Brucellosis Laws in Illinois: What Cattle and Bison Owners Need to Know
August 10, 2026
Brucellosis is one of the most closely regulated livestock diseases in the United States, and Illinois has built a robust legal framework around preventing its return. If you own cattle, bison, or swine in Illinois — or if you move animals across state lines — understanding the state’s brucellosis rules is not optional. A single compliance gap can trigger quarantines, fines, and the loss of your herd’s disease-free certification.
This guide walks you through every layer of Illinois brucellosis law, from the state’s current classification status to vaccination rules, testing protocols, movement requirements, and the penalties you face for violations. Whether you are a longtime livestock producer or new to Illinois agriculture, these regulations apply to you.
What Is Brucellosis and Why It Is Regulated in Illinois
Brucellosis — also known as contagious abortion or Bang’s disease — is a costly disease of livestock and wildlife caused by a group of bacteria in the genus Brucella. The disease has significant consequences for animal health, public health, and international trade, and it occurs mainly in cattle, bison, and swine, but can also affect cervids, goats, sheep, horses, and people.
Brucellosis is a contagious bacterial disease that may cause pregnant females to abort and animals of both sexes to become infertile. It does not contaminate the meat from infected animals, but it may reduce milk yields in infected dairy cows. From a public health standpoint, the risk is equally serious.
Brucellosis is zoonotic, meaning it can be transmitted from animals to humans through contact with bodily fluids and infected tissues. It can be avoided by proper sanitation and herd management. There is no cure for brucellosis. Animals may recover, but they often remain infected and capable of spreading the disease.
In 1954, Congressional funds were approved for a Cooperative State-Federal Brucellosis Eradication Program, which has been successful in the eradication of bovine brucellosis in domestic cattle and bison in the U.S., with the exception of the Greater Yellowstone Area. Illinois participates fully in this program through the Illinois Bovine Brucellosis Eradication Act (510 ILCS 30) and its associated administrative regulations found at 8 Ill. Adm. Code Part 75.
If you are also researching other animal health and ownership rules in the state, you may find it helpful to review pet import laws in Illinois or explore beekeeping laws in Illinois for related agricultural compliance topics.
Illinois’s Brucellosis Classification Status
Illinois has maintained bovine brucellosis-free status since 1992 and swine brucellosis-free status since 1984, enabling the state to repeal some industry testing requirements. This long-standing record places Illinois firmly in the highest tier of the federal classification system.
Under the USDA’s Brucellosis Eradication Uniform Methods and Rules (UM&R), states are assigned one of four classifications: Class Free, Class A, Class B, or Class C. States or areas that do not meet the minimum standards for Class C status are required to be placed under federal quarantine. Restrictions on moving cattle and bison interstate become less stringent as a state or area approaches or achieves Class Free status.
For initial classification or reclassification as Class Free, all cattle herds in the state or area must have remained free of Brucella abortus for 12 consecutive months, based on surveillance and epidemiologic investigations, and the state must have a cattle herd infection rate of 0.0 percent, or 0 herds per 1,000.
Illinois is listed among the validated brucellosis-free states under 9 CFR 78.43, alongside all other U.S. states and territories. This federal designation means that cattle and bison moving out of Illinois face fewer restrictions than animals from lower-classified states, and it provides Illinois producers with a significant trade advantage.
All 50 states, Puerto Rico, and the U.S. Virgin Islands are brucellosis-free, except for the occasional spillover of cases occurring in livestock near the Greater Yellowstone Area due to bison and elk having the disease. Illinois, located far from that region, does not face the same wildlife-driven spillover risk as western states, but the state still maintains active surveillance to protect its status.
To see how neighboring states handle their own brucellosis frameworks, you can compare brucellosis laws in Missouri or review brucellosis laws in Nebraska.
Vaccination Requirements in Illinois
Because Illinois holds Class Free status, the state’s vaccination landscape is significantly less burdensome than in lower-classified states. However, vaccination rules still exist and remain part of the regulatory framework under 8 Ill. Adm. Code Part 75.
