely to have been from the introduction of infected animals from another farm. Furthermore, humans were found with brucellosis antibodies. Out of 120 people screened, 12 (10%) were confirmed seropositive to brucella antigen exposure by c-ELISA analysis. The majority of the seropositive individuals (80%) were milkers and animal handlers from the farm. Nine individuals had clinical signs suggestive of brucellosis. All cases received medical attention from the district hospital. This achievement in livestock and human health showed that it is possible to control brucellosis in dairy farms, compared to pastoral and agro-pastoral farms, thus providing evidence to adopt these strategies in dairy farms thought to be at risk.