Devil facial tumour disease - AbsoluteAstronomy.com

Devil facial tumour disease (DFTD) is an aggressive non-viral transmissible parasitic cancer

Parasitic cancer

A parasitic cancer or transmissible cancer is a cancer cell or cluster of cancer cells that can be transmitted from animal to animal.They are also known as "clonally transmissible cancers".-Examples in animals:...

—which likely originated in Schwann cell

Schwann cell

Schwann cells or neurolemmocytes are the principal glia of the peripheral nervous system . Glial cells function to support neurons and in the PNS, also include satellite cells, olfactory ensheathing cells, enteric glia and glia that reside at sensory nerve endings, such as the Pacinian corpuscle...

s—that affects Tasmanian devil

Tasmanian Devil

The Tasmanian devil is a carnivorous marsupial of the family Dasyuridae, now found in the wild only on the Australian island state of Tasmania. The size of a small dog, it became the largest carnivorous marsupial in the world following the extinction of the thylacine in 1936...

s. The first "official case" was described in 1996, in Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. In the subsequent decade the disease ravaged Tasmania

Tasmania

Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...

's wild devils, with estimates of decline ranging from 20% to as much as a 50% of the devil population, across over 65% of the state. Affected high-density populations suffer up to 100% mortality in 12–18 months. The disease has mainly been concentrated in Tasmania's eastern half. Visible signs of DFTD begin with lesion

Lesion

A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...

s and lumps around the mouth. These develop into cancerous tumours that may spread from the face to the entire body. The tumours interfere with feeding, and the affected animal may starve to death. At present the population has dwindled 70% since 1996. Numbers as of 2010 show an 80% rate of infection throughout the population. Six females have been found with a partial immunity. Breeding in captivity has begun to try to save the population. It is spread by devils biting each other's heads when fighting over food.

Characteristics

Tasmanian devil cells have 14 chromosomes, while the tumour cells contain 13. Researchers identified the cancer as a neuroendocrine tumor, and found identical chromosomal

Chromosome

A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...

rearrangements in all the cancer cells. The karyotype

Karyotype

A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell. The term is also used for the complete set of chromosomes in a species, or an individual organism.p28...

anomalies of DFTD cells are similar to those of cancer cells from canine transmissible venereal tumour

Canine transmissible venereal tumor

Canine transmissible venereal tumor , also called transmissible venereal tumor , Canine transmissible venereal sarcoma , Sticker tumor and infectious sarcoma is a histiocytic tumor of the dog and other canids that mainly affects the external genitalia, and is transmitted from animal to animal...

(CTVT), a cancer of dogs that is transmitted between canines by physical contact.

Ultimately the idea that cancer cells themselves are an infective agent (the Allograft

Allotransplantation

Allotransplantation is the transplantation of cells, tissues, or organs, sourced from a genetically non-identical member of the same species as the recipient. The transplant is called an allograft or allogeneic transplant or homograft...

Theory) turned out to be correct, with transmission of the disease occurring by biting, feeding on the same material, and aggressive mating. Final confirmation of this came when researcher Anne-Maree Pearse and colleagues found an infected animal that had a chromosomal abnormality in its non-tumorous cells that did not appear in its tumour cells, proving that the tumour cells could not have descended from the animal's own cells. Pearse believes that this may prove vital to the survival of the devils. Since June 2005, three females have been found that are partially resistant to DFTD.

Further research from the University of Sydney

University of Sydney

The University of Sydney is a public university located in Sydney, New South Wales. The main campus spreads across the suburbs of Camperdown and Darlington on the southwestern outskirts of the Sydney CBD. Founded in 1850, it is the oldest university in Australia and Oceania...

has shown that the infectious facial cancer may be able to spread because of low diversity in devil immune genes (MHC

Major histocompatibility complex

Major histocompatibility complex is a cell surface molecule encoded by a large gene family in all vertebrates. MHC molecules mediate interactions of leukocytes, also called white blood cells , which are immune cells, with other leukocytes or body cells...

class I and II). The same genes are also found in the tumours, so the devil's immune system does not recognise the tumour cells as foreign. There are at least nine strains of the cancer, showing that it is evolving, and may become more virulent. The strains may also complicate attempts to develop a vaccine, and the mutation of the cancer may mean that it could spread to other related species, like the quoll

Quoll

The quoll, or native cat, is a carnivorous marsupial native to mainland Australia, New Guinea and Tasmania. It is primarily nocturnal and spends most of the day in its den. There are six species of quoll; four are found in Australia and two in New Guinea...

