GREATER YELLOWSTONE INTERAGENCY BRUCELLOSIS COMMITTEE
TECHNICAL SUBCOMMITTEE
INFORMATIONAL PAPER


Interspecies Transmission of Brucella abortus

September 17, 1997

Index

Greater Yellowstone Interagency Brucellosis Technical
Subcommittee Working Group----------------------------------- Page iii

Introduction------------------------------------------------------ Page 1

History: B. abortus in Cattle in the United States
and Elk and Bison in the GYA------------------------------------ Page 3

Cattle-------------------------------------------------------- Page 3
Elk----------------------------------------------------------- Page 3
Bison--------------------------------------------------------- Page 4

Animal to Human Transmission----------------------------------- Page 6

History------------------------------------------------------- Page 6
Fund for Animals Survey-------------------------------------- Page 7
Alaska------------------------------------------------------- Page 7
Montana----------------------------------------------------- Page 7
Florida------------------------------------------------------- Page 8
Texas-------------------------------------------------------- Page 8

Brucellosis Classification and Epidemiology in Livestock
Herds----------------------------------------------------------- Page 9

Wildlife to Domestic Cattle Transmission------------------------ Page 10

I. Beef Cattle Herd------------------------------------------ Page 10
II. Beef Cattle and Bison Herd Unit------------------------- Page 12
III. Beef Cattle Herd---------------------------------------- Page 15
IV. Beef Cattle Herd---------------------------------------- Page 16
V. Beef Cattle Herd and Dairy Herd------------------------ Page 16
VI. Beef Cattle Herd, Parker Land & Cattle Company------ Page 17

Wildlife to Horse Transmission--------------------------------- Page 19

Wildlife to Wildlife Transmission------------------------------- Page 20

Experimental Transmission------------------------------------- Page 20

Bison, Texas A&M University Studies---------------------- Page 20
Elk, Wyoming Game and Fish Studies---------------------- Page 21

Appendix------------------------------------------------------ Page 22

Captive Wildlife To Domestic Cattle Transmission---------- Page 22
North Dakota, Beef/Dairy Bison Herd Unit------------- Page 22
Arkansas, Beef Cattle Herd---------------------------- Page 22
Domestic Cattle to Captive Wildlife Transmission---------- Page 23
Texas, Captive Bison Herd----------------------------- Page 23
Kansas, Captive Bison Herd--------------------------- Page 24

Personal Communication References-------------------------- Page 27

Information in this report was contributed by a Greater Yellowstone Interagency Brucellosis Committee working group. The report was compiled and edited by Donald R. Bridgewater, B.S., D.V.M., M.P.V.M., USDA-APHIS-Veterinary Services, Western Regional Office, Englewood, Colorado.

GREATER YELLOWSTONE INTERAGENCY BRUCELLOSIS TECHNICAL SUBCOMMITTEE WORKING GROUP

  1. Donald R. Bridgewater, B.S., D.V.M., M.P.V.M. (Chair)
    United States Department of Agriculture (USDA)
    Animal Plant Health Inspection Service (APHIS)
    Veterinary Services (VS)
    Western Regional Office (WRO)
    Colorado

  2. David L. Hunter, B.S., D.V.M.
    Idaho Department of Agriculture and
    Department of Fish and Game

  3. L. Michael Philo, A.B., V.M.D., Ph.D.
    USDA, APHIS, VS, WRO, Montana

  4. Scott G. Smith, B.S., M.S.
    Wyoming Game and Fish Department
  5. Larry L. Stackhouse, D.V.M., Ph.D.
    Department of Livestock, Veterinary Diagnostic
    Laboratory Division, Montana

  6. Tom Thorne, D.V.M.
    Wyoming Game and Fish Department

[INDEX]

INTRODUCTION

In 1997 the Greater Yellowstone Interagency Brucellosis Committee (GYIBC) prepared a White Paper on brucellosis, with emphasis on information related to bison and elk management in the Greater Yellowstone Area (GYA). This document summarized the information upon which the GYIBC member agencies could agree.

Brucellosis, as described in the White Paper, "is a contagious bacterial disease, caused by various species of the genus Brucella that infect domestic animals, wildlife, and humans worldwide." The disease can affect both livestock and wildlife. Brucella species and associated livestock hosts in the United States include B. abortus in cattle, B. suis in swine and reindeer, and B. ovis in sheep. B. melitensis infects goats, sheep and cattle worldwide but is not found in these species in the United States. In wildlife, B. abortus infects bison and elk, and B. suis infects caribou, moose, feral swine and wild swine.

Abortion of the first fetus after infection is the classic sign of brucellosis. It is also associated with other signs such as retained placenta, infertility, and reduced milk production. In cattle, transmission is well understood: in most cases infective organisms are ingested after contact with contaminated aborted fetuses, birth membranes, uterine fluids or vaginal discharges.

Brucellosis is a disease of economic importance to the livestock industry and a disease transmissible to humans. In both cases it is virtually incurable. Since the 1930s, a national program has been in place to eradicate brucellosis caused by B. abortus from livestock in the United States. Approximately $4 billion has been spent by the federal government, state governments and the livestock industry. The goal is to complete eradication by the end of 1998.

