Nov. 5 (UPI) -- An infectious cancer has spread from mussels living along the coast of British Columbia to related mussel species in Europe and South America.
The reports of the disease's spread, detailed today in the journal eLife, suggest humans are playing a role in the cancer's proliferation across the globe.
Scientists knew mussels in disparate parts of the world were being harmed by similar cancers but, until now, researchers weren't sure whether the diseases were transmissible.
Most cancers are caused by DNA mutations that trigger uncontrolled cell growth. Most cancer cells don't travel from one individual to the next, but a few species have been affected by infectious cancers.
"Tasmanian devils, dogs and bivalves have all developed cancers that can spread to others, acting more like a pathogen or parasite," Marisa Yonemitsu, research technician at the Pacific Northwest Research Institute in Seattle, said in a news release.
For the new study, Yonemitsu and her colleagues analyzed the DNA of three different mussel species affected by cancer: Mytilus trossulus, a species native to British Columbia; M. edulis, from France and the Netherlands; and M. chilensis, a species found along the coasts of Chile and Argentina.
Researchers were surprised to find the cancer cells collected from mussels in Europe and South America were genetically nearly identical to the cancer cells from Mytilus trossulus.
Authors of the new research paper suggest infected mussels are being carried across the world by international shipping vessels, bringing the cancerous mussels into contact with new bivalve populations.
"Since Mytilus mussels do not live in the equatorial zone, it would have been nearly impossible for them to have spread this cancer between South America and the Northern Hemisphere on their own," said Michael Metzger, assistant investigator at the Pacific Northwest Research Institute.
Researchers plan to conduct followup studies to better understand how cancerous cells from one species come into contact with and infect cells from another species.