.

In a paper published in the January 2010 issue of Science
Science (journal)
Science is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....

, an international team of researchers announced that devil facial tumour disease likely originated in Schwann cell

Schwann cell

s, a type of cell

Cell (biology)

The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

found in the peripheral nervous system

Peripheral nervous system

The peripheral nervous system consists of the nerves and ganglia outside of the brain and spinal cord. The main function of the PNS is to connect the central nervous system to the limbs and organs. Unlike the CNS, the PNS is not protected by the bone of spine and skull, or by the blood–brain...

that is essential for the functions of nerve cells in the peripheral nervous system

Peripheral nervous system

. The researchers sampled 25 tumours and found that the tumours were genetically identical. Using deep sequencing

RNA-Seq

RNA-seq, also called "Whole Transcriptome Shotgun Sequencing" and dubbed "a revolutionary tool for transcriptomics", refers to the use of high-throughput sequencing technologies to sequence cDNA in order to get information about a sample's RNA content, a technique that is quickly becoming...

technology, the team profiled the tumours' transcriptome

Transcriptome

The transcriptome is the set of all RNA molecules, including mRNA, rRNA, tRNA, and other non-coding RNA produced in one or a population of cells.-Scope:...

, the set of genes that are active

Transcription (genetics)

Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...

in tumours. It closely matched that of Schwann cells. The genetic markers identified by the team will enable veterinarians to more easily distinguish DFTD from other types of cancer (a malady to which devils are unusually susceptible) and may eventually help identify a genetic pathway that can be targeted to treat it.

Due to the decreased life expectancy of the devils due to DFTD, they have begun breeding at younger ages in the wild, with reports that many only live to participate in one breeding cycle. A study has suggested that Tasmanian devils have changed their breeding habits in response to the disease. Females previously started breeding at the age of two, then annually for about three more years until dying normally. Now they commonly breed at the age of one, and die of tumours shortly thereafter. It is speculated that the disease is spread by devils biting each other during the mating season. Social interactions have been seen spreading DFTD in a local area.
It is one of three contagious cancers.

Pathology

Growth of large tumours impedes feeding, and starvation is a common cause of death in affected devils. Organ involvement and additional infections may also be a factor in death, as regional lymph node

Lymph node

A lymph node is a small ball or an oval-shaped organ of the immune system, distributed widely throughout the body including the armpit and stomach/gut and linked by lymphatic vessels. Lymph nodes are garrisons of B, T, and other immune cells. Lymph nodes are found all through the body, and act as...

involvement and systemic metastasis

Metastasis

Metastasis, or metastatic disease , is the spread of a disease from one organ or part to another non-adjacent organ or part. It was previously thought that only malignant tumor cells and infections have the capacity to metastasize; however, this is being reconsidered due to new research...

is common. The cancer invades the heart.

The tumours are capable of dissolving parts of the skull.

Preservation response

Wild Tasmanian devil populations are being monitored to track the spread of the disease and to identify changes in disease prevalence. Field monitoring involves trapping devils within a defined area to check for the presence of the disease and determine the number of affected animals. The same area is visited repeatedly to characterise the spread of the disease over time. So far, it has been established that the short-term effects of the disease in an area can be severe. Long-term monitoring at replicated sites will be essential to assess whether these effects remain, or whether populations can recover. Field workers are also testing the effectiveness of disease suppression by trapping and removing diseased devils. It is hoped that the removal of diseased devils from wild populations should decrease disease prevalence and allow more devils to survive beyond their juvenile years and breed. A study felt that the current system of culling did not impede the disease's spread.

