HHS Secretary Tommy G. Thompson announced today that the Food and Drug Administration (FDA) will commission two studies to assess the human health risk of chronic wasting disease (CWD), part of a comprehensive effort to combat the spread of the disease in deer and elk herds across the country.
Overall, HHS has proposed spending more than $29.2 million in fiscal year 2003 to expand research efforts to fight the growing threat of prion diseases, including CWD among the nation’s deer and elk populations.
“We must determine whether CWD is a threat to our food supply and how best to stop the spread of this disease in our deer and elk herds,” Secretary Thompson said. “We will aggressively pursue innovative methods to expand research and direct assistance to states to fight the spread of CWD.”
The FDA-commissioned studies will be a formal risk assessment regarding the present potential human health consequences of CWD and the transmissibility of CWD. The purpose of these studies will be not only to try to determine and, if present, quantify the human health risk, but also to identify areas were data gaps exist and where research efforts should be focused to reduce the potential threat to health posed by CWD.
The FDA studies are being commissioned as the National Institutes of Health (NIH) has intensified its efforts to understand and fight this disease. Recently, a component of NIH, the National Institute of Allergy and Infectious Diseases(NIAID), awarded a 7-year, $8.4 million contract to Colorado State University to establish an emerging disease research center focused on CWD. Additionally, scientists at NIAID’s Rocky Mountain Laboratories (RML) in Hamilton, Montana, have initiated studies aimed at developing new therapies against CWD; and soon they will start critical experiments to answer a key question — can this disease be transmitted from deer or elk to monkeys, another model for assessing the potential for human transmission.
CWD is one form of a group of fatal brain diseases called transmissible spongiform encephalopathies, or TSEs. These diseases include bovine spongiform encephalopathy (BSE or “mad cow” disease) in cattle, scrapie in sheep and Creutzfeldt-Jakob disease in humans. The hallmark of TSE disease is accumulation in the brain of abnormal prion proteins — misshapen versions of the normal prion proteins found on the surface of brain cells. There is no evidence that CWD has caused illness in humans.
NIH has budgeted an estimated $24.3 million for TSE research in fiscal year 2002 and has requested $26.4 million in fiscal year 2003 — an 8.7 percent increase. Secretary Thompson called on Congress to move quickly to approve HHS budget for fiscal year 2003, which began Oct. 1.
“At a time when this devastating disease is harming deer and elk herds throughout America, we must do all we can to provide additional resources to research and combat CWD,” Secretary Thompson said. “This is groundbreaking research that will have tangible implications for hunters and farmers.”
Scientists do not know yet whether deer or elk with CWD might also transmit some form of TSE disease to people who eat or have close contact with them. With CWD beginning to spread over a wider geographical area in the United States, however, answering this question is of critical public health importance.
The new Colorado research center in Ft. Collins, headed by Edward Hoover, Ph.D., D.V.M., will investigate the mechanics of CWD infection in deer and elk, especially in the immune system’s lymphoid tissues. Such studies underlie the search for improved diagnostics and therapies. The researchers also will seek to better understand the entire spectrum of disease transmission and under what circumstances CWD might “jump” to other species. In addition, scientists at the center will work on a possible vaccine to prevent the spread of CWD in deer and elk. Glen Telling, Ph.D., of the University of Kentucky, will be a close collaborator with Dr. Hoover in this effort. Dr. Telling’s work is supported in part by the National Institute of Neurological Disorders and Stroke, another NIH component.
Researchers at NIAID’s RML have been studying TSE diseases, particularly scrapie, for decades, and have directed attention to CWD during the last few years. RML scientists plan to investigate whether the abnormal CWD prion protein, presumed to be the agent that causes the disease, can be transmitted from deer or elk to monkeys if the monkeys eat meat containing the abnormal prion proteins. That knowledge would provide valuable insight into whether or not CWD could be transmitted to humans. Recently, RML scientists established that another TSE disease, hamster scrapie, could jump species — adapting to and causing disease in mice.
RML scientists also are collaborating with researchers at Utah State University to test several new compounds, developed by NIAID scientists, that show promise in blocking the formation of abnormal prion proteins and therefore may one day be used as therapies to treat CWD or other TSE diseases. Some of these compounds may be able to decontaminate meat or other products infected with abnormal prion proteins.
RML scientists have also designed transgenic mice that promise to make studying CWD faster and less expensive. These mice carry the prion proteins of deer and elk, so their bodies react to the disease as a deer or elk would. That means scientists can study the disease in these mice rather than in the larger animals, which are much more expensive and labor-intensive to keep.
Finally, RML scientists have identified important differences between how CWD progresses in deer and how it progresses in elk. This discovery provides new insight into the nature of the disease.