U.S. Senate Committee on Environment & Public Works
U.S. Senate Committee on Environment & Public Works
Hearing Statements
Date:   04/06/2004
 
Statement of Dr. Jack O. Walther
President
American Veterinary Medical Association
Washington, DC
Chronic Wasting Disease Financial Assistance Act of 2003.

Thank you Mr. Chairman and members of the Subcommittee for giving the American Veterinary Medical Association the opportunity to come before you today to speak in support of Senate Bill 1366.

I am Dr. Jack Walther, President of the AVMA. I was born and raised on a small ranch near Reno and now practice in Elko, Nevada.

The AVMA represents 86% of active veterinarians in the United States. Our membership consists of 70,000 members, most of whom have treated wildlife during their careers. In addition, hundreds of veterinarians have a primary professional focus in wildlife medicine. For the past 141 years, the AVMA has worked to advance the science and art of veterinary medicine. Veterinarians have a long history of positively impacting the health and well being of humans, animals and the environment. A few noteworthy members of my profession are Dr. Daniel Salmon, who first described salmonella in 1855, and Dr. Tracey McNamara, who first identified West Nile virus in the United States. Additionally, many of our members are public servants, such as Dr. Lester Crawford, Acting Commissioner of the Food and Drug Administration, and Dr. Ron DeHaven, Deputy Administrator of Veterinary Services at USDA. Veterinary public servants also include the Senator from my home State of Nevada, Senator Ensign, and the Senator from Colorado, Senator Allard. Today, many veterinarians are dedicating their professional skills to studying chronic wasting disease and other diseases that effect both animals and humans.

CWD is one of many transmissible spongiform encephalopathies (TSEs). These are important diseases worldwide that are of particular concern to the veterinary community. The AVMA was proactive many years ago in addressing this important disease and issue. We developed a scientifically based position statement (attached) that supports the purposes of Senate Bill 1366.

Our position statement commits the AVMA to:

· disseminating scientific knowledge;

· encouraging enhanced surveillance, monitoring, and control programs; and

· encouraging governmental support for the development of new rapid diagnostic tests and control measures.

We recognize and applaud the on-going efforts of the Department of Interior and the Department of Agriculture, and state and tribal agencies to implement the National Plan for Assisting States, Federal Agencies, and Tribes in Managing Chronic Wasting Disease in Wild and Captive Cervids. Much has been accomplished but more remains to be done. Additional funds must be allocated for state and tribal activities to ensure that the outcome of the comprehensive effort will be successful.

At the same time, we urge the Subcommittee to remember the need to address not only CWD, but also many other diseases impacting both wildlife and livestock. Some of these diseases also affect both humans and animals, such as brucellosis in bison and elk in the Greater Yellowstone area, brucellosis in feral swine, and tuberculosis in wild deer.

We live in a world of emerging disease threats. TSEs are one such threat. TSEs in animals include scrapie, bovine spongiform encephalopathy, and chronic wasting disease. They all pose serious risks to the health and welfare of animals. For states and communities that depend on income derived from outdoor activities, including hunting, these diseases pose serious economic risks.

Colorado Governor Bill Owens recently told a panel of experts and key stakeholders from the public and private sectors that CWD “affects every Coloradoan” and has the potential to severely damage hunting, tourism and related industries as well as the state’s unique natural resources.

Additionally, the most recent statistics from the Wisconsin Department of Natural Resources estimate that hunters in Wisconsin spend $897,000,000 annually on supplies, lodging and other expenses.

CWD can have a profound effect on agriculture, wildlife, and zoo management. Because CWD touches so many stakeholders, it is essential that programs addressing CWD be cooperative in nature. Nowhere is cooperation more vital than between agriculture and wildlife management agencies and groups at the state, national and international levels. Disease does not respect fence lines or state and international borders. CWD has affected deer and elk in Colorado, Illinois, Kansas, Minnesota, Montana, Nebraska, New Mexico, Oklahoma, South Dakota, Utah, Wisconsin, Wyoming, and in the Canadian provinces of Alberta and Saskatchewan.

We must work together to find solutions. Effective solutions will require a philosophical and economic commitment to disease surveillance, to disease management, to diagnostics, and to research.

The AVMA supports Section 4 of the bill that will provide grants to assist states in responding to CWD outbreaks in wild deer and elk. Additional funding to permit rapid and effective responses is absolutely essential. We also support Sections 3 and 5 of the bill that provide capacity-building grants to state and tribal wildlife management agencies. These grants will enable implementation of long-term management strategies, including surveillance. Testing is needed in more states and tribal lands to determine whether the disease exists in new locations. If CWD does exist in other areas, additional testing is needed to define its prevalence, incidence, and distribution.

The extent of testing and surveillance that is needed now, and for the foreseeable future, exceeds resources available to state departments of natural resources and tribal organizations. Financial support from the Federal government will be required to comprehensibly and effectively test wild elk and deer populations.

