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Risk-based surveillance

"EUFMD - Demonstration of FMD freedom": 2-stage risk-based surveillance with 1 herd-level risk factor, 1 animal-level risk factor and multiple surveillance components

Herd-level risk factor

Animal-level risk factor


Copy the relevant data from a spreadsheet and paste it into the text boxes below, in the specified formats. Click on the link below to download a spreadsheet showing example data in the correct format. Always include one header row with the correct column names.

Download example data

Herd testing data

Include one row per herd sampled per time period, with different columns for the different surveillance components. The rows required and the header names are:

  • TimePeriod: A number indicating the time period during which the testing took place. This can be just the year (e.g. 2012) or the year and month (e.g. 201201). Text values are acceptable but will be sorted alphabetically (e.g. 2012-01 works better than Jan 2012);
  • HerdID: An identification number for each herd. This is for the user's reference only and is not used in the internal calculations;
  • HerdSize: a positive integer indicating the number of animals in the herd during that time period. If the herd size is not known, this may be left blank;
  • HerdRisk: The risk group of the herd. This must be either 1 (high risk) or 0 (low risk);
  • HRProportion: The proportion of herds in the high risk group. This must be a number between 0 and 1; and
  • For each surveillance component, the number of animals tested:
    •   . HRTested_C1: The number of animals in the high risk group tested under surveillance component 1;
    •   . LRTested_C1: The number of animals in the low risk group tested under surveillance component 2; and
    •   . HRTested_C2, LRTested_C2, etc: the corresponding values for the second and further surveillance components.

Data should be set out as shown in the example spreadsheet.

Probability of introduction data

This data should have one row for every time period. The columns and headers are:

  • TimePeriod: The time period, corresponding exactly to the time periods used in the herd data; and;
  • Pintro: The probability of introduction of disease for that time period, expressed as a number between 0 and 1. The value depends on the time period, being larger if an annual time period is used, compared to a monthly time period.

Component sensitivity data

This data provides the combined test system protocol sensitivity for each of the surveillance components. There should be one row per surveillance system component, and two columns:

  • Component: The name of the surveillance component (for your reference only); and;
  • USe: The unit sensitivity of the component. This is the overall probability that an individual infected animal will be identified as positive through that surveillance component. It includes a combination of tests (usually in series) including confirmatory tests in the case of a suspected diagnosis.

This calculator was prepared for a project funded by EuFMD, and is intended to support the analysis of surveillance data to demonstrate freedom from FMD. Nevertheless, it is a generic calculator and can be used for other diseases as well.

This tool calculates the cumulative probability of freedom from disease, based on the analysis of herd-level risk-based surveillance data over time (with varying probabilities of introduction over time). It allows for one dichotomous herd-level risk factor, one dichotomous animal-level risk factor, and up to three surveillance components with different sensitivity:

As detailed herd-level data is required for multiple surveillance components, this tool uses two types of data input:

  • General parameters, entered in the appropriate fields marked above; and
  • Detailed data which can be entered into a spreadsheet in the specified format, and then copied into the text areas above.

Once data is pasted, click the submit button, then view the results of the analysis at the top of the page.