1. Making an epidemic curve (epicurve)
Preben Aavitsland
(with a lot of help from Katarina Alpers, RKI)

2. The epidemic curve Time components of an outbreak Shows
Start
End
Duration
Peak
Outliers
Helps to form hypotheses on
Route of transmission
Probable exposure period
Incubation time

3. The epidemic curve

4. The epidemic curve Histogram X-axis = time Y-axis = number of cases
Area proportional to number
No space between columns
One population
X-axis = time
Start before epidemic, continue after
Interval < 1/4 of incubation period
Y-axis = number of cases
Usually one square = one case
Easy to make in Excel

5. Point source 20 15 10 5 No of cases Time Duration ~ Incubation time
Einmalige Exposition+gemeinsame Quelle
Time
Duration ~ Incubation time

6. Continous source 20 15 10 5 No of cases Weeks 1 4 7 13 16 19 22 25 285 10 15 20 1 4 7 13 16 19 22 25 28 31 34 37
No of cases
Weeks
Mean IP

7. Intermittent source No of cases Time (days) 10 9 8 7 6 5 4 3 2 1 1 2 31 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
Time (days)

8. Human to human transmission
No of cases 10
Generation
time 5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
Zeit

9. Probable exposure time
No of cases
Median incubation time
(Intervall between first and last disease onset) 2 15 3 10 5
Punktquelle 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
Time 1
Probable exposure time
50% %
Median onset time

10. Probable exposure period
No of cases 20 18
maximum incubation time 16 14 12 10
minimum incubation time 8 6 4 2 1 3 5 1 2 7 3 4 9 5 11 6 7 13 8 15 9 10 17 11 12 19 13 21 14 15 23 16 17 25 18 19 27 20 29 21 22 31
Time
Probable exposure period

11. Two ways of making epicurves in Excel
The ”square method”
Turn a work sheet in to squares
Fill in each patient as a square
The ”chart method”
Make a table of onset times
Use the chart wizard
Make a histogram (by removing intervals between bars in a bar chart)