Two "insurance" populations of disease-free devils are being established at an urban facility in the Hobart

Hobart

Hobart is the state capital and most populous city of the Australian island state of Tasmania. Founded in 1804 as a penal colony,Hobart is Australia's second oldest capital city after Sydney. In 2009, the city had a greater area population of approximately 212,019. A resident of Hobart is known as...

suburb of Taroona and on Maria Island

Maria Island

Maria Island is a mountainous island off the east coast of Tasmania. The entire island is a national park. Maria Island National Park has a total area of 115.50 km², which includes a marine area of 18.78 km² off the island's northwest coast. The island is about 20 km in length from...

off the east coast of Tasmania. Captive breeding

Captive breeding

Captive breedingis the process of breeding animals in human controlled environments with restricted settings, such as wildlife reserves, zoos and other conservation facilities; sometimes the process is construed to include release of individual organisms to the wild, when there is sufficient...

in mainland zoos is also a possibility. The decline in devil numbers is also seen as an ecological problem, since its presence in the Tasmanian forest ecosystem

Ecosystem

An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

is believed to have prevented the establishment of the red fox

Red Fox

The red fox is the largest of the true foxes, as well as being the most geographically spread member of the Carnivora, being distributed across the entire northern hemisphere from the Arctic Circle to North Africa, Central America, and the steppes of Asia...

, illegally introduced to Tasmania in 2001. It is believed that Tasmanian devil young would be vulnerable to red fox predation, as they are left alone for long periods of time.

In response to the impact of DFTD on Tasmanian devil populations, 47 devils have been shipped to mainland Australian wildlife parks to attempt to preserve the genetic diversity of the species. The largest of these efforts is the Barrington Tops "Devil Ark"; an initiative of the Australian Reptile Park

Australian Reptile Park

The Australian Reptile Park is located at Somersby on the Central Coast, New South Wales in Australia. It is about North of Sydney, and is just off the Sydney-Newcastle Freeway...

. This project aims to create a set of one thousand genetically representative devils, and is now a major focus of the insurance policy. In addition, the Tasman peninsula

Tasman Peninsula

Tasman Peninsula is located around by road south-east of Hobart, at the south east corner of Tasmania, Australia.-Description:The Tasman Peninsula lies south and west of Forestier Peninsula, to which it is connected by an isthmus called Eaglehawk Neck...

is being considered as a possible "clean area" with the single narrow access point controlled by physical barriers. The Tasmanian Department of Primary Industries and Water

Department of Primary Industries and Water

The Department of Primary Industries, Parks, Water and Environment is the department of the Government of Tasmania responsible for supporting primary industry development, the protection of Tasmania's natural environment, effective land and water management and the protection of Tasmania's...

is experimenting on culling

Culling

Culling is the process of removing animals from a group based on specific criteria. This is done either to reinforce certain desirable characteristics or to remove certain undesirable characteristics from the group...

infected animals with some signs of success.

In 2008, a devil named Cedric was thought to have a natural immunity to the disease, but in late 2008 he developed two tumours on his face. The tumors were removed and officials thought Cedric was responding well until September 2010 when he it was discovered that the cancer had spread to his lungs. He was euthanized upon the discovery. A diagnostic blood test was developed in mid-2009 to screen for the disease. In early 2010, scientists found some Tasmanian devils, mostly in the north-west of Tasmania, that are genetically different enough for their bodies to recognise the cancer as foreign. They have only one Major Histocompatibility Complex

Major histocompatibility complex

, whereas the cancerous cells have both.

At present with the population reduced by 70% since 1996, if a cure is not found then scientists predict they will become extinct by 2035.

A study recommended oocyte banking

Oocyte cryopreservation

Human oocyte cryopreservation is a novel technology in which a woman’s eggs are extracted, frozen and stored. Later, when she is ready to become pregnant, the eggs can be thawed, fertilized, and transferred to the uterus as embryos.-History:Cryopreservation itself has always played a central role...

be used in the conservation effort for Tasmanian devils, as the survival rate of the oocytes in their study was 70%.

