Example: Cumulative Incidence - Denominator - GI Illness
Lead Author(s): Jeff Martin, MD
GI Outbreak
MMWR reported "Pleisomonas shigelloides and Salmonella serotype Hartford Infections Associated with a Contaminated Water Supply - Livingston County, New York, 1996".
"On June 24, 1996, the Livingston County (New York) Department of Health (LCDOH) was notified of a cluster of diarrheal illness following a party on June 22, at which approximately 30 persons had become ill.
- Plesiomonas shigelloides and Salmonella serotype Hartford were identified as the cause of the outbreak.
- 98 attendees were interviewed. 56 (57%) of 98 respondents had illnesses meeting the case definition." This is an example of a CDC outbreak investigation.
Cumulative Incidence
So the cumulative incidence of diarrheal illness in their cohort of 98 following the party was 57% (56/98).
- No time period is explicitly mentioned, but technically this is cumulative incidence over a few days following the party.
- Complete follow-up is possible because the time period is very short.
Denominator
The denominator is the entire study population - 98 individuals.
References
Pleisomonas shigelloides and Salmonella serotype Hartford Infections Associated with a Contaminated Water Supply - Livingston County, New York, 1996. (1998). MMWR, 47 (19), 394 – 396