1
Sporadic disease pattern Cases occur infrequently and without any obvious pattern e . g . Epizootic ulcerative syndrome ( EUS ) in Murray cod ( Figure 3 ).
30
2
3
4
5
6
Number of new aquatic cases
25
20
15
10
5 0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Months Figure 3 . Epidemic curve of a sporadic disease
Outbreak / Epidemic 2 Cases occurring in clear excess of what would be expected for the population ( Figure 4 ). If there were a number of farms infected with the disease clustered in time and space we would more likely consider this an epidemic .
30
7
8
9
10
Number of new aquatic cases
25
20
15
10
5 0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Days Figure 4 . Epidemic curve of an outbreak / epidemic
2 The term outbreak is often used interchangeably with epidemic .
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