*Pic: Christo Baars
First published August 3
The Tasmanian devil cancer, DFTD (devil facial tumour disease), is one of a growing number of new and emerging diseases.
According to Mathieu Giraudeau and Tuul Sepp, both postdoctoral researchers at Arizona State University, human activities in the environment are causing changes that lead to cancer in wild animal populations. In a recent article, published in the journal Research Ideas and Outcomes (RIO), Jody Warren and Brian Martin examine how scientific research into new diseases follows a pathway that focuses on natural causes.
In three case studies examined, DFTD in Tasmanian devils, AIDS in humans and leukemia in Soft-shell clams, human activities that may have caused or promoted the diseases are ignored.
To explain the Tasmanian devil cancer, the main theory pursued assigns responsibility to the devils’ habit of biting each other. Plantation forestry activities, such as habitat destruction and the use of chemicals, have not been explored thoroughly as a possible cause or contributor. Following a pilot study that found flame retardants in devil tissue, toxicology studies were abandoned, notwithstanding calls for more studies.
AIDS in humans is claimed to have been the result of hunters butchering chimpanzees, with a chimp virus getting into a hunter’s bloodstream. Evidence that some polio vaccines used in central Africa in the 1950s were amplified on chimpanzee kidneys, causing the vaccines to be contaminated by chimp viruses and leading to HIV in humans, has been ignored or dismissed.
Soft-shell clams living in polluted environment have a leukemia, claimed to be a new transmissible cancer. Researchers, using the natural causes hypothesis, claim the marine environment in which the clams filter feed ‘are awash with microscopic cancer cells’.
When investigating the origins of a new disease, it is scientifically and socially risky to put nearly all research effort into a single pathway, even when it seems the most likely one. This is especially the case when vested interests can influence research trajectories. Comparing the research programs for a number of new diseases can reveal assumptions and patterns not evident when studying a single disease. This shows the importance of scrutinizing not only disease origins but also the research programs into these origins.
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*Jody Warren and *Brian Martin are researchers at the University of Wollongong