-Increased infectious and parasitic diseases with increased human population density.
-Agricultural production ore stationary way-of-life.
-Increased contact infected animals and human waste. (i.e. zoonoses, vectors and vehicles of transmisstion).
- 2nd transition modern times with control of infectious diseases and rise in chronic and degenerative diseases.
-Antibiotics and vaccines in last century.
-Diseases of wealth, affluence, and sedentary inactivity in developed nations.
- 3rd transition present globalizing disease ecology leading to the re-emergence of infectious disease
-Rapid increases in spread of MDRTB, HIV, SARS, Pandemic Flu, cholera.
-Rapid resistance to treatment (antibiotics).