1. the difference between epidemiology of 19th century and 21st century are given below:
- Diseases and epidemics of the 19th century included
long-standing epidemic threats such as smallpox, typhus, yellow fever, and scarlet fever. In addition, cholera emerged as
an epidemic threat and spread worldwide in six pandemics in the nineteenth
century.
- epidemiology in the 21st century: the impotence of context, problem-based epidemiology, appropriate technology, epidemiology as a population science.
2. epidemiology of behavior:
Behavioral epidemiology is the branch of
epidemiology that is related with the psychology. In this we can study about the lifestyle and
behaviors of people and how they affect their health conditions. Behavioral disease conditions and disease
re-occurrence depends on the behavior is the range of actions and mannerisms
made by individuals in conjunction with themselves or their environment, which
includes the other systems or organisms around as well as physical environment.
It is the response of the system or organism to
various stimuli or inputs, whether internal or external, conscious or
subconscious, overt or covert, and voluntary or involuntary.