MADISON — Six fawns in the area of south central Wisconsin where chronic wasting disease has been found in white-tailed deer have tested positive for the disease, according to Department of Natural Resources wildlife health officials. These are the youngest wild white-tailed deer detected with chronic wasting disease (CWD) to date.
Approximately 4,200 fawns, defined as deer under 1 year of age, were sampled from the eradication zone over the last year. The majority of fawns sampled were between the ages of 5 to 9 months, though some were as young as 1 month. Two of the six fawns with CWD detected were 5 to 6 months old. All six of the positive fawns were taken from the core area of the CWD eradication zone where the highest numbers of positive deer have been identified.
“This is the first intensive sampling for CWD in fawns anywhere,” said Dr. Julie Langenberg, Department of Natural Resources wildlife veterinarian, “and we are trying to learn as much as we can from these data”.
“One noteworthy finding is simply the fact that we found positive fawns,” Dr. Langenberg said. “These results do show us that CWD transmission can happen at a very young age in wild white-tailed deer populations. However, we found that the percentage of fawns infected with CWD is very low, in the area of 0.14 percent. If there was a higher rate of infection in fawns, then fawns dispersing in the spring could be much more worrisome for disease spread.”
Dr. Langenberg noted that while the youngest CWD-positive fawns had evidence of disease-causing prions only in lymph node tissue, several of the older CWD-positive fawns had evidence of CWD prions in both lymph node and brain tissues — suggesting further progression of the disease.
“Finding CWD prions in both lymph and brain tissues of deer this young is slightly surprising,” said Langenberg, “and provides information that CWD infection and illness may progress more rapidly in a white-tailed deer than previously suspected. Published literature suggests that CWD doesn’t cause illness in a deer until approximately 16 months of age. Our fawn data shows that a few wild white-tailed deer may become sick from CWD or may transmit the disease before they reach that age of 16 months.”
One of the positive fawns was shot with a doe that was also CWD positive. Information about these fawn cases combined with will help researchers who are studying the age and routes of CWD transmission in wild deer populations. “More data analysis and ongoing deer movement studies should give us an even better understanding of how this disease moves across the landscape”, said Langenberg.
“Thanks to eradication zone hunters who submitted deer of all ages for sampling, we have a valuable set of fawn data that is contributing to our state’s and the nation’s understanding about CWD,” Langenberg said.