• Capture, Test, and Slaughter. All buffalo that test positive are sent to slaughter, including bulls, even though transmission is thought to occur primarily (or only) when an infected female gives birth or aborts. In spring of 2002, when the Yellowstone buffalo population exceeded an arbitrary population “cap” of 3,000, MDOL sent more than 100 buffalo to slaughter without even testing them first. In 2003, the National Park Service—the agency responsible for protecting the buffalo and other Park wildlife—sent more than 200 buffalo to slaughter before any disease testing was conducted on these individuals.

The Yellowstone Bison  
    Brucellosis Myth

The Montana Department of Livestock (DOL) claims it is slaughtering the Yellowstone bison because they carry brucellosis. This claim rings hollow in light of a few facts: There has never been a documented transmission of brucellosis from wild bison to livestock. Even if buffalo were capable of spreading the disease, there are no cattle on these lands from mid-October to mid-June, making brucellosis transmission impossible.

All bison captured and slaughtered this winter have been bulls, which are incapable of transmitting the disease. The ten bull bison slaughtered this week tested positive for brucellosis antibodies, not infection. Because bison are known to build natural resistance to brucellosis, these animals may actually be the strongest, healthiest animals of the herd. The overwhelming majority of bison slaughtered according to these test results don't actually carry the disease.

Most bison that test positive at the capture facility test negative under the more accurate post-slaughter necropsy. The DOL is using a new methodology for detecting antibodies to brucellosis in wild bison called the Fluorescent Polarization Assay (FPA). This testing method involves the use of antigens tagged with a fluorescent material which detect IgG (immunoglobulin G) type antibodies to brucellosis and bind with them. Binding between the antibody and the tagged antigen results in an increase in polarization which is detected by the analyzer and reported as a quantitative result. This result is interpreted as positive or negative based on certain cut-off values. Studies have established that the specificity and sensitivity of this test were found to be much higher when compared to Particle Concentration Fluorescence Immunoassay and the CARD test (Nielsen et al 1998).

However, in spite of the advanced technology of this testing method it is only capable of detecting IgG (long term immunity) antibodies, not the presence of brucella organisms. The major advantage of FPA over the Card test is that it will detect a quantitative level of antibodies, which may or may not directly correlate to the presence of an infection, whereas the Card test simply detects the qualitative presence or absence of antibodies. Although the DOL has finally begun using advanced technology to detect brucellosis antibodies in wild bison, they are still unable to correlate their test results to prove actual infection.

Culture of tissues from slaughtered bison are no longer being done to confirm their testing results. In spite of these facts, DOL continues to use the results of both the FPA and the Card test to send low risk bison (i.e. bulls) to slaughter.

Even if only the Card test is positive and the more specific FPA is negative, a buffalo will be sent to slaughter. Why is DOL spending thousands of tax payer's dollars on new technology if it will not be properly utilized and potentially save uninfected bison from needless slaughter?

Sources;
Nielsen, K., Gall, D., Lin, M., Massangill, C., Samartino, L., Perez, B., Coats, M., Hennager, S., Dajer, A., Nicoletti, P., Thomas, F. 1998. Diagnosis of bovine brucellosis using a homogeneous fluorescence polarization assay. Veterinary Immunology and Immunopathology. 66(1998) 321-329.
Perkin/Elmer Life Sciences, web site. Accessed 01/10/02.
Lumigen web site. Accessed 01/10/02. USAHA web site information from 1997.

Brucellosis in Wild Bison
   Fact  Sheet

Summary: Brucellosis was first detected in the Yellowstone Buffalo herd in 1917. The buffalo were exposed to brucellosis by domestic cattle that were grazed in the park and held in confinement with buffalo. Brucellosis is most commonly transmitted among and between species through ingestion of infected birthing materials. Yellowstone buffalo developed a natural immune response to brucellosis and do not typically suffer from the disease. It is believed that many buffalo may also have a genetic immunity to brucellosis. Failed pregnancies, the most common symptom of brucellosis, are relatively unknown in Yellowstone buffalo. The most likely mode of exposure among buffalo is ingestion of small amounts of bacteria from newborn live calves. Essentially, the buffalo in Yellowstone are vaccinating themselves for brucellosis, developing an immune response, and clearing the bacteria. There has never been a documented case of brucellosis transmission between buffalo and domestic cattle under natural conditions. In Grand Teton National Park, where vaccinated cattle and brucellosis exposed buffalo have been commingling for decades, no transmission has ever occurred. The chances of transmission between wild buffalo and vaccinated domestic cattle have been characterized as “very low”.