In 2010, there was hope that EBC-46

EBC-46

EBC-46 is a natural chemical currently being studied for the treatment of some types of cancer in both animals and humans. The chemical is found in found in seed of the Blushwood Tree and several species from the Fontainea family found locally in the Atherton Tableland of Queensland, Australia...

, a drug which cures facial tumours in dogs, cats, and horses, may be a cure for DFTD.

Vaccination with irradiated cancer cells has not proven successful.

Research published in the Proceedings of the National Academy of Sciences
Proceedings of the National Academy of Sciences
The Proceedings of the National Academy of Sciences of the United States of America, usually referred to as PNAS, is the official journal of the United States National Academy of Sciences...

on June 27, 2011, suggests picking a genetically diverse breeding stock, defined by the genome sequence, for conservation efforts.

In 2011, Principal Investigator David Phalen, (Wildlife Health and Conservation Centre, University of Sydney) and Stephen Pyecroft (Department of Primary Industries and Water in Tasmania) along with Antony Moore and Angela Frimberger (Veterinary Oncology Consultants) were awarded a Tasmanian Government Project Management Grant for their project Investigation into Chemotherapy Agents Effective Against the Tasmanian Devil Facial Tumour.

History

In 1996, a photographer captured several images of devils with facial tumours near Mount William in Tasmania's north-east. At around the same time, farmers reported a decline in devil numbers. Menna Jones first encountered the disease in 1999 near Little Swanport, in 2001 capturing three devils with facial tumours on the Freycinet Peninsula

Freycinet Peninsula

Freycinet Peninsula is a large peninsula in eastern Tasmania, Australia. It is located north of Schouten Island, at . It is the site of Freycinet National Park....

. The devil population on the peninsula decreased dramatically. In March 2003 Nick Mooney

Nick Mooney

Nick Mooney is an Australian conservationist, biologist, writer, wildlife expert, and ecological educator best known for his work with the Tasmanian devil...

wrote a memo to be circulated within the Parks and Wildlife Services calling for more funding for the study of the disease, but the call for funding was edited out before the memo was presented to Bryan Green

Bryan Green

Bryan Alexander Green is a Tasmanian Labor politician and member of the Tasmanian House of Assembly in the electorate of Braddon. In July 2006 he was forced to step down as Deputy Premier and Minister for Economic Development and Resources pending an enquiry into deal made with the TCC...

, then Minister for Primary Industries, Water and Environment. In April 2003, a working group was formed by the Tasmanian Government to respond to the disease. In September 2003, Nick Mooney went to the Tasmanian daily newspaper The Mercury

The Mercury (Hobart)

The Mercury is a daily newspaper, published in Hobart, Tasmania, Australia, by Davies Brothers Pty Ltd, part of News Limited and News Corporation...

, informing the general public of the disease and proposing a quarantine of healthy Tasmanian devils. At the time, it was thought that a retrovirus

Retrovirus

A retrovirus is an RNA virus that is duplicated in a host cell using the reverse transcriptase enzyme to produce DNA from its RNA genome. The DNA is then incorporated into the host's genome by an integrase enzyme. The virus thereafter replicates as part of the host cell's DNA...

was a possible cause. David Chadwick of the state Animal Health Laboratory said that the laboratory did not have the resources needed to research the possibility of a retrovirus. The Tasmanian Conservation Trust

Tasmanian Conservation Trust

Tasmanian Conservation Trust is a Tasmanian based non-profit conservation organisation, formed in 1968.-Further reading:* Armstrong, Lance J.E. . Good God, He’s Green! A History of Tasmanian Politics 1989-1996. Wahroonga, N.S.W., Pacific Law Press. ISBN 1-875192-08-5* Lines, William J. Patriots :...

criticised the Tasmanian Government for not providing sufficient resources to research the disease, and suggested that the DFTD could be zoonotic, posing a threat to livestock and humans. On 14 October 2003, a workshop was held in Launceston. In 2004, Kathryn Medlock found three oddly shaped devil skulls in European museums and found a description of a devil in London Zoo

London Zoo

London Zoo is the world's oldest scientific zoo. It was opened in London on 27 April 1828, and was originally intended to be used as a collection for scientific study. It was eventually opened to the public in 1847...

dying which showed a similarity to DFTD.