Illinois Administrative Code Part 75 includes a specific section — Section 75.210 — dedicated to official calfhood vaccination. The Illinois Department of Agriculture’s brucellosis regulations address official calfhood vaccination as a recognized component of the state’s brucellosis program, operating under the authority of the Illinois Bovine Brucellosis Eradication Act (510 ILCS 30).
Under the federal UM&R framework that Illinois follows, official calfhood vaccination (OCV) is the standard method for vaccinating cattle against brucellosis. Key points about vaccination in Illinois include:
- Vaccination must be administered by or under the supervision of an accredited veterinarian to qualify as an official calfhood vaccination.
- Vaccinated animals must be officially identified with a USDA-approved ear tag and a tattoo in the right ear to indicate vaccinate status.
- Female calves are typically vaccinated between 4 and 12 months of age to receive official vaccinate status.
- The Certified Brucellosis-Free Herd status is valid for 12 months unless evidence of brucellosis is disclosed or the herd participates in a whole-herd vaccination plan. In the latter case, herd status is suspended until post-vaccination testing is complete.
Purebred or crossbred animals registered with an approved registry association may be identified for test or vaccination by registration number, microchip, or registry association-approved individual tattoo. This provides some flexibility for registered breed operations while still maintaining traceability.
It is also worth noting that swine brucellosis vaccination rules fall under a separate statute — the Illinois Swine Brucellosis Eradication Act (510 ILCS 95). Since Illinois has maintained swine brucellosis-free status since 1984, mandatory vaccination requirements for swine have largely been repealed, though the act remains in force as the legal authority for any future response measures.
Testing Requirements for Cattle and Bison in Illinois
Illinois’s Class Free status has allowed the state to scale back many of the routine testing requirements that apply in lower-classified states, but testing has not been eliminated. The Illinois Department of Agriculture maintains a targeted surveillance program to protect the state’s disease-free standing.
As a surveillance measure, the Illinois Department of Agriculture tests for brucellosis at slaughter facilities. Cattle sold through auction markets may also be subject to testing to ensure they are free of the disease before being introduced into a new herd.
The Market Cattle Identification (MCI) Program is the brucellosis testing program for market cattle and is part of the National Brucellosis Eradication Program (9 CFR 78). In accordance with the Illinois Bovine Brucellosis Eradication Act (510 ILCS 30/2), the Department has entered into a cooperative agreement with the USDA to identify brucellosis-infected herds.
| Testing Scenario | Requirement | Who Oversees It |
|---|---|---|
| Slaughter surveillance | Mandatory sampling at recognized slaughter facilities | ISDA / USDA APHIS |
| Auction market cattle | May be subject to testing before entering a new herd | Illinois Department of Agriculture |
| Dairy herd surveillance | Milk ELISA or ring test may be used for herd-level screening | ISDA / accredited laboratory |
| Herd additions (non-certified) | Negative official test within 60 days prior to addition, then isolation and retest | Accredited veterinarian / ISDA |
| Interstate imports (dairy/breeding) | Negative test within 30 days prior to entry required | State of origin / ISDA |
Animals originating from herds not certified may be added to a certified herd, provided they test negative to an official brucellosis test within 60 days prior to addition, are held in isolation from other members of the certified herd for a minimum period of 30 days, and are retested and negative at the end of this isolation period. Purchased additions shall not receive new herd status for sale or exhibition purposes until they have been members of the herd for at least 30 days and are included in a complete herd retest.
Approved laboratories include animal disease laboratories operated by the Department, the State-Federal Serology Laboratory, the Laboratories of Veterinary Diagnostic Medicine at the College of Veterinary Medicine, University of Illinois, or a laboratory approved by the Animal Health Official of the exporting state to conduct official tests.
All livestock, except purebred or crossbred animals registered with an approved registry association, that are tested for brucellosis and/or tuberculosis in the State of Illinois shall be identified by an official ear tag as defined at 9 CFR 78.1 (2017).
