The July 7, 2010, a press release from the Ohio Department of Agriculture (ODA) announcing that a dairy herd had recently been detected with bovine tuberculosis (bTB) and subsequently depopulated was perhaps a surprise to some people, but to those who have been observing similar kinds of discoveries in other states, it was not. In fact, in an article in the Ohio BEEF Cattle Letter that appeared just before the ODA press release, we briefly discussed biosecurity and the concern of introducing diseases, like TB and others characterized by “silent” infections, into herds and flocks. In the short term, the impact of this discovery on Ohio farmers will be rather minimal and limited to the herd affected, the herds in which animals from this herd were traced, and the regulatory agencies charged with the tracing and testing activity (of course, they are supported with our tax dollars). Should additional herds be discovered in the next two years, the possibility of loss of our “free” status with respect to bTB exists. This could have a profound impact on Ohio farmers.
The current situation in Ohio and the U.S., with respect to bTB, does give us some insight into changes that have occurred over the past 20 to 30 years. Herd size has tended to increase, especially in the dairy industry. Some of this expansion occurred with retention of natural additions to herds, but for many herds, it also involved movement of animals from one herd to another. In some cases, bTB has been traced to Mexican cattle entering the US as Holstein feeder animals and roping/rodeo steers. Unfortunately, in a few cases, contact between these animals and other animals destined for breeding herds has occurred. This time frame has also seen the growth of farmed deer, elk, and bison herds, much of which was unregulated until recent years and in which some level of bTB may have persisted.
The conspicuous feature of this change is the nature and amount of animal movement. In a recent news article, it was reported that last year more than 19 million of the nation's 30 million beef cows and 9 million dairy cows crossed state lines (1). It is now fairly common for herds, both beef and dairy, to contain animals that were born in one state; raised, comingled with other animals, and bred in one or more different states; and relocated to yet another for breeding or production purposes. In fact, in the Ohio herd recently found with bTB, the animals in that herd had their origin in at least 17 different states and Canada. Much of this movement is done with no, or minimal, attention to the potential for introduction of disease. Some of it is done illegally; perhaps more than we would like to believe. The recent National Animal Health Monitoring System (NAHMS) surveys suggest that routine biosecurity measures for animal disease prevention are not regularly practiced by many farms (2). Diseases like bTB, Johne’s disease, anaplasmosis, and bovine viral diarrhea (BVD) are readily moved about by animals that are infected but which show no visible signs of disease. This tremendous amount of movement of animals back and forth across the country, which happens virtually every day, has led some people in the animal health field to observe that we now have a “national” herd merely split up among different temporary owners. To the extent that animals are moved without individual identification and records, the job of tracing disease outbreaks becomes enormous.
Perhaps this is a good time to discuss “health certificates.” Actually, the term “health certificates” is a bit of a misnomer since they do not really certify the complete “health” of the animals being moved. Although the term is still used almost universally, today it is reserved for forms and certificates provided by the USDA for interstate and international animal movement (including dogs and cats). Most states, including Ohio, now issue a “certificate of veterinary inspection” which perhaps more appropriately describes what they are. They are the paperwork that is usually required for interstate, and sometimes intrastate, movement of animals. They list all official forms of identification of each of the animals, their source/owner and destination, and the results of any tests that may have been required for movement to the destination. In some cases, no actual animal tests are required. They also require the signature of a veterinarian that indicates that he/she has performed the appropriate tests, that the information on the certificate is correct and complete, and that he/she has examined the animals for evidence of infectious or contagious disease. Some states require additional statements regarding the status of a specific disease for the source herd to be placed on the certificate. An accredited veterinarian and state of origin issue the certificate with the original accompanying the animal and copies sent to the state of destination.
Although the certificate of veterinary inspection is a very important legal document and does verify testing and examination for some kinds of diseases, it does not imply that the animals listed on the certificate are free of disease. For infectious diseases that have long incubation periods, like bTB, or diseases that may be transmitted from apparently healthy carriers or shedders, like Johne’s disease, BVD, or anaplasmosis, a “health certificate” may provide little protection to the farm or herd of destination. Furthermore, the requirements for interstate and intrastate movement may vary somewhat by state, depending on what a state believes is in the best interest of their citizens. For example, a disease of beef cattle that is getting more attention every year is trichomoniasis (commonly called “trich”), an infection carried by non-virgin bulls that can be transmitted to cows at breeding and cause early embryo loss and a high level of open cows at calving. It has been most common in several western states and is gradually spreading to other states. Some states require multiple tests for this infection on bulls prior to them entering their state, and some do not. Currently, a farmer in Ohio can buy a potentially infected bull from another state and move it to Ohio without any testing for this disease.