As an example, Governor Doyle of Wisconsin recently directed that $900,000 be spent to improve testing capacity for CWD in his state. This amount will support testing for research and disease management, but does not fund testing of hunter-harvested deer. Federal grants are needed to provide additional funds to enable the states to do more surveillance testing.

The “Chronic Wasting Disease Financial Assistance Act of 2003” positively and rightfully recognizes and rewards states and tribal governments that have integrated CWD wildlife and agriculture programs. The AVMA supports this prioritization.

One clause of Section 4 that deserves further study, however, is the language that assigns priority for funding to states on the basis of previous state expenditures on CWD management and research. We agree with the idea that states should be rewarded for being proactive in managing CWD. However, states with fewer available resources may be inadvertently precluded from receiving grants. They may have been unable to fund surveillance programs and, therefore, have not been able to detect CWD in their state. These states should be given grants to support surveillance programs to determine whether CWD exists within their borders. CWD could potentially affect the entire United States therefore, Congress must be sure that states and tribal governments with the greatest need receive a fair share of the available Federal monies.

Senate Bill 1366 goes a long way in preventing any further negative impact from CWD on animal health, the environment and our national economy. The leadership, staff and members of the American Veterinary Medical Association stand ready to assist in any way that we can in this matter.

In keeping with our official policy, the AVMA has a strong presence and significant positive impact on professional and public education with respect to TSEs. We keep our members informed through two scientific journals, background materials (copy attached) on our Web site, and continuing education sessions presented during the Association’s annual convention. In turn, veterinarians provide accurate and useful information to clients and the public. To further assist veterinarians in educating the public, the AVMA produced brochures dealing with CWD and BSE. More than 15,000 copies have been distributed. We regularly respond to public and media needs for information by issuing print, electronic, and audio news releases, and by participating in interviews with writers and broadcasters.

TSEs present a serious and possibly growing threat to many of our nation’s animal populations, as well as to state and local economies. Senate Bill 1366 is an important step toward successful control of CWD and we are extremely pleased and proud to have been afforded an opportunity to appear before you to speak in support of its passage.

American Veterinary Medical Association Position Statement on Spongiform Encephalopathies

Transmissible Spongiform Encephalopathies (TSEs) are important diseases worldwide. The AVMA will disseminate scientific knowledge of the etiology, epidemiology, prevention, and control of TSEs. AVMA supports and encourages enhanced national and state surveillance, monitoring, and control programs. The AVMA encourages the USDA and DHHS to support research for the development of new rapid diagnostic tests, control measures, cleaning and disinfecting procedures, and the zoonotic potential. The AVMA further encourages FDA to provide educational materials and to monitor and enforce the mammalian protein ban in ruminant feed. (EB 5/03)

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CWD Backgrounder (3/26/04)

Causative agent

Chronic wasting disease (CWD) belongs to the family of diseases known as the transmissible spongiform encephalopathies (TSE). The causative agent of CWD has not been fully characterized, but three possibilities have been proposed: an unconventional virus, a prion (a self-replicating protein), or a virino (incomplete virus) comprising naked nucleic acid protected by host proteins. The CWD agent does not invoke a detectable immune response or inflammatory reaction in its host. On the basis of what is known about other TSEs such as bovine spongiform encephalopathy and scrapie, it is assumed the causative agent of CWD is extremely resistant to sterilization processes.

Natural distribution An infectious, neurologic disease, CWD develops naturally in North American deer and elk. Species found to be affected include Rocky Mountain elk, mule deer, white-tailed deer, and black-tailed deer. Chronic wasting disease was first diagnosed in a Colorado captive elk research facility in 1967, and was identified as a TSE in 1978. It was found in the mid 1980s in free-ranging deer and elk in adjoining areas of Colorado and Wyoming. In May of 2001, CWD was identified in deer residing in the adjacent portion of Nebraska. Free-ranging cervids in Illinois, South Dakota, New Mexico, Utah, Wisconsin, and the Canadian province of Saskatchewan have also been affected. The first infected farmed herd was discovered in South Dakota in 1996. Chronic wasting disease has also been diagnosed in captive cervids in Colorado, Kansas, Minnesota, Montana, Nebraska, Oklahoma, Wisconsin and the Canadian provinces of Alberta and Saskatchewan.

Transmission

Although many years of research have been conducted, the exact mechanism of transmission of CWD is still unknown. Currently transmission is believed to be lateral (animal to animal) and to take place through contact with or exchange of bodily fluids such as saliva, urine, feces, or placental tissue. Evidence also exists suggesting that vertical (mother to offspring) and environmental transmission is possible. Feed contamination is not considered to be a likely means of transmission; however, supplemental feeding may concentrate populations of cervids and facilitate animal-to-animal spread.

