Measuring Morbidity: Prevalence and Incidence

Assessment Description
Morbidity is a term used to describe the unhealthy state of an individual (e.g., individual with diabetes) or within a population (e.g., the incidence of seasonal flu). Whereas mortality is the rate of death in population. Both terms are applied in epidemiology at the individual level and across a population. In public health, surveillance plays an essential role. Surveillance is carried out for many reasons, such as monitoring changes in disease frequency or monitoring changes in the levels of risk factors. Much of the information that is obtained about mortality and morbidity comes from surveillance.

For this assignment, examine prevalence and incidence to measure morbidity for a disease. Read the scenario below and complete the assignment as instructed.

Scenario

In Community X (population 20,000), an epidemiologist conducted a prevalence survey in January of 2012 and reported an HIV prevalence of 2.2%. Over the next 12 months, the department of health reported an additional 50 new HIV cases between February 2012 and January 2013. The total population stayed constant at 20,000.

Assignment Instructions

How many people had HIV in January 2012? Present or describe the formula you used to arrive at your answer.
Calculate the incidence rate assuming no HIV-related deaths over the 12-month period. Present or describe the formula you used to arrive at your answer. Be sure to clearly indicate the numerator and denominator used in your calculation and include an appropriate label for the rate.

In a summary of 200-250 words, interpret the results and discuss the relationship between incidence and prevalence. Discuss whether or not the epidemiologist should be concerned about these new HIV infections, assuming a previous incidence rate of 0.5 per 1,000 person-years prior to this updated risk assessment.