The United States embarked on a bTB eradication program in 1917 at a time when an estimated one in every nine human deaths was from TB. It has been estimated that 10% or more of those human TB cases were due to the bovine form acquired from cattle or indirectly from cattle products. (3) That estimate does not count the crippling, non-fatal infections. We made astounding progress in just the first few decades, thanks to the financial and moral commitments of your grandparents and mine, and we continued to make significant strides toward eradication through the early 1990s when most states were declared “Free” and granted that status by the federal government [For a very interesting account of this read (3)]. Today, many states do not require TB testing for cattle being imported from “Free” states.
So We Have bTB. “What’s All the Fuss About?”
Since the bTB eradication program began in 1917, huge changes in the livestock industry have taken place. By the late 1980s, most states had been given “Accredited Free” status with respect to bTB. Although the disease was not eradicated, the prevalence had become so low that infected herds were only infrequently detected. These herds were almost always depopulated quickly, and often no evidence for further spread was found.
In the early 1970s, the “every-six-years” bTB testing of cattle herds by township was discontinued in Ohio. Sometime in the early 1980s, routine testing of Ohio-origin cattle being exhibited in Ohio was discontinued (Yes, I am old enough to remember doing township TB testing and TB testing 4-H market steers going to the county fair). For many years, the primary form of surveillance for bTB has been routine post mortem inspection at state and federally inspected slaughter facilities, although some routine herd and individual animal testing is still done. The USDA does not currently require bTB testing for most classes of cattle if they move between Accredited Free states, and many states, but not all, have similar rules for importation of cattle into their state (4). Ironically, the success of the bTB eradication effort, along with the largely successful effort to eradicate bovine brucellosis, may have created a sense of complacency.
Having USDA “Accredited Free” status has been a major benefit for a state’s livestock producers. However, for sneaky diseases with long incubation periods and imperfect diagnostic tests, like bTB, the potential for spread is always present until they are completely eradicated. With the coming of today’s large, multi-source herds; the tremendous amount of movement of animals for breeding, feeding, grazing, and exhibition; and the reduced level of animal and herd testing, outbreaks of bTB in many states over the last decade are not too surprising. And the meaning of “free” may not mean the same thing now that it did in 1985. Until very recently, the finding of two or more infected herds within a state within a 48-month period caused it to lose its free status. The states of CA, NM, MI, and MN have all lost their free status over the past decade, and several more have discovered infected herds in very recent years (TX, NE, IN, KY, CO, SD, and now OH). For MI and MN, the discovery of wild white-tailed deer with bTB in the areas where cattle herds with bTB were found has tremendously complicated their efforts to regain free status. In the past, when a state lost its “Accredited Free” status, farmers and ranchers of that state who wished to sell or move their animals interstate or internationally had to test their animals or herds to be eligible for movement. The resulting costs to the individual and the state can be enormous as exemplified by the situation in Michigan since the discovery of bTB in the northeastern Lower Peninsula in 1994.
Last year, the USDA published its intent to develop a new approach to its management of bTB (5). This was driven by the recognition that the current rules were developed before changes in herd size and animal movements have come about and that the actual number of infected cattle in infected herds tends to be small. Requiring depopulation of all animals in infected herds, and paying indemnity for them, has become very expensive and harder to justify to a public that is more animal welfare conscious. The steps needed for a state to regain its free status require a tremendous investment in public and private resources, and the unaffected farms in that state share heavily in that burden. In a Federal Order issued on April 15, 2010, the USDA announced its intention to suspend its enforcement of federal law that downgrades a state’s “Accredited Free” status to a lower status when bTB is found provided that the state animal health officials:
- “Are maintaining all affected herds under quarantine;
- Have implemented a herd plan for each affected herd to prevent the spread of tuberculosis;
- Have implemented a program to periodically test the animals under quarantine for tuberculosis and remove and destroy those that do not test negative; and
- Are conducting surveillance adequate to detect tuberculosis if it is present in other herds or species.” (6)
In addition, cattle from herds in that state that are not known to be infected with, or exposed to, TB may be moved interstate without restriction for TB. Indemnity for herd depopulation will still be available “when the evaluation indicates that other options will not mitigate disease spread, there is an imminent public or animal health risk, and/or it is cost-beneficial to do so.” Similar policy is being extended to states that have had their status downgraded one level providing there is no evidence of a wildlife reservoir. The USDA intends to reevaluate this Order in two years.
This is good news for most producers in states that have had their status downgraded and for states that have already found a bTB infected herd within the last few months. It will ease the USDA-imposed bTB restrictions for interstate movement for them and reduce the cost of doing business. It also somewhat reduces the burden on state animal health officials.
