The Jaded Jedi

Journal and General Musings

The lucky devils with contagious cancer.

20/01/2015

Tasmanian Tiger

Tasmanian Tiger

In the mid 1930’s the last captive example of the Tasmanian tiger died in an Australian zoo. Ironically, had it not been in the zoo in Hobart it may have survived as it appears to have died from exposure.

The animal was unable to handle to low temperatures and had been ‘locked out’ unable to seek its natural refuge.

Some doubt continues as to whether the Tasmanian Tiger (Thylacine) is extinct in the wild. Several reports of sightings have been reported in remote parts of the island, but none have been documented with supporting evidence. It is fair to say the last photographed sighting was in 1936 with the death in captivity in Hobart zoo.

As we all know Australia is a country noted for its wildlife, particularly its marsupials. Everyone has an immediate thought of kangaroos (not unreasonably given it is nearly universally the symbol of Australia). However, there are plenty of other animals unique to this island continent. The potential loss of the Thylacine is still deeply regretted among Australian naturalists, not least because the species was effectively hunted out of existence.

The Tasmanian Devil

The Tasmanian Devil

However, one of the most endearing creatures in Australia, also native to Tasmania is fighting a battle of an altogether different kind.

This charming and feisty marsupial (about the size of a spaniel) is suffering from a form of cancer which is decimating the natural population reducing its numbers by 50% in the most densely populated regions.

The condition first came to light in the mid 1990’s although there is some suggestion ut may have predated this by a few years in an unreported state. However, it is fair to say this emblem of Tasmania and unique creature to Australia is fighting for its survival. The most interesting aspect of this tragedy is the nature of the condition afflicting the Devils.

Facial Tumour Disease

Facial Tumour Disease

The disease ravaging the population is a form of facial cancer. Once infected, the animal develops a series of growths around the face and mouth. Once these start to develop the animals fate is sealed with the tumours ultimately growing to the extent that they prevent the animal from feeding and it starves to death.

Although work is focusing on a vaccine, there is no current treatment or preventative medication to alleviate the condition or control its spread. So what has caused such an immediate and unforgiving progress of the disease? Researchers were initially of the view that the cancer may be environmental, although this was largely excluded as a transfer mechanism between animals. Next the possibility of a virus or bacteria spreading the illness was investigated. However, this proved equally unconvincing as an answer.

The most unusual (and when a human population is considered the most scary) transmission route was left – the cancer is contagious being passed from one animal to the other by direct contact.

The example of a cancer passed in this way is exceptionally rare. The only other known case being a form of canine venereal cancer. As a result it has attracted significant research in part to prevent a similar mechanism ever developing in human cancers and partly due to its extremely exotic an novel pathology.

As can be seen from some footage I was lucky enough to capture earlier this week, this is a quiet and shy animal around humans. However, that is far from the case with other Devils. In fact it was the violent fights and disputes between these animals that gave rise to their name. The sounds made when disputing territory or food was so outlandish it was felt that it could only be demonic in nature. Luckily, that characteristic led to a discovery and working hypothesis as to how the cancer is being spread.

Tasmanian Devil Fight

Tasmanian Devil Fight

During the disputes between animals it is not uncommon for one animal to bite the other around the mouth or face. Scientists believe it is this action which is key to the transmission of the cancer. In effect, small fragments of the cancer in an infected animal are passed via the bite and graft into the new host spreading the disease among the population. A transmission route which is otherwise unique among animal cancers. So in some senses the last case identified is still spreading the same tumour material.

However, here is where the Tassie Devils are lucky. Thay have an interesting cancer. In fact it isn’t just interesting it’s unique. They are also small cuddly and endearing which means they are already high on the researchers lists. Then came ‘Cedric’ a west coast Devil who catapulted the study to the top of so many research teams that perhaps they stand a chance at finding a cure.

In simple terms Cedric lasted a lot longer than he should have. The disease took longer to take hold and longer to progress. The only identifiable difference was that Cedric was from the west of the island – most devils came from the east. This led to a project to map the genome of the devils and compare the western and eastern populations. Surprisingly, whilst there is only one species, there have been proven to be significant genetic differences between animals from the west of the island when compared to those from the east.

Now the genomes are mapped and populations of healthy animals have been isolated to ensure that there are some animals (mainly in zoos and sanctuaries) to continue the species and ensure they don’t share the fate of the Thylacine.

Combined Sciences

Combined Sciences

That was the point at which the devils became lucky. Their condition is now of interest to geneticists, zoologists, oncologists, biologists and anthropologists. In addition, the capacity to spread cancer by physical contact (and how to prevent such events in the human world) are critically important to wider medical study. Suddenly, everyone wants to study Tasmanian Devils and find a cure to this hideous condition.

The news so far is mixed, although there is no vaccine, isolating healthy populations does appear to be working. In addition, some early studies suggest that some of the western devils may have greater protection and a very slow progression of the disease. Whilst it isn’t exactly remission, some infected devils may run their natural life span before the facial tumours progress to a fatal stage. All this may buy the animals time.

Progress in this area is also providing interesting research in human medicine. Possible progress in the fields of oncology, neurology and virus transmission can be tracked back to this work. The sad thing is that this effort is still based on the fact that these animals are cute, furry, friendly and endearing with an undeniable charm. I wonder how much we would have bothered if this disease impacted on rattle snakes, crocodiles, skunks or other less engaging species.

I hope Australia and the world can find some way to defeat this condition in a truly beautiful and charming animal. I hope we can also ask ourselves how much there may be to learn from similar study of less photogenic and outwardly attractive animals.

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