A deadly cancer that develops in Tasmanian devils appears to reduce the chances of infected individuals interacting with others, which could prevent the disease from causing these animals to become extinct.
The contagious cancer known as Devil Facial Tumor Disease (DFTD) is spread through bites and causes tumors in the jaw. It can be fatal in less than a year. Tasmanian Devils (Sarcophilus harrisii) are aggressive animals that often fight for mate and food, which can worsen the spread of DFTD. The disease has wiped out more than 80 percent of the population in the past 20 years.
This cancer can make it difficult for Tasmanian devils to feed as the tumors tend to displace an animal’s teeth. “Sick animals can isolate themselves from other people to save energy and recover,” says David Hamilton of the University of Tasmania in Australia.
To see if this affects the spread of DFTD, Hamilton and his team tied 22 wild Tasmanian devils with tracking collars and then released them into their natural habitat. The collars detect when an animal is less than 30 centimeters away from another collar animal. In front of the collar, the Tasmanian devils were screened for symptoms of DFTD and captured every month to monitor the prevalence of the disease and tumor growth.
The team found that as their tumors grow, the infected Tasmanian devils are less likely to interact with others. “People with very large tumors do not come into contact and bite many other devils, so they have very little opportunity to transmit the disease,” says Hamilton.
Three out of 22 Tasmanian devils observed showed symptoms at the start of the study. Six months later, almost half of the population was infected with DFTD. “We believe those who are spreading it are likely those who are in the earlier stages of infection,” says Hamilton. At this point, devils with the tumor are still fit enough to fight and spread the disease.
This disease nearly brought these animals to extinction, but the Tasmanian devils are starting to adapt to the threat. “DFTD itself is not going to make this final push towards extinction,” says Hamilton. “However, human impacts on their environment could occur and we must work hard to prevent it.”