David Robson at the BBC:
It is more than 150 years since scientists proved that invisible germs could cause contagious illnesses such as cholera, typhoid, and tuberculosis. The role of microbes in these diseases was soon widely accepted, but “Germ Theory” has continued to surprise ever since – with huge implications for many apparently unrelated areas of medicine.
It was only in the 1980s, after all, that two Australian scientists found that Helicobacter Pylori triggers stomach ulcers. Before that, doctors had blamed the condition on stress, cigarettes and booze. Contemporary scientists considered the idea to be “preposterous”, yet it eventually earned the Nobel Prize for Physiology or Medicine in 2005.
The discovery that the human papillomavirus can cause cervical cancer proved to be similarly controversial, but vaccines against the infection are now saving thousands of lives. Scientists today estimate that around 12% of all human cancers are caused by viruses.
We may be witnessing a similar revolution in our understanding of Alzheimer’s disease.