Contagious Cancer and Its Implications

Cancer, long thought to be non-contagious, can in extreme cases migrate within a species. In Tasmania, large populations of the Tasmanian devil have been infected by the devil facial tumor disease (DFTD). Recent reports show an 80% reduction of devil sightings throughout Tasmania (their only natural habitat). Tests conducted reveal the animal’s aggressive behavior within its species spreads infected tissues through byte marks. Still certain questions remain:

Why has the spread of DFTD not been detected before in the Tasmanian devil?
Why have these malignant tumors not spread among the species in all parts of the country?

DNA analysis has confirmed over-hunting and the introduction of dingoes on the island/nation has decimated the devil population to the point where animals breeding in certain parts of the country do not have the same genetic diversity that protects other devils. With a smaller gene pool to draw upon, Tasmanian devils affected by the disease have compromised immune systems not capable of recognizing foreign cells allowing tissue to survive in another host.

To counteract this deficiency, breeding programs have now been implemented to mix different populations of devils. Although this technique shows promise, it cannot help animals with similar genetic dispositions that we do not catch in time.

Lobster shell disease is a condition where the lobster develops a bacterial anomaly in the porous shells which supposedly does not infect the meat. Despite this, lobsters with the condition are not marketed or at least that is the theory. For years, southern New England has been plagued by this disease. The threat now appears to be moving north into Main’s coastal region. Although no confirmed linkage to over-fishing has been made, the possibility of less resistance to certain diseases due to decreased genetic diversity cannot be ignored.

Certainly the effects of pollution, habitat loss in breeding waters and other factors must be considered but the ability to resist strain on a species becomes even more critical without sufficient genetic variation. Re-stocking estuaries is possible as in the case of oysters but not a full solution in itself. Salmon are particularly vulnerable due to encroachment by man. Often dams and rerouted waterways disrupt migratory paths where salmon are known to spawn in rivers. The problem has become so bad that populations of salmon from hatcheries must be released to mix with wild salmon periodically in northwestern North America.

While research is being done to explore the risks of over-fishing and over-hunting, the food chain still continues its normal cycle. What goes around comes around. Lobster shell disease may not be as bad as it appears but it could be a sign of possible future mutations. With bacteria and other parasites evolving at an alarming pace, one should think twice whether that 3-pound lobster is really worth the cost.

Robert Haskell is a writer for <a href=""></a> on health related and business news topics.

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