Transmission and other aspects of brucellosis are less well understood in elk and bison than in cattle. There have been several apparent cases of transmission from wildlife to cattle and transmission has been demonstrated under experimental conditions, but the subject of transmission from wildlife to cattle under range conditions remains controversial. The controversy is due in large part to the limited amount of information upon which to make predictions and management decisions.

The GYIBC attempts to collect and consolidate available information that could help in understanding brucellosis in the GYA. One aspect of brucellosis which the GYIBC has identified for consolidation of information is the subject of interspecies transmission.

This paper addresses the interspecies transmission of brucellosis caused by B. abortus between domestic bovine, domestic equine, captive bison, free-ranging wild elk and free-ranging wild bison. Moose were included because a generalized, fatal or potentially fatal disease caused by B. abortus has been documented in several moose (Corner and Connell 1958, Fenstermacher and Olsen 1942, Forbes et al. 1996, Jellison et al. 1953). Other wildlife species, e.g., deer, pronghorned antelope, mountain sheep, coyotes, wolves and bear, to name a few, are epidemiologically regarded to be of no significance in the maintenance and transmission of B. abortus.

References:

[INDEX]

HISTORY

CATTLE
"Contagious abortion became a serious problem for the people of New England as early as 1843. Some herds had a few abortions year after year, but when brucellosis first appeared in a herd, almost every pregnant cow would abort within 1 or 2 years. In addition to loss of the calf, the cow gave little milk and sometimes was sterile. As soon as Dr. Bang, the Danish veterinarian, reported the isolation of a small organism, Bacillus abortus (later revised to Bacterium abortum, then to Brucella abortus), from the placenta of aborting cows, the Bureau of Animal Industries (BAI) attempted to confirm the finding; in 1900, pure cultures of an organism were obtained from an outbreak of abortion in the cows of a hospital in the District of Columbia. In 1911, BAI veterinarians reported that they recovered the organism from the milk of apparently healthy cows and from tonsils removed from children. Dr. Melvin, Chief of the BAI, recognized the threat to public health and work on the disease was expanded." (Wisor et al. 1987) For a more detailed history of the national program to eradicate brucellosis in cattle and ranched bison, see the GYIBC brucellosis White Paper (GYIBC 1997).

[INDEX]

ELK
Historical evidence suggests that at least some of the Northern Yellowstone elk acquired brucellosis from bison (Rush 1932, Meagher and Meyer 1994). Rush (1932) concluded that elk undoubtedly wintered on the buffalo ranch feedground (located inside Yellowstone National Park early this century) with introduced bison and as a result of this mingling were exposed to the disease. He also reported the 1931 findings of elk sampled in proximity to the buffalo ranch. Six of 32 tested elk were considered seroreactors for the disease and he concluded brucellosis had become established in the herd. Tunnicliff and Marsh (1935) reported that approximately 22% of 105 elk tested from Yellowstone National Park (YNP) in 1931, 1932 and 1933 were serologically positive or suspicious.

Another possible source of brucellosis in the Northern Yellowstone elk was cattle. These elk move between Yellowstone National Park and nonpark areas of Montana. They could have been exposed to brucellosis-infected cattle during the years before Montana became a brucellosis Class Free state. The likelihood of exposure would have been particularly great before and in the early years of the brucellosis eradication program.

It is speculated that other elk in the Greater Yellowstone Area became exposed to Brucella from cattle after ranches were established on native winter ranges (Meagher and Meyer 1994, Thorne 1992, Thorne et al. 1995). Around the turn of the century, elk feeding with cattle on winter feedlines probably became exposed to the disease (Thorne 1992, Thorne et al. 1995). Brucellosis was first reported in elk on the National Elk Refuge, near Jackson, Wyoming, in 1930 when 3 of 9 animals were blood test positive (Murie 1951). Today the disease is still present in elk on the National Elk Refuge and 22 State of Wyoming feedgrounds in northwestern Wyoming.

The current status of brucellosis in elk in the Greater Yellowstone Area is discussed in the GYIBC Brucellosis White Paper (GYIBC 1997).

[INDEX]

BISON
Brucellosis was first diagnosed in bison of Yellowstone National Park (YNP) in 1917 when two females had positive agglutination reactions following abortion (Mohler 1917). However, no one knows how long the disease was present in Yellowstone bison before being diagnosed (Whittlesey 1994). Meagher and Meyer (1994) suggested that the origin of brucellosis in bison cannot be answered directly, but based on experts’ opinion, the general consensus is the disease was introduced by cattle. They reported the introduction of the disease to YNP bison probably took place at the Buffalo Ranch which was established in 1907. Rush (1932) reported several domestic cattle were maintained on part of the Buffalo Ranch until 1919. Whittlesey (1994) examined many archival records and found there had been many opportunities for contact between bison and cattle from 1872 through 1918. Contact was in the form of commingling in and around the park, feeding bison calves on domestic cows’ milk, and planned interbreeding. Based on recent testing from Montana and Wyoming, YNP bison continue to produce positive blood tests.

