Todayโs path rounds are on ๐๐๐ฏ๐ข๐ฅ ๐๐๐๐ข๐๐ฅ ๐ญ๐ฎ๐ฆ๐จ๐ฎ๐ซ ๐๐ข๐ฌ๐๐๐ฌ๐ (DFTD)!
๐๐ก๐๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐๐๐ฏ๐ข๐ฅ ๐๐๐๐ข๐๐ฅ ๐ญ๐ฎ๐ฆ๐จ๐ฎ๐ซ ๐๐ข๐ฌ๐๐๐ฌ๐ is a type of transmissible cancer that has been devastating Tasmanian devil populations in Australia. At one point, over 80% of the Tasmanian devil population was lost due to this disease, making scientists very concerned the species would go extinct. The tumour primarily affects the face, causing large masses and interfering with the devilโs ability to eat. The devils often end up starving to death because they simply canโt cope with the large masses.
๐๐ก๐จ ๐ ๐๐ญ๐ฌ ๐ข๐ญ?
Any Tasmanian devil can get this disease!
๐๐จ๐ฅ๐ ๐จ๐ง, ๐๐ข๐ ๐ฒ๐จ๐ฎ ๐ฌ๐๐ฒโฆ ๐ญ๐ซ๐๐ง๐ฌ๐ฆ๐ข๐ฌ๐ฌ๐ข๐๐ฅ๐ ๐ญ๐ฎ๐ฆ๐จ๐ฎ๐ซ?
You bet I did! This type of tumour is incredibly rare, and not a whole lot is known about them. In fact, there are only three known mammalian transmissible tumours: DFTD, a canine tumour (probably the subject of a future post!) and a hamster tumour. This particular tumour is spread when a devil bites another, and introduces tumour cells into the bite wound.
๐๐ก๐๐ญ ๐๐๐ฎ๐ฌ๐๐ฌ ๐ข๐ญ?
As I said, not much is known about transmissible tumours in general. However, the scientific community is working hard to try and understand them! One of the biggest questions researchers have is โhow do the tumour cells escape the immune system?โ
Normally when foreign cells are introduced into the body, the body produces an ๐ข๐ฆ๐ฆ๐ฎ๐ง๐ ๐ซ๐๐ฌ๐ฉ๐จ๐ง๐ฌ๐ to kill the cells. You may have heard of this concept in relation to organ transplant rejection. In DFTD, cells from another devil are directly introduced into a wound, which would normally stimulate the immune system. However, this does not occur, allowing the tumour cells to proliferate! Current research suggests that the tumour cells have reduced numbers of ๐ฆ๐๐ฃ๐จ๐ซ ๐ก๐ข๐ฌ๐ญ๐จ๐๐จ๐ฆ๐ฉ๐๐ญ๐ข๐๐ข๐ฅ๐ข๐ญ๐ฒ ๐๐จ๐ฆ๐ฉ๐ฅ๐๐ฑ ๐ฆ๐จ๐ฅ๐๐๐ฎ๐ฅ๐๐ฌ on their surface, which are molecules that help the molecules recognize a foreign cell. Without these molecules, the immune system never gets the โsignalโ to destroy the invading cells. Crazy!
๐๐ข๐ฅ๐ฅ ๐๐๐ฌ๐ฆ๐๐ง๐ข๐๐ง ๐๐๐ฏ๐ข๐ฅ๐ฌ ๐๐ ๐จ๐ค๐๐ฒ?
There is some interesting research going on that is tracking the DNA of Tasmanian devils, and they have found some interesting results! They have shown that there have been evolutionary changes in Tasmanian devils, with increased expression of genes related to immune function. This suggests that the devils have evolved to better handle the disease, in just 5 generations of tracking! In fact, there have been reports of devils having their tumours shrink and even disappear, which is amazing and gives researchers a lot of hope that the species will survive into the future. Go devils go!
๐๐ก๐จ๐ญ๐จ๐ฌ
1-5) Examples of devils with DFTD!
๐๐จ๐ฎ๐ซ๐๐๐ฌ
McCallum, H., Patton, A.H. Tasmanian devils look set to conquer their own pandemic. The Conversation, 2020.
Tasmanian devil facial tumour diseases. University of Cambridge Transmissible Cancer Group.
McCallum, H. Tasmanian devil facial tumour disease: lessons for conservation biology. Trends in Ecology and Evolution, 2008.
Photo 1 courtesy of Wikimedia Commons.
Photos 2-4 courtesy of Rodrigo Hamede.
Photo 5 courtesy of Hamish McCallum.
