Brucella Infection in the Bull: A Progress Report of Mating Experiments With Naturally Infected Bulls

King, R. O. C.

doi:10.1111/j.1751-0813.1940.tb01297.x

Cited by 7 publications

(4 citation statements)

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“…In seropositive naturally-infected bulls, Hill ( 1983 ) found positive bacterial cultures of testes in 2/17 (12%) of animals. Shedding in the semen is not believed to be a major mode of transmission in domestic animals (King, 1940 ; FAO and WHO, 1986 ) but spread of the infection through artificial insemination has been reported (Bendixen and Blom, 1947 ; Manthei et al, 1950 ). In the American bison ( Bison bison ), low amounts of bacteria in the semen outside the mating period did not support this transmission route, but it cannot be excluded that the amount of bacteria could increase during the mating period (Frey et al, 2013 ).…”

Section: Discussionmentioning

confidence: 99%

High Shedding Potential and Significant Individual Heterogeneity in Naturally-Infected Alpine ibex (Capra ibex) With Brucella melitensis

et al. 2018

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Wildlife reservoirs of infectious diseases raise major management issues. In Europe, brucellosis has been eradicated in domestic ruminants from most countries and wild ruminants have not been considered important reservoirs so far. However, a high prevalence of Brucella melitensis infection has been recently identified in a French population of Alpine ibex (Capra ibex), after the emergence of brucellosis was confirmed in a dairy cattle farm and two human cases. This situation raised the need to identify the factors driving the persistence of Brucella infection at high prevalence levels in this ibex population. In the present paper, we studied the shedding pattern of B. melitensis in ibex from Bargy Massif, French Alps. Bacteriological examinations (1–15 tissues/samples per individual) were performed on 88 seropositive, supposedly infected and euthanized individuals. Among them, 51 (58%) showed at least one positive culture, including 45 ibex with at least one Brucella isolation from a urogenital sample or a lymph node in the pelvic area (active infection in organs in the pelvic area). Among these 45 ibex, 26 (30% of the total number of necropsied animals) showed at least one positive culture for a urogenital organ and were considered as being at risk of shedding the bacteria at the time of capture. We observed significant heterogeneity between sex-and-age classes: seropositive females were most at risk to excrete Brucella before the age of 5 years, possibly corresponding to abortion during the first pregnancy following infection such as reported in the domestic ruminants. The high shedding potential observed in young females may have contributed to the self-sustained maintenance of infection in this population, whereas males are supposed to play a role of transmission between spatial units through venereal transmission during mating. This heterogeneity in the shedding potential of seropositive individuals should be considered in the future to better evaluate management scenarios in this system as well as in others.

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Section: Discussionmentioning

confidence: 99%

High Shedding Potential and Significant Individual Heterogeneity in Naturally-Infected Alpine ibex (Capra ibex) With Brucella melitensis

et al. 2018

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“…Brucella abortus causes abortions and is transmitted within and among wildlife and livestock when individuals investigate or feed near infected fetuses, placentas, or birthing fluids (Cheville et al 1998). Bulls are considered relatively unimportant to disease dynamics because several studies have failed to document sexual transmission from males to females in either cattle or bison (Lubbenhusin and Fitch 1926, King 1940, Thomsen 1943, Bendixen and Blom 1947, Robison 1994. Another mode of transmission is through milk as infected females nurse their calves (Cheville et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Probable causes of increasing brucellosis in free‐ranging elk of the Greater Yellowstone Ecosystem

Cross

Cole

Dobson

et al. 2010

Ecological Applications

122

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While many wildlife species are threatened, some populations have recovered from previous overexploitation, and data linking these population increases with disease dynamics are limited. We present data suggesting that free-ranging elk (Cervus elaphus) are a maintenance host for Brucella abortus in new areas of the Greater Yellowstone Ecosystem (GYE). Brucellosis seroprevalence in free-ranging elk increased from 0-7% in 1991-1992 to 8-20% in 2006-2007 in four of six herd units around the GYE. These levels of brucellosis are comparable to some herd units where elk are artificially aggregated on supplemental feeding grounds. There are several possible mechanisms for this increase that we evaluated using statistical and population modeling approaches. Simulations of an age-structured population model suggest that the observed levels of seroprevalence are unlikely to be sustained by dispersal from supplemental feeding areas with relatively high seroprevalence or an older age structure. Increases in brucellosis seroprevalence and the total elk population size in areas with feeding grounds have not been statistically detectable. Meanwhile, the rate of seroprevalence increase outside the feeding grounds was related to the population size and density of each herd unit. Therefore, the data suggest that enhanced elk-to-elk transmission in free-ranging populations may be occurring due to larger winter elk aggregations. Elk populations inside and outside of the GYE that traditionally did not maintain brucellosis may now be at risk due to recent population increases. In particular, some neighboring populations of Montana elk were 5-9 times larger in 2007 than in the 1970s, with some aggregations comparable to the Wyoming feeding-ground populations. Addressing the unintended consequences of these increasing populations is complicated by limited hunter access to private lands, which places many ungulate populations out of administrative control. Agency-landowner hunting access partnerships and the protection of large predators are two management strategies that may be used to target high ungulate densities in private refuges and reduce the current and future burden of disease.

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“…Fifty to sixty percent of infected female elk abort their first calf post-infection [20] , but only one in nine elk lose a second calf [21] . Studies in elk [20] , bison [22] , and cattle [23] , [24] , [25] have failed to show sexual transmission of B. abortus . In both bison and elk, calves born to infected mothers tend to be initially seropositive but are seronegative by six months old suggesting maternal antibodies rather than vertical transmission [20] , [26] .…”

Section: Introductionmentioning

confidence: 99%

Mapping Brucellosis Increases Relative to Elk Density Using Hierarchical Bayesian Models

et al. 2010

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The relationship between host density and parasite transmission is central to the effectiveness of many disease management strategies. Few studies, however, have empirically estimated this relationship particularly in large mammals. We applied hierarchical Bayesian methods to a 19-year dataset of over 6400 brucellosis tests of adult female elk (Cervus elaphus) in northwestern Wyoming. Management captures that occurred from January to March were over two times more likely to be seropositive than hunted elk that were killed in September to December, while accounting for site and year effects. Areas with supplemental feeding grounds for elk had higher seroprevalence in 1991 than other regions, but by 2009 many areas distant from the feeding grounds were of comparable seroprevalence. The increases in brucellosis seroprevalence were correlated with elk densities at the elk management unit, or hunt area, scale (mean 2070 km2; range = [95–10237]). The data, however, could not differentiate among linear and non-linear effects of host density. Therefore, control efforts that focus on reducing elk densities at a broad spatial scale were only weakly supported. Additional research on how a few, large groups within a region may be driving disease dynamics is needed for more targeted and effective management interventions. Brucellosis appears to be expanding its range into new regions and elk populations, which is likely to further complicate the United States brucellosis eradication program. This study is an example of how the dynamics of host populations can affect their ability to serve as disease reservoirs.

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Brucella Infection in the Bull: A Progress Report of Mating Experiments With Naturally Infected Bulls

Cited by 7 publications

References 0 publications

High Shedding Potential and Significant Individual Heterogeneity in Naturally-Infected Alpine ibex (Capra ibex) With Brucella melitensis

High Shedding Potential and Significant Individual Heterogeneity in Naturally-Infected Alpine ibex (Capra ibex) With Brucella melitensis

Probable causes of increasing brucellosis in free‐ranging elk of the Greater Yellowstone Ecosystem

Mapping Brucellosis Increases Relative to Elk Density Using Hierarchical Bayesian Models

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