INVESTIGATING AN OUTBREAK
Public health department staff responsible for reviewing disease report
forms notice that the number of forms for shigellosis seems higher than
usual this week. Someone from a nursing home calls to report several cases
of pneumonia among its residents. Is the number of cases in either of these
situations actually higher than usual? What should be used to estimate
“usual?” If it is higher than usual, should the health department staff call
the situation a cluster, an outbreak, an epidemic? Is a field investigation needed? What criteria
should they use to decide? And if they decide that a field investigation is indeed warranted, how
do they go about conducting such an investigation? These and related questions will be
addressed in this lesson.