Brucellosis in Elk. Ii. Clinical Effects and Means of Transmission as Determined Through Artificial Infections

Thorne, E. Tom; Morton, Jamie; Blunt, Floyd M.; Dawson, Huey A.

doi:10.7589/0090-3558-14.3.280

Cited by 56 publications

(77 citation statements)

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“…In addition, nearly 25% of the infected animals that were removed from Rainey Creek and allowed to calve aborted or produced stillborn calves, which is similar to elk from western Wyoming that were infected with field strain B. abortus (Thorne, 1978). If this rate of reproductive loss is typical of infected free-ranging elk in northeastern Idaho, the presence of brucellosis may significantly impact population dynamics of elk in these herds.…”

Section: Discussionmentioning

confidence: 99%

Brucellosis in Elk of Eastern Idaho

Etter

Drew

2006

Journal of Wildlife Diseases

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ABSTRACT:Brucellosis occurs in free-ranging elk (Cervus elaphus) and bison (Bison bison) in the Greater Yellowstone Area, which includes portions of Idaho, Wyoming, and Montana. Brucella abortus was first detected in elk in Idaho in 1998, and from 1998 to 2002, serologic surveillance of hunter-killed elk was conducted in northeastern and southeastern Idaho. Prevalence of antibodies in these elk varied annually, but averaged between 2% and 3%. Elk were also trapped in northeastern Idaho from 1998-2002 and tested for brucellosis using serology and tissue culture. In areas where artificial feeding of elk was done, antibody prevalence ranged from 12% to 80% depending on site, age, and sex. At one feeding site (Rainey Creek), a decline in the prevalence of antibodies (from 56.8% in 1999 to 13.5% in 2002) was detected after the removal of seropositive elk over 4 yr. Seropositive elk removed from two artificial winter feeding sites (Rainey Creek and Conant Creek) were euthanized and sampled or held in captivity and allowed to calve prior to euthanasia and necropsy. At necropsy, B. abortus biovar 1 and B. abortus biovar 4 were isolated from both cows and calves; however, biovar 4 was predominant. A dual infection with both biovars was found in one calf born to a seropositive cow from which biovar 4 was isolated. Abortions (16%), stillbirths (8%), and weak calves (4%) were observed in these elk. These findings confirm the presence of brucellosis in elk in eastern Idaho and provide information on disease management options.

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Section: Discussionmentioning

confidence: 99%

Brucellosis in Elk of Eastern Idaho

Etter

Drew

2006

Journal of Wildlife Diseases

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“…are gram-negative, facultative, intracellular bacteria which cause disease in a wide variety of domestic and wild animal species including cattle, bison (Bison bison), elk (Cervus elaphus), and moose (Alces alces; Creech, 1930;Thorne and Morton, 1978). In particular, B. abortus invades the mucous membranes of ungulates and can cause placentitis, with late-gestation abortions in females and orchitis and epididymitis in males (Bercovich, 1998).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Western Immunoblot as a Detection Method for Brucella Abortus Exposure in Elk

Schumaker

Mazet

Gonzales

et al. 2010

Journal of Wildlife Diseases

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ABSTRACT:Brucella abortus has been an important wildlife disease issue for most of the last century, especially because wildlife species are considered to be important disease reservoirs for cattle. Diagnostic uncertainty, caused in part by cross-reactions of antibodies to environmental pathogens such as Yersinia enterocolitica O:9 on standard Brucella serology, has exacerbated the challenges of managing the disease and has highlighted the need for test validation in wildlife species. The western immunoblot was evaluated for use in detecting B. abortus exposure in elk (Cervus elaphus) and for ruling out exposure to cross-reacting bacteria. Samples collected from 2003 to 2006, including 54 female and immature elk from four different elk herds, were tested using standard Brucella serologic methods (card, rapid automated presumptive [RAP], and rivanol tests), as well as the western immunoblot. Samples (n528) from animals known to be naturally infected with B. abortus biovar 1 served as positive controls. For presumed negative samples, sera (n526) were collected from two elk herds in which negative serologic tests, and the absence of clinical signs of disease such as abortions, supported Brucella-negative classification. In addition to these study samples, serologic data from 12 tule elk (Cervus elaphus nannodes) were provided from the California Department of Fish and Game in order to illustrate a field application of the western blot. The western immunoblot had the highest sensitivity (1.0;% 0.899-1.0) and specificity (1.0; 0.891-1.0) among all tests used in the study. The Kappa statistic for agreement between the western blot and the card, rivanol, and RAP tests were 0.701, 0.808, and 0.921, respectively, showing good to excellent agreement with the standard diagnostic tests currently in use. Although the western immunoblot is more expensive and time intensive than other tests, in this limited study, it was shown to be reliable for establishing and confirming B. abortus disease status in elk. In addition to this study, subsequent applications of the western blot assay have been successful in detecting Yersinia sp. exposure in elk after their antibodies cross-reacted on standard Brucella serology.