However, for farmers whose herds are found to have bTB, little is changed. Indemnity may still be an option, but federal monies for indemnity have been very sparse in the past few years. Approximately $207 million of emergency funding has had to be infused into the bTB program since 2001 (5). Much of this went for indemnity payments and tracing efforts to and from infected herds. If the funds available for indemnity don’t change, it is possible, if not likely, that farmers will be expected to share more of the burden of having bTB. An infected herd may not have to depopulate, but they will remain in quarantine, and the herd plan will almost certainly require multiple years of intensive testing if they expect to regain uninfected status. Commercial dairy farms may be able to remain in business, but the animals that leave the farm will have to go directly to slaughter under supervision of the state authorities or into approved feeding facilities. Slaughter markets may be somewhat limited as not all plants may want to deal with the requirements for slaughter of cows from these herds. For commercial beef herds, requirements for animals leaving the farm may make marketing them very difficult. For purebred herds selling seed stock, being under quarantine could effectively end those sales.
The bigger picture requires answering the question of how we will decide to deal with bTB for the future. If we expect to really eradicate the disease, it will take a renewed commitment on the part of the livestock industry and government. Because government money comes from taxpayers, it may mean they will have to be convinced that there is benefit to everyone to justify the cost. Furthermore, since much of the risk to public health is controlled by pasteurization of milk and inspection of meat, there may be reluctance to support what might be viewed now, almost 100 years after eradication efforts began, as “only” a livestock problem that should not be supported with public monies. There is current precedent for this very opinion in the United Kingdom (UK) (7). The bTB in the UK has become an enormous problem where there are now several thousand farmers living with bTB restrictions on their herds. The bTB problem in the UK is complicated by a significant reservoir of the disease in wildlife, principally the European badger, and reluctance by government and the general public to cull them even in high-risk areas. We must not let the disease become established in wildlife populations – for many reasons. England’s Bovine TB Advisory Group report, published about a year ago, provides us with a glimpse of the challenges we face if our bTB situation deteriorates. A quote from that Report is instructive:
"Finally, there is a need to acknowledge the human costs of this disease. TB has negative effects not only on the health of animals and trade but also the health and well-being of the herd owners involved. It has become apparent in discussions with industry that the stress of dealing with herd breakdowns, particularly in areas of repeated or extended breakdowns, has very real effects on individuals that extend beyond the immediate cost of the animals that are slaughtered. Some form of support (both business advice and direct financial support) is needed to help farmers to manage the impact of living under disease restrictions.” (8)
If we expect to effectively manage, let alone eradicate, bTB, we must realize that our individual actions regarding the biosecurity of our herds and flocks impact everyone, including people not involved in livestock production (9). And, we must develop a more effective system of livestock traceability to enable livestock disease control officials to track the movements of diseased and exposed animals. Those herd owners that have had to deal with a bTB infection in their herds can attest to the value of having even minimal methods of identification and recordkeeping in reducing the impact on their farm.
Animal Identification (ID), Traceability, and the Future of bTB Control
When I first began veterinary practice in 1971, cows on many farms were identified by names such as “Blackie,” “Bonnie,” or “Sparky.” (Ah yes, I remember Sparky well!) Since then, there has been an explosion in the methods one can use to identify animals. These range from simple numbered metal and plastic ear tags to sophisticated electronic identification systems that allow storing much more information about an animal than just a number on an ear tag. Tags and boluses that not only identify the animal but which can also monitor body temperature and report it to a hand held device or computer are now available as well (10). Systems are being tested that could allow remote monitoring of an animal’s location via computers and GPS technology. In fact, one of my colleagues has been using this technology for some time to track wild ducks in his avian influenza research program.
Not all of these new systems will prove commercially viable for the livestock industries, but some have already proven their usefulness. As long as three years ago, I collected blood samples from animals in a 300-cow beef herd that were identified with radio frequency identification (RFID) tags, and we were able to scan their ID directly into a computer and print off bar-code labels for the blood vials right beside a working chute located far from a barn. The capability exists to use this technology to scan animal ID directly into animal health forms and for a laboratory to scan the bar code on the blood vial to put that information into their computer system and subsequent reports. This has tremendous potential to reduce human error in the testing process and to make work faster and easier at the farm and laboratory. The RFID tags used at this farm have had an extremely high retention rate and have frequently allowed the correct ID of animals that have lost their visual ID tag, making them a valuable tool in animal management.
