Q.1 What is the difference between epidemiology of 19th century  and 21st century

Answer: Epidemiology in the 19^th century – focus on acute infectious disease. Such as Virulent, highly contagious microorganisms – measles, yellow fever, smallpox, typhoid, cholera.It was a prototypical for public health with a widespread impact and inherently social (external threat)

However, 21st century Epidemiology is expanding beyond the original rationale focusing on 

•          Non-contagious diseases

•          Indirect societal involvement

•          Mass disease

•          Opportunity for prevention

Q.2 What do you mean by epidemiology of behavior?

Answer: Epidemiology of behavior  is proposed to specify a systematic sequence of studies on health-related behaviors, leading to evidence-based interventions directed at populations. The phases are: 

1—establish links between behaviors and health; 

2—develop measures of the behavior; 

3—identify influences on the behavior; 

4—evaluate interventions to change the behavior; 

5—translate research into practice.