Free ranging bison that inhabit Grand Teton National Park (GTNP) and the surrounding area are commonly referred to as the Jackson Bison herd. According to Grand Teton National Park et al. (1996), in 1948, 20 bison from Yellowstone National Park were introduced into the Jackson Hole Wildlife Park. The park was a private, non-profit entity established to exhibit large mammals and provide a biological field station. In 1963, Brucella abortus infection was diagnosed in the herd. The thirteen adults were subsequently destroyed, leaving four calfhood-vaccinated yearlings and five vaccinated calves. In 1964, twelve certified brucellosis-free bison were added from Theodore Roosevelt National Park. In 1968 the herd, then numbering 15, escaped from their pen in the wildlife park.

Brucellosis tests conducted on the adults prior to escape were negative and the herd was assumed to be disease free (Williams et al. 1993). The Jackson Bison herd probably acquired brucellosis from one or more sources: infected but undiagnosed calves or adults in the original 15 bison or transmission from elk on the National Elk Refuge sometime after 1975 when bison began wintering on elk feedlines (Grand Teton National Park et al. 1996, Williams et al. 1993). Between 1989 and 1990, 27 of 35 bison sampled during a population reduction hunt were serologically positive (Williams et al. 1993). The Jackson Bison herd is still serologically positive.

References:

[INDEX]

ANIMAL TO HUMAN TRANSMISSION

Brucellosis is a zoonotic disease, i.e. it is transmissible from animals to humans. In the United States most cases of human brucellosis have been due to infection with B. abortus, B. suis and B. melitensis. Most human infections with B. abortus and B. suis have originated from contact with infected livestock. Historically the source of most B. abortus infections has been consumption of unpasteurized milk. Two recently documented cases of B. abortus transmission from wildlife to humans are described below. Human infection by B. suis has been associated with livestock and wildlife. B. melitnesis infections have originated outside the country.

The zoonotic potential of brucellosis has historically been a major factor in the control and eventual eradication of brucellosis in animals. Cases of human brucellosis caused by B. abortus have declined with reduced prevalence of the disease in livestock and with pasteurization of milk. Prior to the onset of the State/Federal Cooperative Brucellosis Control Program, the number of cases of human brucellosis reported to the Center for Disease Control reached a high of 6,321 in 1947. Presently, the number reported is approximately 100 per year; these cases are virtually all due to B. melitensis, B. suis or B. abortus.

In 1995, "The Fund for Animals, Inc." surveyed state Departments of Health for reported cases of human brucellosis. Forty-two states responded. This survey covered the time from 1980 through 1995, with a few states reporting for a shorter period and a few longer. The respondents reported 1729 cases of human brucellosis with 9 deaths. In most instances, the species of Brucella, i.e., abortus, suis, or melitensis, was not indicated. Of the 9 fatalities, 4 were miscarriages. None of the respondents identified the Brucella species. Four states commented on wildlife to human exposure.

Alaska indicated an average of 1 human case per year from 1958 to 1980 and 2 cases since then. All were attributed to contact with caribou (P. Nakamura, pers. comm.). These were probably caused by Brucella suis Biovar 4.

The Montana Department of Public Health has identified two cases in which they are confident that a patient contracted brucellosis after exposure to wildlife (T. Damrow pers. comm.). In 1995, a 40-year old man from Yellowstone County, Montana was diagnosed with brucellosis. The diagnosis was based on serology and clinical signs. He had been exposed to an elk bull calf which he shot and field dressed in 1991. Neither the elk carcass nor the viscera were tested for B. abortus. He also helped load a cow elk that a friend shot but was not present when the elk was shot. There was no other work or travel history suggesting an exposure risk. The bull calf was the only significant risk factor in this case (Murphy 1995; T. Damrow, pers. comm.). In 1986, a 39-year old rancher from Madison County, Montana was diagnosed with brucellosis. His 250 cattle had all been vaccinated against brucellosis and tested serologically negative after the rancher’s diagnosis. He had, however, helped field dress three elk from the Jack Creek and Bear Creek areas of the Madison Range (T. Damrow, pers. comm.). B. abortus has been cultured from Jack Creek elk, and approximately half the elk wintering in the Bear Creek area migrate from Yellowstone National Park (K. Aune, pers. comm.). Two of the elk were females and one was reportedly pregnant. The elk were the suspected source of the rancher’s infection (T. Damrow, pers. comm.). There were no positive Brucella cultures in either of these cases.

Florida Department of Health and Rehabilitative Services indicated human disease from exposure to wild hogs (W. Bigler, pers. comm). These were probably caused by Brucella suis.

Texas reported 2 human cases in 1991 following exposure to wild hogs (Bureau of Communicable Disease Control 1992). These were probably caused by Brucella suis.

It has been stated that the risk of wildlife brucellosis, caused by B. abortus, as a source of disease for humans appears to be slight (Young and Nicoletti 1997). However a risk does exist. In addition to the risk of direct exposure, there is also a risk of indirect exposure via transmission to domestic animals then to humans. There are currently no data to estimate how the risk of indirect exposure via domestic animals compares to the risk of direct exposure to brucellosis from infected wildlife.