Interstate and Intrastate Movement Rules in Illinois
Movement rules are among the most practically important aspects of brucellosis law for Illinois producers. Whether you are buying cattle from another state or selling animals within Illinois, specific documentation and testing requirements apply depending on the origin state’s classification and the purpose of the movement.
Interstate Movement Into Illinois
No dairy or breeding cattle more than 6 months of age shall be imported into the State of Illinois unless they are accompanied by an official interstate health certificate showing the cattle negative to an official test for brucellosis within 30 days prior to the date of entry, except as otherwise provided in the Act. The Department may by regulation impose additional requirements on specific classes of cattle from Class B and Class C states as defined under the Brucellosis Eradication Uniform Methods and Rules approved by the U.S. Department of Agriculture.
Female cattle, except those consigned directly to slaughter or calves under 6 months of age, entering Illinois for feeding purposes from states designated by the USDA as Class B and Class C states shall, in addition to present entry requirements, be tagged in the right ear with an official ear tag identifying the cattle to the state of origin. The ear tag series shall be recorded on the official interstate health certificate or on the owner-shipper statement.
Interstate Movement Out of Illinois
Because Illinois is a Class Free state, cattle and bison moving out of Illinois to other Class Free states generally face fewer testing requirements. However, you must comply with the destination state’s entry requirements, which may be more stringent depending on that state’s rules. Always verify the receiving state’s requirements before shipping.
All official brucellosis tests of animals that are intended for interstate movement shall be made at an approved laboratory.
Intrastate Movement Within Illinois
For movement within Illinois, the primary concern involves animals moving through auction markets and livestock dealers. Auction markets and livestock dealers must submit to the Department a weekly report of the sale of all out-of-state female feeder cattle over 6 and under 18 months of age from states that are not brucellosis Class Free under the Brucellosis Eradication Uniform Methods and Rules, including the date of each sale, number sold, age, breed, and the name and address of the purchaser.
No person shall remove identification tags, numbers, brands, ear tags, microchips, or market cattle identification program backtags from livestock to evade the provisions of the law. This rule applies to both intrastate and interstate movement scenarios.
For a comparison of how a neighboring state handles movement rules, see brucellosis laws in Minnesota or check brucellosis laws in Michigan.
Reporting and Quarantine Requirements in Illinois
Illinois law treats brucellosis as a reportable disease, meaning that suspected or confirmed cases must be communicated to state authorities promptly. This reporting structure is central to maintaining the state’s Class Free status and enabling rapid response when a potential case is detected.
For a full list of reportable diseases for all animal species, producers can refer to the Illinois Department of Agriculture’s Reportable Diseases Page. Veterinarians and owners play a role in reporting suspect cases to the Illinois Department of Agriculture or the USDA Illinois District Office.
Under the Illinois Diseased Animals Act (510 ILCS 50) and the Illinois Bovine Brucellosis Eradication Act (510 ILCS 30), the Illinois Department of Agriculture has broad authority to act on suspected brucellosis cases. Key reporting and quarantine provisions include:
- Any accredited veterinarian who identifies a brucellosis reactor or suspects brucellosis in a herd must report the finding to the Illinois Department of Agriculture.
- The Department has authority to quarantine any premises where brucellosis-infected or brucellosis-exposed animals are located.
- Quarantined animals may not be moved off the premises without Department authorization.
- Disease control and eradication measures include quarantines to stop the movement of possibly infected or exposed animals, testing and examination to detect infection, destruction of infected (sometimes exposed) animals to prevent further disease spread, and cleaning and disinfection of contaminated premises.
A “suspicious animal” or “suspect” means an animal that has given a positive reaction to an official test and whose test results are less than that which would result in a classification of reactor. Suspects trigger an immediate investigation and may be subject to quarantine pending further testing.
The Illinois Administrative Code at Part 75 includes specific provisions for the release of feeding or grazing cattle from quarantine (Section 75.170) and for cattle or bison movement under quarantine conditions (Section 75.180). These sections establish the conditions under which quarantined animals may be moved to slaughter or otherwise managed while the investigation proceeds.
