Evaluation of the Results and Planning of an Epizootiological Survey Using a Rated Epizooty Index by the Example of the Southern Part of the Caspian Sandy Natural Focus of Plague

The discovery of a plague epizooty in a natural focus is almost a random event. Differentiation of territories within natural plague foci based on the probability of epizooty registration significantly increases the chances of its identifying.
The aim of the work was to calculate the rated epizooty index (EI) using the example of the Caspian sandy natural plague focus (southern part), differentiate the surveyed sectors according to the probability of registering epizootics, and provide proposals for improving the epizootiological survey.
Materials and methods. Data on 335 sectors, primarily spanning 1981–2024, were analyzed. Conventional and rated epizooty indices (CEI and REI) were calculated, the rated one allowing for correcting the detection bias effects.
Results and discussion. Detection bias during focal territory surveys has been confirmed. Compared to conventional EI, the REI has revealed a 1.5-fold increase in low-risk epizooty sectors (low REI values). A mathematically rigorous criterion is proposed to identify low-prospect sectors for epizooty detection (probability threshold: 0.95). This allows reallocating efforts to under-surveyed sectors or those with high REI values. This approach enhances epizootiological monitoring efficiency, optimizes resource allocation, and refines plague focus boundaries.

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