References:

[INDEX]

BRUCELLOSIS CLASSIFICATION AND EPIDEMIOLOGY IN LIVESTOCK HERDS

"In 1956, Congress authorized the Secretary of Agriculture to enter into cooperative agreements with individual states for a brucellosis eradication program based on the Recommended Brucellosis Eradication Uniform Methods and Rules" (Greater Yellowstone Interagency Brucellosis Committee 1997). According to the UM&R, a cattle herd or captive bison herd may be classified as a brucellosis reactor herd based on test data. A herd is classified an affected herd after B. abortus has been isolated from at least one animal in a suspect and/or reactor herd, or epidemiological data such as official serological tests and herd history support that conclusion. An affected herd is one in which one or more animals have been determined to be infected (Greater Yellowstone Interagency Brucellosis Committee 1997).

Once a herd has been classified as a brucellosis reactor and/or affected herd, it is essential that epidemiological principles be applied to determine the source of B. abortus in the herd, or if the herd was the source of B. abortus for another herd(s). The epidemiological principles applied address the prevalence and incidence of brucellosis in cattle and captive bison in the area(s) or State(s) where the index herd is located, herd history, herd management, and the status of herds that may have been exposed. Under the UM&R, all herds that may have been exposed to an index herd must be tested to determine their status (Armstrong 1991, United States Department of Agriculture 1992).

References:

[INDEX]

WILDLIFE TO DOMESTIC CATTLE TRANSMISSION

Regulatory officials have concluded that wild elk or bison were the probable source of B. abortus infection for cattle on six Wyoming premises in the GYA. Based on the epidemiology, it was concluded that the most probable source for four of the premises was elk, and, on the remaining two, elk or bison. Five of the premises were located west of the continental divide and one east of the continental divide. The conclusion that wildlife was the source of these infections is disputed by some. However, extensive epidemiological evidence, including complete testing of herds associated with the affected premises, ruled out domestic livestock as the source. Two of these instances have occurred since Wyoming was classified as brucellosis-free in 1985. Brucellosis on the last affected premises, located east of the continental divide, required the testing of approximately 5000 head of cattle in the eight herds epidemiologically associated with it. There was no evidence of infection in any of the eight herds. Regulatory officials concluded that the source of infection for this herd was either elk or bison. Ongoing surveillance and testing of cattle herds in the GYA revealed no additional affected premises. These findings support the conclusion that the cattle were not the source of B. abortus in any of the six affected premises.

Following are case descriptions (I through VI) for the brucellosis-affected cattle herds on these six premises. They are based upon USDA, APHIS, Veterinary Services and Wyoming Livestock Board epidemiologic investigations.

I. Beef cattle herd:

A.Location: Alpine Junction, Wyoming

B.County: Lincoln

C. Most probable source: Fence line contact with Alpine Feedground. Drainage from the feedground ran through the area where the producer fed his cattle during the winter.

D. detected: Early 1960's and 1970's

E. B.abortus Biovar I isolated: yes no unknown

F. Quarantined: February 28, 1969

G. Quarantine released last time: December 15, 1977

This herd was infected in the early 1960's. The herd was tested free of brucellosis and the quarantine was released. At that time wildlife (elk) was considered a possible source of infection for this herd. The owner kept good records on his operation. Brucellosis was found in the herd again eight (8) years later. Epidemiology and testing of all herds associated with this herd revealed no other affected herds. It was concluded that the most probable source was elk.

Since this was the first time wildlife was suspected, all of the above information was given to the Wyoming Game and Fish Department. Prior to 1969 they believed that there was no brucellosis in any of the 22 Wyoming elk winter feedgrounds. The National Elk Refuge was the only feedground with elk known to be affected with brucellosis. However, subsequent testing of state feedgrounds revealed brucella titers in elk on most of the those feedgrounds.

The Wyoming Game and Fish Department began testing feedground elk with the Alpine (Greys River) Feedground located in Lincoln county. These tests were conducted in 1971, 1973, 1974 and 1976, prior to vaccination of the herd with Strain 19 vaccine. Of 203 adult female elk, 46% (94) were classified as seropositive (Wyoming Game and Fish Department, unpublished data). The Wyoming Game and Fish Department subsequently instituted a research program on transmission studies of brucellosis from elk to cattle. The research program included B. abortus Strain 19 vaccination trials that were conducted at the Research Department in Sybille, Wyoming and funded in part by USDA, APHIS, Veterinary Services. Vaccination was initiated on the Alpine feedground and eventually expanded to include additional elk winter feedgrounds.

Personal Communication References for this case:

[INDEX]

II. Beef cattle and captive bison herd unit:

A. Location: Bondurant, Wyoming (upper Hoback River)

B. County: Sublette

C. Most probable source: Elk to bison and cattle - Elk commingling in the winter with owner's cattle and bison herds where they were fed on the ground

D. Detected: March 1982

E. B. abortus Biovar I isolated: yes no unknown

F. Quarantined: March 29, 1982

G. Quarantine released: August 24, 1983

The second affected premises involved privately-owned bison and cattle herds both affected with brucellosis. Since they were present on the same premises, they were considered one herd. It was located on the upper Hoback River in Bondurant, Wyoming. A great deal of detailed work and surrounding testing of contact herds was done to epidemiologically document the source of infection for this herd.