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“…During this period, brucellosis causes roughly half of infected females to abort their first pregnancy postinfection and roughly 10% to also abort their second calf (Thorne et al 1978). From these abortion events, transmission occurs via uptake of the bacteria through contact with or feeding near the fetus or birthing materials (Cheville et al 1998), but evidence suggests the duration of exposure may be limited because scavengers typically consume aborted materials within 24 to 48 hours (Cook et al 2004, Maichak et al 2009).…”

Section: Introductionmentioning

confidence: 99%

“…However, the effects of such long-term contamination on transmission are not known. Other modes of directly transmitting bacteria such as vertical or sexual transmission are not considered important in the spread of B. abortus (Thorne et al 1978).…”

Section: Introductionmentioning

confidence: 99%

A multi‐scale assessment of animal aggregation patterns to understand increasing pathogen seroprevalence

Brennan¹,

Cross²,

Higgs³

et al. 2014

Ecosphere

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Abstract. Understanding how animal density is related to pathogen transmission is important to develop effective disease control strategies, but requires measuring density at a scale relevant to transmission. However, this is not straightforward or well-studied among large mammals with group sizes that range several orders of magnitude or aggregation patterns that vary across space and time. To address this issue, we examined spatial variation in elk (Cervus canadensis) aggregation patterns and brucellosis across 10 regions in the Greater Yellowstone Area where previous studies suggest the disease may be increasing. We hypothesized that rates of increasing brucellosis would be better related to the frequency of large groups than mean group size or population density, but we examined whether other measures of density would also explain rising seroprevalence. To do this, we measured wintering elk density and group size across multiple spatial and temporal scales from monthly aerial surveys. We used Bayesian hierarchical models and 20 years of serologic data to estimate rates of increase in brucellosis within the 10 regions, and to examine the linear relationships between these estimated rates of increase and multiple measures of aggregation. Brucellosis seroprevalence increased over time in eight regions (one region showed an estimated increase from 0.015 in 1991 to 0.26 in 2011), and these rates of increase were positively related to all measures of aggregation. The relationships were weaker when the analysis was restricted to areas where brucellosis was present for at least two years, potentially because aggregation was related to disease-establishment within a population. Our findings suggest that (1) group size did not explain brucellosis increases any better than population density and (2) some elk populations may have high densities with small groups or lower densities with large groups, but brucellosis is likely to increase in either scenario. In this case, any one control method such as reducing population density or group size may not be sufficient to reduce transmission. This study highlights the importance of examining the density-transmission relationship at multiple scales and across populations before broadly applying disease control strategies.

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Brucellosis in Elk. Ii. Clinical Effects and Means of Transmission as Determined Through Artificial Infections

Abstract: Abstract:The effects of brucebbosis in 60 mature elk (Cervus canadensis) and over 72 of their offspring were determined over a 65-month period.

Cited by 56 publications

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Brucellosis in Elk of Eastern Idaho

Brucellosis in Elk of Eastern Idaho

Evaluation of the Western Immunoblot as a Detection Method for Brucella Abortus Exposure in Elk

A multi‐scale assessment of animal aggregation patterns to understand increasing pathogen seroprevalence

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