Wildlife health is just one of many factors that can affect wild populations. Typically, diseases act subtly on wildlife and are seldom seen by hunters and outdoor enthusiasts. However, some diseases are quite visible, or may result in dramatic impacts to populations and the people interested in them. ODFW is currently monitoring the following five diseases to determine if they are present, and if present, their effect on Oregon’s big game. As a result, ODFW may be asking hunters for their assistance obtaining samples from their harvested game animals. Some hunters may be asked to bring samples from their game animals to department offices or check stations, while others may be contacted in the field for sample collection.
Chronic Wasting Disease (CWD) in Deer and Elk
CWD is a brain disease of wild and captive deer and elk that has occurred in Colorado and Wyoming for over 20 years. In the last four years, however, it has been found in free-ranging and/or captive mule deer, white-tailed deer and elk in Nebraska, Kansas, South Dakota, Montana, Oklahoma, Wisconsin, New Mexico, Minnesota, Illinois, Utah, Texas, Alberta, and Saskatchewan. CWD is untreatable and leads to progressive loss of body condition, behavioral changes, excessive salivation, neurologic deficits and eventual death. Researchers believe an abnormal type of infectious protein, called prions causes the disease. Prions have been found to occur normally in many animals but their function is not yet known. The origin and transmission method of CWD is not clearly defined. Once animals show symptoms, the disease progresses rapidly and animals die within 2–6 months. Similar diseases exist in domestic sheep (scrapie), cattle (bovine TSE or mad cow disease), and humans (Creutzfeldt-Jakob disease). Current research indicates CWD is not transmissible to humans. CWD has not been detected in any Oregon samples (sampling began in 1996). Despite these results, ODFW biologists remain extremely cautious and will continue to collect samples to insure the disease is not present in Oregon.
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What should Hunters Do?
Avoid shooting an animal that appears sick, is acting unusual, or is exhibiting any of the symptoms described above. If you observe such an animal, document the location of the animal and call your local ODFW office as quickly as possible. Additional information on these diseases can be obtained at your local department office or found on the Wildlife Health Program website. Hunters hunting in states known to have animals with CWD should read the parts ban information of the Big Game Regulations.
Adenovirus Hemorrhagic Disease (AHD) in Deer
AHD belongs to a small group of viruses that can infect a wide variety of animals, both wild and domestic. Infected deer can have clinical signs common to other diseases such as bluetongue or pneumonia. Chronic symptoms include sores in the mouth and throat. Acute symptoms include rapid or open mouth breathing, foaming or drooling at the mouth, diarrhea (possibly bloody), weakness, large amounts of fluid in the body cavity, and emaciation. Death can occur within 3 – 5 days from the time the deer was exposed to the virus. There is no treatment for individual deer infected with AHD. Transmission is by direct contact between deer, contact with bodily fluids, and possibly airborne routes.
In 2001, AHD was confirmed in one adult black-tailed deer doe and suspected in several dozen other deer deaths in southwest Oregon. In 2002, AHD was confirmed in an outbreak in Central Oregon (Deschutes and Jefferson counties). Between May 9 –Dec., 2002, an estimated 500 deer died from the virus in the Crooked River Ranch area, near Sisters, Oregon and in the eastern part of the Grizzly Unit. High-density deer populations could have a higher risk for the disease due to the ease of transmission. ODFW staff is encouraging people to avoid providing feed or water stations for deer because these activities may assist in spreading the disease if it is present. There are no known health risks of eating meat from a deer infected with AHD. However, experts recommend thoroughly cooking (at least 165 fahrenheit) any meat from animals from an infected area. ODFW field personnel will be collecting blood samples from recently killed deer to test for exposure to the virus.
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Deer Hair Loss Syndrome (DHLS)
DHLS is a new illness not seen before it was first documented in black-tailed deer in 1995 on Naval Sub base Bangor in Washington. By spring 2002, DHLS had spread south through western Oregon into Jackson and Josephine counties. It is called a syndrome because the exact cause is not known. Deer exhibiting hair loss have large numbers of lice which cause irritation. The typical pattern seen in deer suffering from DHLS includes a darkening of the hair in patches or over large portions of the body, often becoming apparent Dec. – Apr. Hair loss occurs as deer rub, bite, and scratch their hair off causing the appearance of white or yellow patches. As the hair is rubbed off, deer start losing energy reserves and often the coat appears “wet” or in rough condition. Deer can appear emaciated or gaunt, appear slow and lethargic and are often seen biting, licking and chewing their hair, and may have diarrhea. Death can occur, most likely from exposure to the elements. Some deer recover and appear to grow new summer coats. Biologists suspect some deer that appear to recover in summer suffer symptoms again the following fall and perish. ODFW field personnel will be collecting lice and other samples from hunter harvested deer that appear to be suffering from this syndrome.
