The other day after giving a lecture on emerging infectious diseases, I was thinking (again) about how the causes of disease emergence are mostly social. Actually, a former student, who is a retired biochemistry professor, suggested that I use the term “catalysts of emergence.” That was true in the original 1992 Institute of Medicine of Medicine report, and is true in the 2003 update by the IOM, “Microbial Threats to Health: Emergence, Detection, and Response” (National Academy Press) See nap.edu for online edition. The catalysts listed are 1) microbial adaptation and change; 2) human susceptibility to infection; 3) climate and weather; 3) changing ecosystems; 4) economic development and land use; 5) intent to harm; 6) technology and industry; 7) international travel and commerce; 8) breakdown of public health; 9) war and famine; and 10) lack of political will.

The argument is lengthy for a few of these catalysts, but each of these has social and biological factors underlying them. Yes, the catalysts are, in part, biological, but underlying the biology is behavior and society. Our task, in order to understand health and disease, is to understand the ties and intricate linkages at numerous scales between individual behavior, society, molecular structure, cellular processes, and microbial pathogenesis. It is very hard.