A study confirms that maternal transmission of chronic wasting disease to fawns is possible via different pathways.
One prominent topic covered at the CWD summit is the mechanisms by which the disease is transmitted from one animal to another. Dr. Candace Mathiason at Colorado State University presented what she and her colleagues have learned about maternal transmission of CWD to offspring.
Experiments conducted by Mathiason have used Reeves’ Muntjac deer to study CWD transmission. Initial studies involved 12 CWD-positive females that gave birth to 14 fawns. Although only three fawns lived more than a few days after birth, Mathiason found that all three had prions, the misfolded proteins believed to cause CWD, within 58 months after birth. This demonstrated that maternal transmission of CWD does occur.
Mathiason also studied the presence of CWD in wild mule deer in Rocky Mountain National Park. She found that CWD was transmitted in utero to fetuses from infected does. Later analyses revealed that prions are present in both the amniotic fluid and the placental tissue of CWD-positive deer, suggesting two pathways that offspring may contract the neurological disease. Of note is that prions were found in placental material of deer that showed no clinical symptoms of CWD, such as emaciation, drooling and excessive thirst, drooping ears, and loss of fear of humans. In other words, just because a female deer appears healthy doesn’t mean it can’t transmit CWD to offspring.
Little is known about whether CWD can be transmitted to fawns from the milk of nursing mothers, or if CWD can be transmitted via the seminal fluid from CWD-positive males to females. Mathiason’s future research will look at these questions.
Finally, Mathiason discussed the transmission of CWD across different species. Experiments have shown that brain inoculations of infectious material into domestic cats caused CWD 4-6 years after inoculation. Other lab experiments have found that sheep, ferrets, pigs, rodents and even some monkeys can contract the disease from infected CWD particles.