DDP - Disease Distribution Lesson

Disease Distribution

Earlier we discussed that descriptive epidemiology describes how a disease is distributed in a population of people. We also discussed person, place, and time information. These are the main three categories of descriptive epidemiological clues. The information obtained from descriptive epidemiology can be used to form hypotheses about disease. Hypotheses can be formed to explain why some people got sick and others did not, why the sickness occurred in some places and not others, and why it occurred at some times and not at others.  
Descriptive epidemiological data related to the person can include age, gender, race, ethnicity, risk factors, and other characteristics. The table below shows the percentage or crude prevalence rate of people with depression by age groups and poverty level. What do you notice? What age group has the highest percentage of individuals with depression? What hypothesis can you form to explain the data?

Detail: See full detail for Depression and Poverty Level Links to an external site.

 

Analysis by time is usually conducted to describe trends and detect changes in disease incidence. Some diseases are reported weekly and a comparison of the number of case reports for the current week is made with the previous weeks.   Comparisons are also made between the current timeframe and the same timeframe for previous years. For example, epidemiologists may study the number of flu cases in December of each year for five years to determine a trend.   The chart below displays "data" for four fictional cities - what trends do you notice? Does any city have noticeably less or more cases? Was one year worse for all cities than the others?

Detail: See full detail for Flu Cases in December Links to an external site.

 

Analysis of cases by place can also be displayed by a map.  State and local health departments usually analyze data by neighborhood or county.  Software programs utilizing GIS (Geographical Information Systems) are frequently used to show geographic relationships.  The following map displays information on diagnosis of diabetes by state.  Which states have the highest percentage of diabetes diagnosis among the population?

 

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