Clean water, sewage removal, nutritious food and better standards of living turned formerly “killer” diseases – typhoid fever, scarlet fever, cholera, measles, pertussis and others – into mild childhood diseases. Germs are everywhere, but when you are healthy, you don't contract the diseases as easily and if you do get an infection your body fights it off and you get permanent immunity. World famous researcher Ivan Illich, PhD’s words should be read by all (feel free to forward to others):

The combined death rate from scarlet fever, diphtheria, whooping cough, and measles among children up to fifteen shows that nearly 90% of the total decline in mortality between 1860 and 1965 had occurred before the introduction of antibiotics and widespread immunization. In part this recession may be attributed to improved housing and to a decrease in the virulence of micro-organisms, but by far the most important factor was a higher host resistance due to better nutrition.

In poor countries today, diarrhea and upper-respiratory-tract infections occur more frequently, last longer, and lead to higher mortality where nutrition is poor, no matter how much or how little medical care is available.

The study of the evolution of disease patterns provides evidence that during the last century doctors have affected epidemics no more profoundly than did priests during earlier times. Epidemics came and went, imprecated by both but touched by neither.

References

Illich I. Chapter 1: The Epidemics of Modern Medicine in Medical Nemesis. NY: Bantam Books. 1976.