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Epizootic Hemorrhagic Disease (EHD)
(EHD) is caused by an infection of a virus with symptoms similar to other hemorrhagic diseases like Bluetongue virus and Adenovirus Hemorrhagic Disease. EHD only affects ruminants, which are hoofed, even-toed animals. Humans and domestic pets such as cats and dogs cannot be infected with the disease. White-tailed deer are particularly susceptible, but it can affect black-tailed deer and mule deer as well.
EHD was confirmed in deer in the Roseburg area of southwestern Oregon in the summer of 2014. ODFW believes this is the first time EHD has been documented in wildlife in Oregon.
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Pneumonia in Bighorn Sheep (Pasteurellosis)
Pasteurellosis is a respiratory disease impacting bighorn sheep throughout the west and has been implicated in two recent bighorn die-offs in NE Oregon. Biologists believe both outbreaks were the result of bacteria in the pasteurella family, which are deadly to wild bighorn sheep. Pasteurellosis can lead to significant all-age mortality, diminished ewe fertility, and low lamb survival for many years. Bighorn sheep with pasteurellosis may exhibit noticeable signs including coughing, nasal discharge, and difficulty climbing or running. The best treatment for this disease is prevention. ODFW currently manages bighorn populations to avoid exposure to the disease by preventing wild sheep from contacting domestic sheep or goats that may carry the disease.
Population Management and Impacts to Hunters
Persistent disease or epidemics can have impacts to wildlife populations and hunters. The most notable impact is a reduction in overall population numbers and the resulting reductions in hunting or viewing opportunities. Population reductions can occur as a result of the disease itself, or as a result of the management that may be required to contain or control a particular disease. The disease may have more subtle effects such as predisposing animals to predators or inclement weather, or causing low recruitment and reduced overall population levels through time. There also may be regulation changes as a result of disease and disease prevention. In response to concerns for Oregon’s wildlife, the Fish and Wildlife Commission adopted rules in fall 2002 that banned importation of live animals in the deer family (except for reindeer), and in June 2003 adopted regulations governing importation of carcasses of members in the deer family. Although this may be an inconvenience for Oregon hunters traveling to other states, it is a measure designed to protect Oregon’s wild deer and elk.
Wholesomeness of the Meat
With the exception of TB, none of the diseases discussed above represent a significant threat to human health. Further, TB and CWD have not been found in wild deer or elk in Oregon. However, general caution should be used when field dressing game animals and handling game meat. ODFW offers the following tips for hunters taking to the field this fall:
- Normal cooking will kill almost all disease-causing germs. Be sure to cook your game meat properly to at least 165 degrees Fahrenheit.
- Avoid cross-contamination between entrails and raw meat, and between raw and cooked meats. Cutting boards, knives, wiping cloths, sponges and other tools should be cleaned and washed between uses. Common household bleach mixed 4 parts bleach to 6 parts water can effectively sterilize most utensils.
- Always check for any abnormalities when field dressing an animal that has been killed. Tuberculosis typically is seen as nodules or lumps in the lungs, on the chest wall, and in the lymph nodes between the lungs and around the intestines. If hunters see abnormalities when field dressing a deer or elk, please place a sample in a clean plastic bag and contact the local ODFW field office as soon as possible.
- CWD is associated with brain, spinal column, and lymphoid tissues. Boning meat and trimming all lymph nodes and fatty tissues from the meat should effectively avoid cross contamination.
- Plastic or rubber household cleaning gloves should be worn when field dressing, and when removing antlers from the skull. All saws and knives should be cleaned using a solution of common household bleach mixed 4 parts bleach to 6 parts water.
What should Hunters Do?
Avoid shooting an animal that appears sick, is acting unusual, or is exhibiting any of the symptoms described above. If you observe such an animal, document the location of the animal and call your local ODFW office as quickly as possible. Additional information on these diseases can be obtained at your local department office or found on the Wildlife Health Program website.