Quantitative studies are those that rely on measures that can be represented by discrete numbers, such as age, weight or body temperature. Epidemiological studies too can be quantitative in nature. A quantitative epidemiological study can be broadly classified as ‘observational’ or ‘experimental’. It depends upon the extent of intervention by the researcher in the subject’s exposure or actions.
In the last few decades, after the discovery of penicillin, a large number of these diseases have been controlled or eliminated. However, infectious diseases have a tendency to recur in a different population or region than before. This phenomenon is termed as emerging infectious diseases (EID).
Serological and molecular markers are new diagnostic approaches that offer rapid, sensitive and more accurate diagnostic results. Molecular markers are specific short sequence of DNA or RNA.
Moreover, they also show probable high risk areas in the future epidemics. These models are based on previous trends of incidents and climate factors. Thus they allow for better prediction of disease incidents or outcomes.
Epidemics of infectious diseases arise due to spread of the disease across individuals. It spreads within a geographical region over a period of time. When they spread at global level, it is referred to as pandemic. An infectious disease originates at a particular point.
Epidemiology of infectious diseases often require geographical information. Both spatial and temporal factors of a population can affect disease spread.
Descriptive analysis of epidemiological data includes hypotheses development. This is based on variability of disease outcome rates with demographic variables. On the other hand, analytical epidemiology determines cause or mode of disease epidemic outbreak.
Descriptive epidemiology refers to analyzing the existing trends of a disease epidemic. The study is conducted with respect to time, place and persons (Aschengrau and Seage, 2013).