Based on the results of the study shown below, the epidemiologist has reason to worry because the incidence rate increased over four times the previous level as shown below:
Prevalence rate is the proportion of persons in a population who have a particular disease or attribute at a specified point in time or over a specified period of time.
Incidence rate is the proportion of new cases of a condition observed within a given period of time.
The number of people who had HIV in January 2012 is calculated as follows:
number of HIV cases = 2.2% × 20000
number of HIV cases = 440 persons
Incidence rate between February 2012 and January 2013 is calculated as follows:
Incidence rate = 50/(20000 - 440) × 1000
Incidence rate = 2.25 per 1000 persons.
Based on the new incidence rate, the epidemiologist has reason to worry because the incidence rate has increased over four times the previous level.
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