Amazing stuff! Cancer is history (soon)!
"The mystery disease that’s been plaguing the brown bullhead catfish (Ameiurus nebulosus) in a lake straddling the Canada–US border has been identified as a type of transmissible cancer — a phenomenon rarely seen in the animal kingdom.
Surveys have suggested that the disease, a type of melanoma that manifests as inky black skin lesions, affects around one-third of the lake’s catfish population. But it appears in both young and old individuals, suggesting that it might not cause a rapid death."
"Researchers have discovered a contagious cancer in catfish — just the fourth example of tumour cells that spread naturally from one animal to another. ...
The skin lesions, a form of melanoma, are inky black and sometimes crusty, with some fish displaying “tumours on top of tumours”, and can spread to the brain, liver and other organs ... But the health effects are unclear, because the tumours appear in young and old mature fish. “We don’t have evidence of a huge age cliff that suggests it’s killing the fish,” ... "
"... In fact, the first documented observation of the catfish cancer may be from Massachusetts, in the journals of Henry David Thoreau.
In July of 1852, Thoreau was on the Concord River and wrote, “one of these large pouts [catfish] had a very large velvet-black spot, which included the right pectoral fin; a kind of disease I have often observed on them.”
Six years later, Thoreau again wrote in his journal: “I see a pout this afternoon in the Assabet”—a tributary of the Concord River— “lying on the bottom, near the shore, evidently diseased. He permits the boat to come within two feet of him. Nearly half the head, from the snout backward diagonally, is covered with an inky-black kind of leprosy, like a crustaceous lichen.” ..."
From the abstract:
"Since 2012, brown bullhead catfish (Ameiurus nebulosus) in a lake that spans Vermont, USA, and Quebec, Canada, have shown a high rate of melanomas, suggesting a causal contaminant or contagion.
We tested the hypothesis that this affliction represents a clonally transmissible cancer, a rare phenomenon in which cancer cells themselves spread between individuals, behaving more like parasites than conventional tumours.
Whole-genome sequencing of tumour and matched non-tumour host tissues revealed that tumour mitochondrial and nuclear genomes are more closely related to each other than to their hosts or unaffected fish.
Hundreds of thousands of genetic variants are shared among tumour samples but are absent from host fish, vastly exceeding levels seen in conventional cancers. These findings indicate that melanoma in these brown bullheads represents the fourth documented type of naturally occurring transmissible cancer in animals, after dogs, Tasmanian devils and several bivalve species. This raises important questions about the cancer’s origin, the mode of transmission and the long-term impact on fish populations."
Rare contagious cancer discovered in wild catfish "Transmissible tumours have been found in only a few types of animal, but there might be many more out there."
More Like Parasites Than Tumors: Vermont Scientists Discover Transmissible Cancer in Catfish (original news release)
Fig. 1: Brown bullhead sampling, example melanistic lesions and hypotheses of tumorigenesis.
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