From New Scientist magazine, Oct. 2009
Twentieth century medicine was phenomenally successful at developing vaccines and antibiotics to fight infectious diseases, taming ancient scourges such as smallpox, tuberculosis and typhoid. In the 1960s and 70s, the prevailing view was that all diseases caused by microorganisms would soon be conquered, leaving only those caused by genetics, unhealthy lifestyles or ageing.
That idea now seems naive, not least because of the rise in antibiotic resistance. And there's another reason that no one even considered back then. A growing number of diseases that were thought to be down to genetics or lifestyle turn out to have an infectious origin.
Take stomach ulcers. Long thought to be triggered by stress, it emerged in the 1980s that many cases are caused by a bacterium called Helicobacter pylori. Now a short course of antibiotics is all that's needed to cure the condition, and in the west stomach ulcers are on the decline.
Since then, researchers have unearthed the unexpected infectious origins of several other diseases. In some the explanation is unique, but in others common mechanisms are at work.
For example, several autoimmune diseases arise because infection with a microbe triggers an immune attack, which cross-reacts with similar molecules from the host, causing the immune system to attack human tissues. And several cancers may be caused by viruses, sometimes because they insert themselves into our DNA and disrupt the genes that usually stop cells multiplying out of control.
The idea that lifelong conditions such as type 1 diabetes and obesity could be caught as easily as a cold is spine-chilling. Yet it raises the tantalising possibility that they could be treated with antibiotics or antiviral drugs, or possibly even prevented with a vaccine. So which of the following illnesses will be next to go the way of stomach ulcers?
6 diseases that may have an infectious etiology:
1) Is obesity caused by a chicken virus?
2) Are the Coxsackie B enteroviruses (CBV) responsible for diabetes?
3) Is schizophrenia a result of a parasite that lurks in cat feces?
4) Is the mouse mammary tumour virus the root cause of breast cancer in women?
5) Can the streptococcus bacterium lead to OCD?
6) Is a virus similar to the xenotropic murine leukaemia virus (XMRV) a cause of prostate cancer in men?
Thoughts?