It was recently reported that “Last year, more than 19 million of the nation's 30 million beef cows and 9 million dairy cows crossed state lines” (11). Available data suggest that only about 28% of adult cattle have any form of official ID that would readily allow tracing their movement in case of a disease outbreak (11). “Official” ID refers to a method of ID unique to an animal or premise that is specified by state or federal government. Approved methods vary somewhat by state, species, and class of livestock but are typically ear tags, registry numbers, and tattoos. Perhaps, the most familiar of these are the alphanumeric metal ear tags from the National Uniform Ear Tagging System and which are provided by the USDA. These typically begin with a two-digit number that is unique to a state, followed by capital letters and then four numbers, such as 31ATM4444. The “31” indicates that the tag was applied by a veterinarian to an animal that was located in Ohio. Official tags are now available that use the 15-digit international standard numbering system, including RFID tags. The national Scrapie Eradication Program uses a special premise ID numbering system, and all breeding sheep, most exhibition sheep, and any sheep over 18 months old must be identified when they change ownership or move in interstate commerce. This identification scheme has been in place since late 2001, and we are making remarkably good progress in eradicating scrapie.
Officially identified animals, accompanied by appropriate paperwork, allow animal disease officials to trace animals that may be exposed or otherwise involved in a disease outbreak after they have left the farm. However, the system is far from perfect and can fail us. Unfortunately, this may be when we need it most, such as in outbreaks of serious disease like bTB, brucellosis, or, heaven forbid, foot and mouth disease. There are some common ID problems animal health officials encounter in tracing animals involved in disease outbreaks. The first is that ear tags are notorious for becoming lost. If an animal that has lost its tag is not retagged, and is subsequently comingled with other animals without ID, its identity may be gone and finding it again may be very difficult. This problem is compounded by failure to keep records on animals and their comings and goings at the herd level. As an example of this, imagine a situation where an animal is exposed to bTB in one herd and is then sold for breeding or into another commercial channel where it finds its way to a second herd. Assume that a short time after it entered the second herd, it lost its tag and the tag was not replaced, or the replacement tag number was not recorded in such a way as to link it with the first one. If bTB is diagnosed in the original herd, tracing of animal movements from it may lead to the second herd, but finding that exposed animal may now be impossible, especially if the second herd is a relatively large one. This may require quarantining the entire second herd and testing all the animals until it can be fairly certain that bTB has not become established in it.
Another problem is the removal of ID tags after an animal is relocated. This might be done to facilitate the record keeping system at the second location or because the old tag was difficult to read. If the old tag number, and the available RECORDS on that animal, is not retained, future ID of it may be impossible. It is important to know that intentional removal of an official form of ID is against the law. Of course, the reason for this is to maintain a way to trace an animal’s movement or source in the event of disease exposure. Official ID tags from USDA, like those of the National Uniform Ear Tagging System, can be recognized by a shield with the characters “US” inside it printed or stamped on the tag.
A third animal ID problem regulatory veterinarians frequently encounter during disease investigations is that an animal is found with multiple tags; perhaps all of them Official ID tags. This indicates that the animal probably has been moved across state lines multiple times, but it may be impossible to track that movement, except for perhaps the most recent instance, and multiple tags could even delay the tracing effort. Multiple tags in an animal may happen for several reasons, but it is usually because the last time an animal was moved, it was difficult or inconvenient to read an existing tag, and it was simply easier to apply a new one. If multiple forms of official ID are present on an animal, all of them should be recorded on a Certificate of Veterinary Inspection and a new one should not be added. All official ID should be a part of an animal’s permanent record on the farm. Keeping those records is as much a protection for the owner as it is a tool for regulatory officials in tracking disease and exposures. Farm records need not be complicated or elaborate, but having them and being able to provide ID and information about an animal’s movement history in the event of a trace-out of disease to the farm may make the difference between experiencing an inconvenience and being quarantined and having to test the herd.
During USDA fiscal year 2009, six bTB cases in fed cattle (non-adult) were detected at slaughter (12). Fortunately, ear tags allowed ID of the source herds and travel history for three of those animals. However, no unique animal ID was available for one feedlot-origin animal, and multiple consignors had contributed to the feedlot pen from which it had originated. If animal ID is not available, or not recorded, at the slaughter plant where most surveillance for bTB is done, tracing investigations on all animals in a pen or shipment may be necessary to try to locate the source of the infection.
Even when the source herd for a TB-infected animal can be identified easily, the subsequent investigations can be an enormous effort. As just one example illustrates - in April of 2009, a cull cow with bTB was detected at slaughter, and the source herd of 800 adult beef cows in north central Nebraska was identified. Subsequent testing of this herd detected an additional infected cow (12). Investigation of the cow movements into and from this herd, as well as fence-line contacts, resulted in the quarantine of 61 herds in 20 counties and the testing of 21,764 animals (13). No additional infected herds were found, but the costs of testing, borne by taxpayers and herd owners, and the financial and emotional strain of quarantine on herd owners are not easily quantified.
