Coronary Heart Disease: Neither Degenerative Nor Man-Made?
In "On to a Fifth Age? How About We Finish the Second?" we discussed a JAMA editorial wherein Dr. Michael Gaziano asserted we may be entering a fifth age of the so-called epidemiologic transition. These transitions are claimed to be changes in the primary causes of morbidity and mortality and Dr. Gaziano opined that we are moving into an era in which obesity and inactivity will drive preventable illness. We discussed the origin of the idea of epidemiologic transitions and questioned whether we'd ever finished the second age which would have required the conquest of infectious diseases.
The so-called third age was supposed to be the "age of degenerative and man-made diseases" but it keeps turning out that many illnesses thought to be due to wear and tear, lifestyle or pollutants actually have an infectious disease process at their core. Now there's growing evidence that coronary heart diseases (CHD) may in many cases have more to do with a number of infections, including influenza, than with lifestyle or the environment.
Here's a link to a letter published in the Reflections section of The Lancet: Infectious Diseases that nicely summarizes the pre-1970 thinking that pointed to infections as the cause of CHD, the subsequent predominating narrative of chronic diseases not being caused by infections, and the new evidence that chronic diseases are in fact often caused by previously undetected infectious processes: "Inflammation as the Cause of Coronary Heart Disease". And here's a link to a written debate about "this nascent field associating chronic diseases with infections" from 2002 with the author of the recent Lancet paper cited above: "Debate on the Paper by Maria Ines Reinert Azambuja & Bruce B. Duncan".
Given the enormous renewed interest in infections as a possible cause of chronic illness and the ease with which scientists can now find traces of bacterial, fungal and viral DNA (or RNA) at the scene of the suspected microbial crime it's fair to assume that we'll be seeing many more such stories in the future.
