Brucellosis in Elk of Eastern Idaho

Abstract

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.

Status of Brucellosis in Free-Ranging Elk and Bison in Wyoming

“…Antibody prevalence in the BEF (n5 3,327, 21.9%) was greater than that of elk in the BEWFR (n53,787, 3.7%), whereas elk tested from the BNE (n51,930) were all negative. This is similar to the findings of Etter and Drew (2006), who reported elk captured on winter feedgrounds in Idaho, USA, had two to four times the antibody prevalence than elk not fed during winter and supports the general consensus among researchers and wildlife experts that winter feeding maintains brucellosis in elk.…”

“…Brucellosis was first detected in wildlife in 1917 when Mohler diagnosed the disease in YNP bison (Mohler, 1917), an infection that likely originated through contact with infected cattle or from infected bovine milk fed to captive bison calves (Cheville et al, 1998). Brucellosis was first detected in wild elk in 1930 (Murie, 1951) and, currently, appears to be well established in elk and bison in the GYE portions of Wyoming, Montana, and Idaho, USA (Tunnicliff and March, 1935;Thorne et al, 1997;Aune et al, 2002;Etter and Drew, 2006;United States Animal Health Association, 2006). Suspected B. abortus transmissions from elk to cattle in the GYE triggered Wyoming, Idaho, and Montana, USA, to lose their brucellosis Class Free cattle status in 2004, and 2008, respectively (Cross et al, 2007.…”

Big Game and Cattle Influence on Aspen Community Regeneration Following Prescribed Fire

“…However, this has not been the case for elk of the Greater Yellowstone area where feed ground practices that concentrate elk during the period when abortions are most likely have allowed the disease to persist and increase in prevalence (Thorne 2001). This finding has also been reported in Idaho, where the prevalence of brucellosis antibodies is two to four times higher in elk that use feed grounds (Etter and Drew 2006).…”

Molecular Epidemiology of Brucella abortus Isolates from Cattle, Elk, and Bison in the United States, 1998 to 2011

“…Seroprevalence rates among elk herds in the GYA range from 8 to 60%, while in bison herds, seroprevalence ranges from 11 to 75% (8,9,12,21,22,23). While the exact means by which cattle may acquire brucellosis from wildlife remains uncertain, it is thought that exposure to aborted fetuses and afterbirth ( Fig.…”