The herd history begins with the rancher calling a local veterinarian, from Pinedale, out to his place on March 16, 1982, since two (2) cows (cattle) had just aborted. The veterinarian collected blood samples from both cows, plus an aborted fetus, and submitted them to the Wyoming Diagnostic Laboratory, Laramie, WY. The serology was classified as a reactor. Also, Brucella abortus, Biovar I, was isolated from the aborted fetus.

There was no history of any cattle purchases for a number of years, according to the owner. This was verified when the Wyoming Livestock Board, i.e., the State Veterinarian's records of import permits being issued were reviewed; the local brand inspectors records were reviewed, and the neighbors were contacted. The herd files in the Cheyenne Federal office indicated that several partial herd tests of this herd had been conducted going back to 1973. The tests were conducted by a local veterinarian for sales, shows, and/or milk ordinance requirements. All tests were negative for brucellosis.

On January 16, 1980, under an agreement between the State and Resident Landowners, who met certain requirements and were interested in developing their own private bison herd, the owner obtained three (3) brucella-vaccinated, yearling bison females, and three (3) yearling bison males. Their source was the State of Wyoming owned brucellosis-negative bison herd, located at the Thermopolis State Park. These six (6) head were the seed stock for the bison portion of this herd.

The beef herd ran in the Hoback Grazing Association, with ten (10) other cattle herds, during the summer grazing period; and the bison stayed on the owner's privately-owned land. There were two additional cow herds which had fence contact with this herd that were not associated with the Grazing Association.

The affected herd had forty-eight (48) cows (with approximately one-half (½) the herd officially calfhood vaccinated for brucellosis) two (2) bulls, twelve (12) non-vaccinated heifers born the previous year, and fifteen (15) bison (calfhood vaccinated).

This herd was considered to have been recently infected because retests of the herd continued to show an increase in prevalence. Eventually, 94% of the animals were classified as reactors and Biovar I was also isolated from the bison segment of the herd.

Following are the summarized brucellosis herd test results for the cattle and bison herds.

Cattle herd test results:

A. Herd test results of forty eight (48) test eligible cows

1. 3/16/82: 2 cows classified as reactors and shipped to slaughter.

2. 3/29/82: 46 cows with 11 classified as reactors and shipped to slaughter.

B. 4/9/82: 12 Yearling heifers with 5 classified as reactors.

C. 6/7/82: Complete herd test - 49 tested & 45 classified as reactors

1. 35 cows: 33 were classified as reactors and shipped to slaughter

2. 2 bulls: 1 was classified as a reactor and shipped to slaughter

3. 12 yearling heifers: 11 classified as reactors - all spayed and fed out in a quarantined feedlot

D. Herd balance: Two (2) cows and one (1) bull which were tested monthly through August 17, 1983 and remained negative.

Bison herd test results:

A. October 4, 1982:Complete herd test - 15 (Yearling to 3 ½ yrs.) & 15 classified as reactors

B. B. abortus, Biovar I was isolated

During the late fall and early winter of 1982, the ten (10) Grazing Association Herds (cattle) were tested revealing one (1) reactor animal in a herd, and one (1) suspect animal in another herd. The suspect was retested negative. The reactor was a 1981 import from another state, kept at the home place outside of Pinedale, and was never on the Hoback Grazing Association. The herd with the one reactor, following its removal, was retested four additional times with no additional evidence of infection. A total of four thousand seven hundred twenty-two (4,722) head of cattle from the 10 grazing association herds tested negative. The two (2) fence contact herds were also tested negative consisting of an additional one hundred forty-four (144) negative head of cattle.

The bison herd in the Hot Springs State Park was tested negative reconfirming its previous negative status.

During the winter of 1981-82, the snow was over four feet on the level in the Bondurant area. The affected cattle and bison herd segments were kept separate from each other, and each were concentrated in small areas and fed on the ground; and, according to the owner as well as neighbors, there were elk co-mingling with both his bison herd and cattle herd that winter.

It is very probable, based on the epidemiological evidence (herd history, prevalence rates, and lack of secondary spread to other herds in the area) that the B. abortus was introduced into this herd during the winter of 1981-1982.

The test negative contact herds, 12 herds with 4,866 head of cattle, were eliminated as a source of B. abortus Biovar I for this herd. In addition, the APHIS Market Cattle Surveillance program, which includes bison, requires all herds to be sampled at slaughter and/or livestock markets each year, has not revealed another affected herd. To date, this area has remained free of B. abortus for over fourteen (14) years, except in free ranging wildlife. It is a known fact that elk infected with B. abortus can abort, which has been observed during the winter on several elk feedgrounds, including the National Elk Refuge in Jackson. It is also known through feedground sampling that the elk in this part of Wyoming are infected with B. abortus. This supports a conclusion that the elk were the most probable source.

The Wyoming Game and Fish Department, however, did expand their sampling to more feedgrounds for evidence of brucellosis and found positive animals in most feedgrounds sampled. Today it is accepted by Wyoming Game and Fish Department that B. abortus exists in all state feedgrounds, and they continue to vaccinate elk at 21 of 22 state feedgrounds.

