Case of Point Source Epidemic

Out of the 75 persons who attended the picnic, 46 subsequently developed gastroenteritis.

Tasks:

1. Calculate the attack rate?
2. Draw an appropriate epidemic curve.
3. Is this a primary or a secondary attack rate?
4. Is this an incidence of prevalence rate?

Solution:

1)      Calculation

Attack rate = number of exposed people infected with the disease divided by the total number of exposed people

Thus attack rate = 46/75 x 100 = 61.33%

2)      Epidemic curve :

3)       It is primary attack rate

4)      It is an incidence rate