Issues: A number of factors including the incidence and transmitability of brucellosis in buffalo, the distribution of cattle in the Greater Yellowstone Area, and the regulatory structure in place for brucellosis relate to the current situation that has led to the death of nearly 4,000 buffalo since 1985.

1. Testing methods: There are currently two methods to test buffalo for brucellosis exposure and infection; serology and culture. Serologic testing involves drawing blood from live animals to determine if long-term antibodies for brucellosis are present. Buffalo that test positive are considered infected and sent to slaughter. Approximately 45 percent of Yellowstone buffalo test sero-positive on the CARD test, the one most commonly used by the agencies. Culture testing involves tissue sampling from slaughtered buffalo to determine if actual bacteria are present. Culture testing is considered to be the “gold standard” in determining infection. Drastic differences between sero-positive and culture positive buffalo indicate that many buffalo are being slaughtered simply because they have developed immunity to brucellosis and are not actually infected. A combination of test results indicate that only between 2 and 20 percent of buffalo actually have brucellosis bacteria in their bodies at any given time.

2. Transmitability: The most likely method of transmission between species is ingestion of infected birthing materials from an aborted fetus. Buffalo bulls, calves, yearlings and non-pregnant females do not pose a significant risk of shedding infected materials in the environment. When a female buffalo is infected with brucellosis, she will pass the bacteria in her first pregnancy. After the first calving, the uterus will “superprotect” itself from brucellosis preventing infected material from being shed in subsequent calving even if she is re-exposed. Therefore, only pregnant female buffalo in the first calving cycle after exposure have the possibility of shedding infected material in the environment. Brucellosis related abortions, even among infected females, are extremely rare in Yellowstone buffalo. Given the very small segment of the population that can even potentially transmit brucellosis combined with the low probability of transmission occurring in natural settings, the real chances of brucellosis transmission are extremely low. Additionally, brucellosis bacteria will not survive in warm weather and direct exposure to sunlight, and the activity of predators/scavengers all but guarantee that fetuses or infected birthing material will not persist in the environment beyond mid-May.

3. Distribution of Cattle: Relatively few cattle graze in the GYA at any time of the year, particularly in the winter and spring months when transmission is even a possibility. In the Western Boundary Area, no cattle are present within 45 miles of Yellowstone National Park in winter and spring. Cattle are typically only in the area between mid-June and mid-October, a period when there is no possibility of brucellosis transmission. The vast majority of cattle that graze in the summer in the Western Boundary Area are imported from Idaho and are already subjected to brucellosis vaccination and testing. In the Northern Boundary Area, The Church Universal and Triumphant grazes cattle on private land west of the Yellowstone River in the winter and spring months. CUT also maintains the rights to graze cattle on the Devil’s Slide federal allotment. These are the only cattle on the west side of the Yellowstone River between Gardiner and Yankee Jim Canyon. One producer grazes about 25 cows on the east side of the Yellowstone River approximately 4 miles north of Gardiner on Rt. 89. This same producer brings his cattle to private land adjacent to the Eagle Creek Special Management Area in the spring months. Untested buffalo are allowed to be in the Eagle Creek SMA as well and no transmission of brucellosis has ever occurred. One additional producer grazes cattle on the east side of Yellowstone River north of Gardiner.

4. Regulatory issues: Montana is currently certified brucellosis class free. Class free status allows producers to transport reproductive cattle across state lines without brucellosis testing. The United States is not certified brucellosis free by the OIE, the international regulatory body. Therefore, brucellosis testing is required to transport reproductive cattle across international boundaries. In order for the US to be certified brucellosis free by the OIE, no livestock in the country can have been vaccinated for three years.

Conclusion: Only a relatively small percentage of Yellowstone buffalo are actually infected with brucellosis. Brucellosis does not have any significant impact on the health of the Yellowstone buffalo. The risk of transmission between wild buffalo and cattle is extremely low. Relatively few susceptible cattle graze in the GYA and most are not present when transmission is even a possibility. Herd management plans that adjust stocking dates could be developed to insure that transmission does not occur. Montana can easily comply with the National Brucellosis Eradication Program to insure that brucellosis class free status is preserved. The GYA could be exempted from the OIE certification process and allow the rest of the county to enjoy international brucellosis free status. Montana can develop risk management strategies for domestic cattle to allow for wild, free roaming population of buffalo in GYA and beyond.

THIS INFORMATION WAS OBTAINED FROM THE BUFFALO FIELD CAMPAIGN.