2.5 Data collection and organization

2.5.1 Data collection

Several types of data will need to be collected:

Current cholera data
– When suspect cases first began to arrive;
– Daily number of cases and deaths (children < 5 years and children ≥ 5 years and adults) up to the time of the visit.
If available, collect the number of cases by patient origin (e.g. neighborhood, city, district, and region) for case mapping.
This information can be found in a general activity register or a cholera-specific register.
If a cholera-specific register is already in place, ensure that it is up-to-date and all the required data are being recorded (Appendix 3).

Historical cholera data
For each previous outbreak in the area:
– Total number of cases and deaths;
– Date of onset and the duration.
These historical data are useful at this initial stage to estimate the potential size, severity and duration of the current outbreak. They can also indicate whether specific neighbourhoods and cities/villages tend to be affected with every outbreak. These data can usually be found with the local health authorities or at the central level.

Demographic data
Demographic data of the affected and at-risk population (number of people in the neighborhood, city or village) as well as from larger administrative areas (e.g. district and region) in the likelihood that cholera will extend to other populations in the vicinity.

2.5.2 Data organization

(by person, time and place)

By person (individual characteristics)
The number of cases and deaths per age group (< 5 years and ≥ 5 years) for each health facility are the only essential data needed at this stage. With these figures, the overall case fatality rate (CFR) can be calculated.

By time
The number of cases and deaths is reported each day. Draw an epidemic curve (bar graph) plotting the number of cases and the CFR per day up to the time of the investigation, then throughout the epidemic (Section 2.7.1).
If there is more than one local health facility reporting cases within the administrative area being investigated (city, district, region, etc.), a single graph combining the data from all these facilities will suffice for initial reporting purposes.

By place
If information on patient origin is available, the total number of patients coming from each distinct location should be used for case mapping (Section 2.7.1).