Incidence / attack rate

Mozambique: Beira - Cholera cases (as of 2 April 2019)

Incidence proportion or attack rate measured as the number of new cases per population over a given period of time, where the population is measured as an average within the given time period or at a midpoint population. Incidence is used to represent the risk / probability of contracting a specific disease. Incidence can also be measured as a secondary attack rate looking at the number of cases transmitted through contact per contact.

Strategic or operational?

Both

Basemap, baseline or situational?

Baseline and Situational

When might it be produced?

Prevalence maps are used to understand the risk / probability of contracting a specific disease. These maps should be created as soon as the information is available and continually updated through an emergency, it is particularly important to look at these maps over time to show how a disease is progressing.

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.

Methods

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 an attack rate or a secondary attack rate? What population was used as the denominator? Is the rate per 1,000, 10,000 or 100,000 population?

Incidence is calculated as the volume of anew cases with a specific disease divided by the population at risk, if population data is not available it may also be shown as a volume of new cases with a specific disease 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 new cases over a given time period

• Count of new cases over a given time period divided by population at risk at the beginning of the

  time period - 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