For context on how Illinois handles other animal-related reporting and regulatory obligations, you can review roadkill laws in Illinois or explore backyard chicken laws in Illinois.
Penalties for Brucellosis Violations in Illinois
Illinois takes brucellosis violations seriously, and the penalty structure under the Illinois Bovine Brucellosis Eradication Act (510 ILCS 30) and related statutes reflects the public health and economic stakes involved. Violations can result in civil penalties, criminal charges, and the loss of herd certifications.
Criminal Penalties
Under the Illinois Bovine Brucellosis Eradication Act, knowingly violating the provisions of the Act or the regulations issued under it is a criminal offense. Specific prohibited acts include:
- Importing dairy or breeding cattle without a valid official interstate health certificate showing a negative brucellosis test.
- Moving quarantined animals off a premises without Department authorization.
- Removing identification tags, numbers, brands, ear tags, microchips, or market cattle identification program backtags from livestock to evade the provisions of the law.
- Changing the names, numbers, words, phrases, or other information on an official health certificate, permit, or other official document to evade the provisions of the law.
Violations of the Illinois Bovine Brucellosis Eradication Act are classified as Class B misdemeanors under Illinois law, which can carry fines and potential jail time depending on the circumstances and whether the violation is a first or repeat offense.
Civil and Administrative Penalties
Beyond criminal liability, the Illinois Department of Agriculture can take a range of administrative enforcement actions against violators:
| Violation Type | Potential Consequence |
|---|---|
| Importing cattle without required health certificate | Quarantine of animals, mandatory testing at owner’s expense, civil fine |
| Moving quarantined animals without authorization | Criminal charges, mandatory return or slaughter of animals, loss of dealer license |
| Altering or falsifying official documents | Criminal charges, civil penalty, permanent loss of certification |
| Removing official identification tags | Civil penalty, investigation, potential criminal charges |
| Failure to report a suspected brucellosis case | Civil penalty, potential quarantine of entire operation |
| Selling animals from a quarantined herd | Criminal charges, mandatory indemnity forfeiture, herd decertification |
Records and premises shall be open for inspection during regular business hours by authorized Department inspectors. Department inspectors are authorized to make photocopies of any and all records as necessary. Refusing or obstructing an inspection can itself constitute a separate violation under the Act.
Indemnity and Herd Depopulation
When a herd is confirmed positive for brucellosis, the Department may order depopulation of infected animals. In legitimate cases where the producer was not negligent or fraudulent, state and federal indemnity programs may compensate owners for destroyed animals. However, if a violation contributed to the introduction or spread of brucellosis — such as importing animals without required testing — indemnity payments can be reduced or denied entirely.
If you want to understand how Illinois handles other livestock-related legal matters, you may also want to read about dog bite laws in Illinois, dog chaining laws in Illinois, or kennel zoning laws in Illinois for a broader picture of Illinois animal law.
For comparison with how other states structure their brucellosis penalty frameworks, see brucellosis laws in Nevada.
Conclusion
Illinois has earned and maintained its brucellosis-free status through decades of cooperative effort between producers, veterinarians, and state and federal agencies. The legal framework — anchored by the Illinois Bovine Brucellosis Eradication Act (510 ILCS 30) and 8 Ill. Adm. Code Part 75 — reflects that ongoing commitment through clear rules on vaccination, testing, movement, reporting, and enforcement.
As a cattle or bison owner in Illinois, your compliance responsibilities center on three core areas: ensuring that any animals entering your operation from other states carry proper documentation and testing records, maintaining accurate identification on all animals, and reporting any suspected brucellosis cases to the Illinois Department of Agriculture without delay. Staying current with these obligations is what keeps Illinois’s Class Free status intact — and protects the value and marketability of your herd.
For any questions about specific requirements, contact the Illinois Department of Agriculture’s Animal Health division directly, or consult with an accredited veterinarian familiar with Illinois brucellosis regulations. You can also review the USDA APHIS National Brucellosis Eradication Program for federal-level guidance that underpins Illinois’s state program.