Case Scenario
The results of a study of the incidence of pulmonary tuberculosis in a village in India and given in the table below. All the persons in the village were examined during the surveys made 2 years apart, and the number of new cases was used to determine the incidence rate.
| Category of Households at first survey | Number of persons | Number of new cases
|
| With culture positive case | 500 | 10 |
| Without culture positive case | 10,000 | 10 |
Task:
What is the incidence of new cases per 1000 person years in households had a culture positive case during the first survey?
Solution:
Incidence is the number of new cases of a disease occurring in a given time period.
Incidence rate = 10/(500 x 2) x 1000
Thus the incidence rate is 10 per 1000 person years.