Earlier this year, the USDA announced that it was abandoning its plan to develop a National Animal Identification System (NAIS) that has been in the development phase for several years and which was somewhat controversial. In February, it announced that it was initiating a new effort to develop a framework for animal disease traceability (14). It is holding a series of public meetings and has solicited the assistance of the stakeholders in the livestock industries in developing the plan. It would apply only to animals moving in interstate commerce and would be implemented by the states. Coordinating individual state plans for making traceability both usable and efficient will be a major challenge. Obviously, an effective system will be of benefit for tracking important diseases other than bTB.
In her report to the Committee on TB at the October 2009 meeting of the United States Animal Health Association, Dr. Alecia Larew Naugle, National TB Program Manager (and 1998 OSU Veterinary College graduate), suggested that farmers consider the following with respect to bTB and the need for a new approach to managing it:
“In this new approach, producers and industry will also have responsibilities:
- Advancing their knowledge about bovine TB and risk factors for introducing TB into their herds,
- Evaluating their management practices to identify if any of these risk factors are present and implementing mitigations to reduce these risks,
- Developing industry- and producer-driven components of the TB program and generating the funds necessary to support these activities , and
- Continuing to engage in discussions with State and Federal animal health officials concerning the TB program.” (12)
If we, collectively, decide that the bTB eradication program, started by our grandparents in 1917, is important to finish, we can do it. We have the technology and basic infrastructure to do so if we want to. Writing in the American Journal of Public Health in 1973, Roswurm and Ranney wrote: “The primary problem we face in tuberculosis eradication is a people problem.” and in the following paragraph: “The result is that in the animal health field, we have a few people that have considerable interest in seeing the bovine tuberculosis program completed; and many, many people who care little about this work. The people problem transcends all of the technical problems.” (15) We, the people, have to decide what inheritance we will leave our grandchildren.
- http://nahms.aphis.usda.gov/beefcowcalf/beef0708/Beef0708_is_Biosecurity.pdf and http://nahms.aphis.usda.gov/dairy/dairy07/Dairy07_ir_Biosecurity.pdf
- Olmsted, A. and Rhode, "An Impossible Undertaking: The Eradication of Bovine Tuberculosis in the United States." 2004. The Journal of Economic History vol. 64, No. 3 at: http://www.unc.edu/~prhode/Impossible_Undertaking.pdf
- http://www.aphis.usda.gov/animal_health/animal_diseases/tuberculosis/downloads/tb-umr.pdf USDA Uniform Methods and Rules for bTB
http://www.aphis.usda.gov/animal_health/animal_diseases/tuberculosis/downloads/tb_concept_paper.pdf “A New Approach for Managing Bovine Tuberculosis: Veterinary Services’ Proposed Action Plan”
USDA Concept Paper, Issued July 2009 and available early fall 2009
- http://www.aphis.usda.gov/newsroom/content/2010/04/printable/federal_order_tb.pdf Federal Order -- Bovine Tuberculosis: Requirements Applicable to Accredited-Free and Modified Accredited Advanced States or Zones . April 15, 2010.
- Torgerson PR and Torgerson DJ. Public health and bovine tuberculosis: what’s all the fuss about? Trends in Microbiology 2010 Volume 18, No. 2 pp. 67-72.
- http://www.defra.gov.uk/foodfarm/farmanimal/diseases/atoz/tb/documents/tbag-finalreport.pdf “Bovine Tuberculosis in England: Towards Eradication” A Final Report of the Bovine TB Advisory Group. April 8, 2009.
- http://beef.osu.edu/beef/beefJune1610.html the Ohio BEEF Cattle Letter, Issue # 691, June 16, 2010, Miller and Shulaw articles.
- http://www.drovers.com/directories.asp?pgID=712 - a list of identification device suppliers.
- http://www.usatoday.com/news/washington/2010-08-08-livestock-usda-regulations_N.htm USA Today (online issue), August 8, 2010.
- http://www.usaha.org/committees/reports/2009/report-tb-2009.pdf - Proceedings of the 113th United States Animal Health Association Meeting, report of the Committee on Tuberculosis, October 2009.
- http://www.midwestagnet.com/Global/story.asp?S=12276490 Midwest AGnet, April 8, 2010.
- http://www.aphis.usda.gov/traceability/ - announced February 5, 2010.
- Roswurm JD, Ranney AF. Sharpening the attack on bovine tuberculosis. Am J Public Health 1973;63:884-886.