Clinical signs of CWD in cervids

Most cases of CWD develop in adult animals. Chronic wasting disease causes progressive degeneration of the central nervous system. The most obvious and consistent clinical sign is progressive weight loss and dehydration. Other clinical signs include changes in temperament (e.g., loss of fear of humans, nervousness, or hyperexcitability), changes in behavior (teeth grinding, walking in repetitive patterns in pens), incoordination, polydipsia, polyuria, drooping of the head and ears, and excessive salivation. Incubation period is typically 18 to 24 months, but can range up to 36 months. The health of affected animals typically deteriorates over a period of 12 months after infection. Chronic wasting disease is uniformly fatal.

Diagnosis

At the present time, CWD is diagnosed by postmortem microscopic examination of brain stem (particularly the obex portion) and lymphoid (lymph nodes and tonsils) tissues. Lesions of CWD resemble those of other spongiform encephalopathies. Immunohistochemistry (IHC) is very sensitive and specific to CWD and is used to confirm diagnosis by measuring accumulations of proteinase-resistant prion protein (PRPres) in brain tissues of infected deer and elk. Accumulations of proteinase-resistant prior protein have not been found in uninfected cervids. Positive test results are not detected until at least 3 months after infection so negative results cannot confirm the absence of disease (it is possible that the animal is infected, but the stage of the disease is so early that the prion is not detectable). Colorado researchers have developed an antemortem (live animal) tonsillar biopsy test for CWD, which appears to work well for mule deer, but not for elk.

Prevention

Because transmission mechanisms are still not well understood, it is difficult to recommend measures to prevent spread of the disease. Surveillance, culling, and testing are performed in areas where cases of CWD have been identified in an attempt to contain the disease within that endemic area. Unfortunately, no vaccine or preventatives exist and there is no evidence that immunity to CWD develops.

Treatment

No treatment currently exists for cervids with CWD. The disease is uniformly fatal.

Infection control

The United States Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) provides assistance to state officials in diagnosing CWD and in monitoring international and interstate movements of captive animals to help prevent its spread. Several state and national appropriations bills have been passed to provide funding for much needed research on CWD. In an effort to contain and eventually eradicate CWD, state and federal agricultural and wildlife agencies are taking action including regulating and/or banning interstate movement of captive cervids, enforcing more stringent hunting policies, creating joint task forces, and developing state-specific guidelines.

Members of the general public, hunters, and owners of cervid game farms must be informed of the dangers CWD poses to deer and elk populations, and take precautions necessary to reduce transmission. Animals appearing to be ill should be reported to wildlife officials. Deer feeding and baiting should be limited as this is an activity that brings deer into close contact with one another. Double fencing of captive herds will lessen contact with wild animals, and vigilant surveillance and testing of these herds is recommended. Hunters should avoid harvesting deer or elk that appear sick; should wear rubber gloves while field dressing animals; should remove all bone and fatty tissue from the meat of the animals; should minimize handling of the brain, spinal cord, spleen, tonsils, lymph nodes, or eyes; should avoid consuming any animal with positive test results for CWD; and should not remove anything but pure meat (muscle) from endemic sites.

Transmissible Spongiform Encephalopathies in Other Animals

The family of transmissible spongiform encephalopathies (TSE) in animals includes scrapie, affecting sheep and goats; transmissible mink encephalopathy; bovine spongiform encephalopathy (BSE), commonly referred to as “mad cow disease,” affecting cattle; and, in humans, kuru, classic and variant Creutzfeldt-Jakob disease (CJD), Gerstmann-Straussler syndrome, and fatal familial insomnia.

At the present time there is no evidence that CWD is easily transmittable to livestock or other ruminants such as sheep, cattle, or goats under natural conditions. Livestock housed with infected deer or elk, or those having ingested brain tissue of infected animals, have not developed the disease. Chronic wasting disease has been experimentally transmitted to mice, ferrets, mink, goats, squirrel monkeys, and calves.

Implications of CWD for Humans

There is currently no evidence that CWD is naturally transmitted to humans, either through contact with affected animals or by eating meat from infected animals. The Centers for Disease Control and Prevention, however, has issued the following statement: “It is generally prudent to avoid consuming food derived from any animal with evidence of a TSE. To date, there is no evidence that CWD has been transmitted or can be transmitted to humans under natural conditions. However, there is not yet strong evidence that such transmissions could not occur. To further assess the possibility that the CWD agent might occasionally cause disease in humans, additional epidemiologic and laboratory studies could be helpful. Such studies include molecular characterization and strain typing of the agents causing CWD in deer and elk and CJD in potentially exposed patients. Ongoing national surveillance for CJD and other neurologic cases will remain important for continuing to assess the risk, if any, of CWD transmission to humans.” Routine precautions should be taken when handling carcasses of animals that may be infected.