Reference for this case:

Personal Communication References for this case:

[INDEX]

III. Beef cattle herd:

A. Location: Cora, Wyoming

B. County: Sublette

C. Most probable source: Black Butte Elk Feedground located within the outer boundaries of the ranch premises

D. Detected: November 1983

E. B. abortus Biovar I Isolated: yes no unknown

F. Quarantined: December 1, 1983

G. Quarantine released: January 28, 1985

Brucellosis was detected in November, 1983, in the Cora, Wyoming, Area (Sublette County). The Black Butte Elk Feedground lies within the outer borders of this ranch. Again, extensive epidemiology and all possible contact herds were tested, with no source of infection determined, except diseased wildlife. Again, as of today, there has been no evidence of livestock infection in this entire county. Absolute proof of infection in this herd was verified through culturing of the brucella organism in the laboratory.

This herd was comprised of over three hundred (300) test eligible cattle. Six (6) contact herds were tested with no evidence of infection. With testing and removal of reactors, the infection was eliminated from this herd.

Personal Communication References for this case:

[INDEX]

IV. Beef cattle herd:

A. Location: Jackson, Wyoming

B. County: Teton

C. Most probable source: Extensive migration of elk and bison through this property

D. Detected: 9;November 1984

E. B. abortus Biovar I Isolated: yes no unknown

F. Quarantined: November 5, 1984

G. Quarantine released: November 25, 1985

Brucellosis was detected in Teton County, November, 1984, in a herd of twenty-two (22) test eligible cattle with seven (7) serologic reactors. Two contact herds were tested with no evidence of infection. With testing and removal of reactors, the infection was eliminated from this herd. The brucella organism was not recovered on culture attempt. The owners stated that elk and bison migrate extensively back and forth through their property. Again, no source other than wildlife could be found.

Personal Communication References for this case:

[INDEX]

V. Beef cattle herd (not affected) and dairy cattle herd (affected):

A. Location: Etna, Wyoming

B. County: Lincoln

C. Most probable source: Elk frequented the premises and would feed with the dairy cattle herd in their feed bunk

D. Detected: October 1985

E. B. abortus Biovar I Isolated: yes no unknown

F. Quarantined: November 8, 1985

G. Quarantine released: November 5, 1986

This case involves a producer in Star Valley (Lincoln County) that had a dairy herd and a small beef herd. Through the routine milk testing program, known as the Brucellosis Ring Test (BRT), a positive was detected October, 1985. The dairy herd revealed two (2) reactors on testing, and the beef herd was negative. This producer raised his own replacements and had only purchased a bull over the past ten (10) years. The Idaho State Laboratory cultured B. abortus from tissue samples submitted. Four associated herds were tested with no infection disclosed.

The owner reported that elk frequented his property and were known to eat out of his dairy cattle feed bunks. Again, no source other than wildlife could be found.

Personal Communication References for this case:

[INDEX]

VI. Parker Land and Cattle Company - Beef cattle herd:

A. Location: Dubois, Wyoming

B. County: Fremont

C. Most probable source: Elk or bison

D. Detected: February 1989

E. B. abortus Biovar I Isolated: yes no unknown

F. Quarantined: February 27, 1989

G. Quarantined released: June 1, 1989

The isolation of biovar I from several seropositive cattle in a herd near Dubois, Wyoming confirmed that the herd was affected with brucellosis. The owner elected to send the entire herd to slaughter.

The herd was primarily a closed herd except for 25 bred heifers that were added in 1984 and bulls that were added since 1984. The heifers were traced to their herds of origin in Wyoming and Montana and found not to represent a possible source of the disease. The bulls were purchased from purebred herds with no history of brucellosis.

Of 45 brucellosis reactors found on the first complete herd test, 62.22% were determined to be not officially calfhood vaccinated and ranged in age from 5 to 10 years. Also, out of 38 brucellosis reactors found on the second complete herd test, 89.47% were determined to not be officially calfhood vaccinated and ranged from 5 to 10 years of age. The testing of 5000 head of cattle in eight (8) herds epidemiologically associated with this herd revealed no evidence of infection in any of them.

A review of the USDA Log For Market Cattle Test reactors (VS Form 4-100) from January 1983 through March 1989 revealed no MCI Reactors for any of the eight epidemiologically-associated herds, or any other herds, except the Parker Land and Cattle Company herd. Only two Parker Land and Cattle Company MCI reactors were revealed which led to the herd being found to be affected.

Bison and elk had been in areas used by Parker cattle (Bridgewater 1989). There was a bull bison sighting in one of Parker’s allotments and several bison sightings on an adjacent allotment during late July and early August of 1988. It is unknown whether there was any commingling with cattle. The closest bison herd, the Jackson herd, was known to be affected with brucellosis. The Parker herd and other cattle herds shared spring, summer and fall pasture with elk from the Wind River Herd Unit. The Wind River Elk Herd Unit did not use a feedground and had not been tested for brucellosis.

It was concluded that elk or bison were a possible source of brucellosis in the Parker Land and Cattle Company herd. This is the only premises in which the owner pursued legal action. Ongoing surveillance and testing of cattle in the GYA has revealed no additional affected premises.

