Research and Technology
Modern health care could be said to date from the development of a smallpox vaccine by Edward Jenner in 1796, although vaccines did not become an important part of public health until the twentieth century. The scientific base for the "germ theory of disease," which has been a central part of medical thinking and practice, was laid by Louis Pasteur and Robert Koch in the nineteenth century with the discovery of bacteria. The same discovery gave an added impetus to public health measures improving the quality of water supplies and providing for waste disposal, although these practices had been known to reduce illness for a very long time. Although the first antibiotic was discovered in the nineteenth century, and penicillin in 1929, the antibiotic revolution that provided the therapeutic as distinguished from the preventive implementation of Pasteur's findings did not really start until around 1940. Since then, it has largely run its course, as microorganisms have developed resistance to most antibiotics. Staphylococcus, pneumococcus, and tuberculin bacilli have become resistant to almost all antibiotics. Although new vaccines against malaria, hepatitis B, and venereal diseases perhaps remain to be developed, and drugs effective against viruses are in their infancy, the simple germ model of disease has nearly exhausted its potential. Its very success has pushed cancer and cardiovascular diseases to the top of the medical agenda. Newer, more complex models are evolving.
The simple causal germ model, focusing on an external prime and proximate cause, is not adequate even where the germ theory has been established as sufficient and necessary cause. It is not a question of replacing a bad model with a better one, but of supplementing, modifying a model that has proven very useful and will so remain, to improve our understanding where the germ theory is inadequate, in particular where it appears to be irrelevant. We have no reason to believe that all forms of diabetes or astig-