Prevalence
Disease prevalence maps highlight the proportion of people within a population that have a specific disease (both existing and emerging cases), prevalence can be measured at a specific point in time (point prevalence) or over a specific time period (period prevalence). Prevalence maps indicate how widespread a disease is.
Strategic or operational?
Both
Basemap, baseline or situational?
Baseline and Situational
When might it be produced?
Prevalence maps are used to understand how widespread a disease is. They can be created at the beginning of an emergency to understand the underlying disease profile of a population pre-emergency as well as during an emergency to understand how widespread a disease has become.
Intended audience
Invariably health is linked to many other vulnerabilities and is impacted by all eleven clusters in the UN system (sectors of the humanitarian system that help to coordinate a humanitarian response), in particular:
Nutrition
Water, Sanitation and Hygiene (WASH)
Logistics - transport / access
The intended audience includes a variety of actors either directly involved in health, or those supporting health needs:
Ministry of Health / Department for Health
National Health Care Providers
Local Government
Civil Society / Community Organisations
Affected communities / population
National and International health related NGOs
National Red Cross / International Federation of Red Cross
World Health Organisation
Emergency Medical Teams /Emergency Medical Teams Coordination Cell
Influence on humanitarian decisions
Will be dependent on if the maps are strategic, operational or both and will vary by intended audience. To be updated based on planned expert interviews.
Access to timely and accurate data is essential for a health response. It is important to get the best available data although it may not always be perfect. Questions should be asked such as:
When was the data collected? What time period does it cover? When will it next be updated? How accurate is the data? Are the figures actual or estimates? Is it point prevalence or period prevalence? What population was used as the denominator? Is the rate per 1,000, 10,000 or 100,000 population?
Prevalence is calculated as the volume of a population with a specific disease divided by the population, if population data is not available it may also be shown as a volume of people that have a specific disease at a point in time or over a given time period.
Robust information management and governance is essential when accessing, storing and visualising health data. The agreed use of the data must be established and recorded from the outset.
A process of data manipulation may be required to ensure individuals, families or villages can not be identified. A number of methods can be used to achieve this including the suppression of small numbers, aggregation of data to a higher level and minimising the use of other data / detail on a map that could make identification easier. These checks must be in place to ensure patient’s right to privacy and dignity are maintained.
Data
Count of cases at a specific point in time
Count of cases over a given time period
Count of cases at a specific point in time divided by population at risk at the same point in time - often shown as rate per 1,000, 10,000 or 100,000 population
Count of cases over a given time period divided by either the average population over the time period or a midpoint population - often shown as rate per 1,000, 10,000 or 100,000 population
Resources
Global Health Cluster
World Health Organisation
Emergency Medical Teams
Health Resource Availability Monitoring System (HeRAMS)
Early Warning, Alert and Response System (EWARS)
The Sphere Handbook - Minimum standards in Health action
Multi-Cluster / Sector Initial Rapid Needs Assessment (MIRA)
The International Federation of Red Cross and Red Crescent Societies
Ministry of Health / Department of Health (country specific)
ACAPS
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