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Cyclosporiasis Outbreak Investigations: Epi Curves — United States, 2013 (Final Update)

Last Updated December 2, 2013 9:00 AM EDT

Epi Curves

The illnesses can be visually described with a graph showing the number of persons who became ill each week. This graph is called an epi curve.

Figure 1. Confirmed Cyclosporiasis Cases, by Groups of States, June—August 2013*

Epi Line Graph for October 28, 2013

* N=631. Outbreak-associated cases are defined as laboratory-confirmed Cyclospora infection in a person with symptom onset (reported or estimated) between June 1 and August 31, 2013, and no known travel outside the United States or Canada in the 14 days prior to symptom onset.

In the graph above, the number of persons who became ill each week is plotted separately for persons who fell ill in Iowa and Nebraska, in Texas, and in all other states combined, for those cases for which onset of illness dates were available.

The cases reported by Iowa and Nebraska peaked in mid-June, and then decreased to low levels. Cases reported from Texas increased more slowly, reaching a peak in late June-early July, before declining moderately. Cases reported in other parts of the country occurred in lower numbers through June and July, without a distinct peak. This suggests that there was more than one outbreak of cyclosporiasis during June–August 2013 in the United States.

Week of
Illness Onset
Number of Cases
in IA and NE
Number of Cases
in TX
Number of Cases
in Other States
Jun 1782
Jun 81039
Jun 151231321
Jun 22612911
Jun 2987227
Jul 6124722
Jul 1324116
Jul 2023313
Jul 270135
Aug 3073
Aug 10023
Aug 17112
Aug 24011

Figure 2. Confirmed Cyclosporiasis Cases by Week of Illness Onset, United States*

*A total of 645 reported cases not know to be international travel associated had onset of illness between April 28 and September 28, 2013. Of these reported cases, 631 were outbreak associated. Outbreak-associated cases are defined as laboratory-confirmed Cyclospora infection in a person with symptom onset (reported or estimated) between June 1 and August 31, 2013, and no known travel outside of the United States or Canada in the 14 days prior to symptom onset. Reported cases of cyclosporiasis in the United States have returned to baseline levels, as shown by the green line; therefore, it is likely that the outbreaks identified during June–August 2013 have ended. The number of reports of persons with illness increased beginning in June and returned to baseline in mid-to-late August.

« Read the full Outbreak Investigation

Week of Illness OnsetNumber of Cases5-Year Weekly Mean
April 28–May 410.6
May 5–May 1101.8
May 12–May 1821.2
May 19–May 2542.8
May 26–Jun 195.2
Jun 2–Jun 8144.6
Jun 9–Jun 15257.6
Jun 16–Jun 221746.8
Jun 23–Jun 29926.2
Jun 30–Jul 61115.6
Jul 7–Jul 13694.8
Jul 14–Jul 20632.2
Jul 21–Jul 27413.8
Jul 28–Aug 3161.4
Aug 4–Aug 10111.4
Aug 11–Aug 1741.6
Aug 18–Aug 2430.8
Aug 25–Aug 3121.8
Sep 1–710.8
Sep 8–1421
Sep 15–2101.4
Sep 22–2811
 

 


Cyclosporiasis Fact Sheet [PDF - 955 KB]
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