References for this case:

Additional premises where the transmission of B. abortus is addressed in captive wildlife and domestic (cattle) can be found in the Appendix.

[INDEX]

WILDLIFE TO HORSE TRANSMISSION

One case of brucellosis transmission from elk to a horse has occurred on a state feedground in Wyoming (Greater Yellowstone Interagency Brucellosis Committee 1997). Following is a summary of that case.

A. Location: Wintered on South Park Elk Feedground for two winters prior to developing fistulous withers.

B. County: Teton

C. Most probable source: Based on the history and epidemiology of this mare, it was concluded that the most probable source was infected elk from the affected elk herd unit on the South Park Elk Feedground. The mare commingled and fed with the wild, free-ranging elk on this feedground.

D. Detected: October 17, 1996

E. B. abortus Biovar I Isolated: yes no unknown

F. Quarantined: October 28, 1996

G. Quarantine released: June 13, 1997. The mare foaled a colt on June 3, 1997 and was put down on June 12, 1997.

Reference for this case:

Personal Communication Reference for this case:

[INDEX]

WILDLIFE to WILDLIFE TRANSMISSION

Natural infections with brucellosis have occurred in moose (Alces alces) with two cases described in the U.S. (Fenstermacher and Olsen 1942, Jellison et al. 1953) and two cases in Canada (Corner and Connell 1958). Based on epidemiology, the most probable source of B. abortus infection in elk and moose in Canada was affected bison from Elk Island, a fenced game preserve in Canada (Corner and Connell 1958). Fenstermacher and Olsen (1942) could only surmise how a moose in Minnesota became infected with B. abortus. They consider contact with cattle as one possibility. Jellison et al. (1953) did not speculate on the origin of brucellosis in a female moose in Montana. Brucellosis in moose apparently differs from the disease in other animals by producing a generalized and apparently fatal disease, and the rare occurrence of positive serologic reactions to brucellosis in moose may well be due to its usual fatal termination.

References:

[INDEX]

EXPERIMENTAL TRANSMISSION

BISON

AT Texas A&M University, under confined conditions, it was demonstrated that bison inoculated with B. abortus strain 2308 transmitted B. abortus to susceptible cattle.

Reference:

[INDEX]

ELK

Controlled studies at the Wyoming Game and Fish Department's Sybille Wildlife Research and Conservation Education Unit demonstrated that B. abortus (strain 2308) causes abortion in elk and that under confined conditions B. abortus may be transmitted from infected elk to susceptible cattle. Although this transmission occurred under artificial confined conditions, one can conclude that these circumstances were not too unlike those when elk are fed with cattle on cattle winter feedlines.

References:

[INDEX]

APPENDIX

CAPTIVE WILDLIFE TO DOMESTIC CATTLE TRANSMISSION

NORTH DAKOTA

Beef/Dairy Bison herd unit:

A. Location:Carson, North Dakota

B. County: Grant

C. Most probable source: Captive bison

D. Detected: July 14, 1983

E. B. abortus Biovar I isolated: yes no unknown

1.Bison: Herd size - 19 head, and all were reactors. Eight of these were culture positive.

2. Cattle: Herd size - 78 head, and one was a non-vaccinated reactor. This animal tested negative with the balance of the herd on October 1982. This animal was culture positive.

F. Quarantined: July 21, 1983

G. Quarantine released: Herds depopulated 1983

Reference for this case:

[INDEX]

ARKANSAS

Beef cattle herd:

A. Location: Gentry, Arkansas

B. County: Benton

C. Most probable source: Adjacent affected Bison herd

D. Detected: January 25, 1991. It was tested because it was adjacent to a known 1988/1989 affected captive bison herd. Reactor rate:

1. Bison herd: 15/24 x 100 = 62.5%

2. Cattle herd: 3/40 x 100 = 7.5%

E. B. abortus Biovar I Isolated: yes no unknown

1. From Bison herd: yes no unknown

2. From cattle herd: yes no unknown

F. Quarantined: 1991

G. Quarantine released: 1991

Personal Communication Reference for this case:

[INDEX]

DOMESTIC CATTLE TO CAPTIVE WILDLIFE TRANSMISSION

TEXAS

Captive Bison herd:

A. History/Epidemiology

1. Closed herd

a. Originated from less than 10 head

b. Purchased from ranch in south Texas about 20 years ago

2.They have never been vaccinated for brucellosis.

3. They calve about every other year.

4. The bison are on about 1500 acres all under a game proof fence, cross game fenced using high game fence into smaller pastures.

a. There are about 600 head of elk on the premises - they tested negative for brucellosis.

b. There are also deer on the premise and other exotics on the premises.

5. The bison were rotated through the pastures as a group.

6. There has not been a standing breeding cattle herd on the premises for 5 years.

7. Portions have been leased for summer grazing of cattle.

8. Cattle have been purchased for grazing.

B. Most probable source:

1. Cattle placed on the premises for grazing.

2. Exposure from a relative’s cattle under quarantine for brucellosis that used the handling facilities on the premises.

a. This herd is located several miles away from the game farm premises.

b. They were driven across the premises for working.

