Statistics
In the 20s, the U.S. Public Service, the precursor of the NIH and the CDC, decided that the pellagra epidemic in this country that killed tens of thousands of farmers was an infectious disease, transmitted very much like AIDS, by sex and poor hygiene. Until a doctor...a pharmacologist from New York, finally discovered it was a nutritional deficiency that turned out to be a vitamin B deficiency.
Most recently we are saying that cervical cancer in women is due to human papillomavirus. Ten years ago, it was herpes virus, you remember. There was just a study at Berkeley. It studied 400 female students on the Berkeley campus. 250 were papillomavirus positive. In reality, 50% of all women in this country have these papillomaviruses and men have them too, and the incidence of cervical cancer is totally independent of it. The percentage of women with cervical cancer with and without papillomavirus reflects exactly the percentage of papillomavirus in this country. No evidence whatever.