Question

Which of the following is characteristic of a single exposure common vehicle outbreak?

a. Wide range in incubation times for sick individuals

b. There is an exponential increase in secondary cases following initial exposures

c. Long latency period before many illnesses develop

d. The epidemic curve has a normal distribution when plotted against the logartihm line

e. Cases include only those who have been exposed to sick persons

Answer 1

d.) The epidemic curve has a normal distribution when plotted against the logarithm of time

As, Single-exposure, common-vehicle outbreaks involve a sudden, rapid increase in cases of disease that are limited to persons who share a common exposure. Additionally, few secondary cases develop among persons exposed to primary cases. A histogram of the outbreak can plot the number of cases by time of disease onset. In single-exposure, common-vehicle outbreaks, a log transformation of the time of disease onset will often take on the characteristic shape of a normal distribution (i.e., a bell curve) with the median incubation time found at the peak of the curve.