Analytical epidemiology is simply the study of determinants of a specific disease for relatively low or high frequency in a given group of people. Analytical epidemiology always seeks to establish whether a particular invention is effective for curing or preventing the disease or if an exposure is a risk factor for the disease in question. Analytical epidemiology is very important in studies of infectious diseases such as tuberculosis (Schoenbach, 1999). Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis. TB is one of the greatest problems in public health. Recent studies have revealed that approximately 8 million people are diagnosed with TB every year with 2 million of this population succumbing to the disease (Cosio, 2005).

With the rising mortality rate in the community due to tuberculosis, the county health department needs to work on establishing the cause of the new cases of tuberculosis among the community members. Observational and experimental epidemiology study designs can be very helpful in the study of tuberculosis in the community. The health department will adopt an experimental epidemiology study design in which the investigators will assign an exposure to the subjects. The study will be used to test the effectiveness of Bacille Calmette-Guerin as a TB vaccine.

The researchers will pick a sample from the community to be used as the study participants. The most preferred subjects for this type of study would be new born babies. The investigators will divide the participants into two groups. One will be given the BCG vaccination at birth while the other group will not receive the vaccination. The investigators will then follow the participants for ten years to establish whether the group that received the BCG vaccine is more resistant to TB as compared to the other group.

Additionally, the health department can also conduct an observational epidemiology study. For observational study, there will be no need for assigning an exposure. The investigators will the observing and measuring the exposures that are already occurring. An observational study can either be a cohort study or a case-control study. In the cohort study, the investigators will identify two study groups. For this study, the researchers will use exposures such as housing characteristics, family size and poverty levels to establish causes of TB in the community. The study will use participants from two separate target area. The first group will include residents from a sparsely populated region in the community that have decent housing with fewer family members per house. The second group, on the other hand, will be recruited from a densely populated area with indecent housing and many family members per household. The study will then investigate TB prevalence in the two target areas.

It is, however, important to note that in the case of an outbreak where the prevalence of TB is already identified then the case-control study is the most proffered. In a case-control study, the investigators identify the specific TB cases and then compare them with another group that was not infected. The objective of such a study is to establish if the cases had a specific exposure that the controls did not. The case-control study design is also fast and cost effective as compared to the cohort study. This can be attributed to the fact that in a case-control study the sample size used is very limited as compared to the cohort study. This type of research can be very effective in determining the causes of tuberculosis in an outbreak (Aschengrau & Seage, 2003).