A virus

Virus

A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

was initially thought to be the cause of DFTD, but no evidence of such a virus could be detected in the cancer cells. Calicivirus, 1080 poison, agricultural chemicals, and habitat fragmentation

Habitat fragmentation

Habitat fragmentation as the name implies, describes the emergence of discontinuities in an organism's preferred environment , causing population fragmentation...

combined with a retrovirus were other proposed causes. Environmental toxins had also been suspected. In March 2006 a devil escaped from a park into an area which was infected with DFTD. She was recaptured with bite marks on her face, and returned to live with the other devils in the park. She wounded a male and by October both devils were observed to have the disease, which was subsequently transferred to two other devils. This incident helped test the viability of the allograft theory of transmission. In 2006, DFTD was classed a List B notifiable disease under the Animal Health Act 1995. Also in 2006, the strategy of developing an insurance population in captivity was developed. It was reassessed in 2008. A 2007 investigation into the immune system of the devils found that when combatting other pathogens, the response from the immune system was normal, leading to suspicion that the devils were not capable of detecting the cancerous cells as "non-self

Antigen

An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...

". In 2007, it was predicted that populations could become locally extinct within 10 – 15 years of DFTD occurring, and predicted that the disease would spread across the entire range of the Tasmanian devils. This study also predicted that Tasmanian devils would become extinct within 25–35 years.

In 2008, high levels of potentially carcinogenic flame retardant chemicals were found in Tasmanian devils. Preliminary results of tests ordered by the Tasmanian government on chemicals found in fat tissue from 16 devils have revealed high levels of hexabromobiphenyl (BB153) and "reasonably high" levels of decabromodiphenyl ether

Decabromodiphenyl ether

Decabromodiphenyl ether is a brominated flame retardant which belongs to the group of polybrominated diphenyl ethers ....

(BDE209).

In other animals

Transmissible cancer, caused by a clone of malignant cells rather than a virus

Oncovirus

An oncovirus is a virus that can cause cancer. This term originated from studies of acutely-transforming retroviruses in the 1950–60s, often called oncornaviruses to denote their RNA virus origin. It now refers to any virus with a DNA or RNA genome causing cancer and is synonymous with "tumor...

, is extremely rare. The only other known types are canine transmissible venereal tumour (CTVT)

Canine transmissible venereal tumor

, which is passed between dogs via sexual activity and has been known to science for about 100 years, and contagious reticulum

Reticular connective tissue

Reticular connective tissue is a type of connective tissue. It has a network of reticular fibers, made of type III collagen. Reticular fibers are not unique to reticular connective tissue, but only in this type are they dominant....

cell sarcoma

Sarcoma

A sarcoma is a cancer that arises from transformed cells in one of a number of tissues that develop from embryonic mesoderm. Thus, sarcomas include tumors of bone, cartilage, fat, muscle, vascular, and hematopoietic tissues...

of the Syrian hamster, which can be transmitted from one Syrian hamster to another by means of the bite of the mosquito Aedes aegypti
Aedes aegypti
The yellow fever mosquito, Aedes aegypti is a mosquito that can spread the dengue fever, Chikungunya and yellow fever viruses, and other diseases. The mosquito can be recognized by white markings on legs and a marking in the form of a lyre on the thorax...

. CTVT mutes the expression of the immune response, whereas the Syrian hamster disease spreads due to lack of genetic diversity. The mutation of devil facial tumour disease may mean that it could spread to other related species, like the quoll

Quoll

External links

Save the Tasmanian Devil website

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