C. Herd tested February 9, 1996:

1. Size of bison herd tested: Fifty eight (58) head

2. Purpose of test: Private going out of business sale.

3. Test results:

a. February 9, 1996: Three cows and 1 bull were classified as suspects and were isolated from the rest of the herd.

b. February 16, 1996: The 4 suspects were retested and cultured.

(1) Three cows were classified as reactors. Two of them had full term calves in them at slaughter, the other calved in isolation on the premises just prior to slaughter.

(2) Biovar I was isolated from two of the cows at slaughter. These cows were 10 + years of age.

D. Date of Hold Order: 2/20/96

E. Date of Quarantine: 5/13/96

F. The bison herd was cleaned up using the testing procedures spelled out in the Brucellosis Eradication UM&R. This involved test and slaughter of suspects and reactors and retest of the herd.

G. The quarantine was released 3/12/97.

Personal Communication Reference for this case:

[INDEX]

KANSAS

The following information summarizes facts and epidemiological conclusions related to brucellosis in three cattle herds and one captive bison herd in Kansas. Findings indicated that one cattle herd - the index herd - contracted brucellosis and transmitted the disease to the captive bison herd; the bison herd subsequently transmitted the disease to two additional cattle herds.

I. Index Cattle Herd

A. Brucellosis-affected cattle herd depopulated

August 31, 1995.

B. B. abortus Biovar I isolated: yes no unknown

II. Captive Bison Herd

A. Same owner as index cattle herd. Bison and cattle herds commingled.

B. Most probable source of B. abortus: The owner’s affected cattle herd commingling with the bison herd.

C. Herd History/Epidemiology

1. Source of bison herd: Maxwell game preserve, Canton, Kansas.

2. The preserve has an annual gathering where the culls are sent to slaughter.

3. A percentage (approx. 50 head) of the remaining herd are brucellosis tested.

4. There has been no record of brucellosis in the preserve herd.

5. Excess calves are sold to the public.

D. Tested for brucellosis due to commingling with affected cattle herd.

1. Size of bison herd tested:

a. Ten (10) adult females

b. Six (6) adult males

c. Two (2) yearling females

d. Three (3) yearling males

2. Test dates: April 19-22, 1996

3. Serological test results: 5 Reactors (2 adult females, 3 adult males)

4. B. abortus Biovar I Isolated: Yes

E. Quarantined August 9, 1995, at the same time that the owner’s affected cattle herd was quarantined.

F. Disposition

1. Quarantine released: October 8, 1996

2. The bison were purchased by USDA, APHIS, VS for research purposes. They were shipped to Texas A&M University on September 30, 1996 and used for RB51 research.

III. Two Other Cattle Herds

A. Both cattle herds were adjacent to the affected bison herd.

B. Based on the herd history and epidemiology, the most probable source of brucellosis in two other cattle herds was the brucellosis-affected bison herd.

C. Both cattle herds were tested as adjacent contact herds and tested serologically negative sixty-nine plus (69+) days after the index cattle herd was depopulated.

D. B. abortus Biovar I was isolated from one of these cattle herds. Tissues for culture were not obtained from the other herd.

Personal Communication Reference for this case:

[INDEX]

PERSONAL COMMUNICATION REFERENCES

  1. Keith Aune
    Supervisor
    Wildlife Disease Laboratory
    Montana Department of Fish, Wildlife and Parks
    1400 S. 19th St.
    Bozeman, MT 59717

  2. William J. Bigler
    Biological Scientist
    State of Florida
    Department of Health and Rehabilitative Service
    1317 Winewood Boulevard
    Tallahassee, Florida 32399-0700

  3. A. Russell Burgess, D.V.M.
    Area Veterinarian In Charge
    USDA, APHIS, VS, Wyoming
    Past Asst. State Veterinarian
    Wyoming Livestock Board

  4. M. E. Coats Jr., D.V.M., M.S.
    Epidemiologist
    Texas Animal Health Commission

  5. Terry H. Conger, D.V.M., Ph.D.
    Brigham Young University, UT
    Past Station Epidemiologist
    USDA, APHIS, VS, Arkansas
    Past State Epidemiologist
    Arkansas Livestock & Poultry Commission

  6. Todd Damrow, Ph.D.
    Montana State Epidemiologist
    Montana Department of Public Health
    Cogswell Building
    Helena, Montana 59620

  7. Donald E. Evans, D.V.M., M.S.
    Area Epidemiological Officer
    USDA, APHIS, VS, Kansas

  8. Peter Nakamura
    Director
    Division of Public Health
    Department of Health and Social Services
    P.O. Box 110610
    Juneau, Alaska 99811-0610

  9. L. Mark Stewart, B.S., D.V.M., M.P.V.M.
    Area Epidemiological Officer
    USDA, APHIS, VS, Wyoming

  10. Norman R. Swanson, B.S., D.V.M.
    Private Practice in Wyoming
    Past State Veterinarian
    Wyoming Livestock Board

  11. Douglas A. Woody, D.V.M.
    Veterinary Medical Officer
    USDA, APHIS, VS, Wyoming

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