Abstract

Background:
Bovine tuberculosis (bTB), caused by Mycobacterium bovis, remains an important livestock disease with implications for both animal health and public health. Although Mexico has maintained a national surveillance program for decades, the geographic distribution of BTB indicators has not been examined comprehensively at the national scale.

Aim:
To characterize the geographical distribution and temporal dynamics of official bovine tuberculosis surveillance indicators in Mexico between 2019 and 2024, with focus on regions that repeatedly exhibited elevated standardized rates of tuberculin-reactive cattle.

Methods:
We used official SENASICA reports from the National Campaign Against Bovine Tuberculosis to conduct a retrospective analysis. The datasets included information on intradermal tuberculin testing, slaughterhouse surveillance, and granuloma samples submitted for diagnosis. Rates of tuberculin reactive cattle were standardized per 10,000 animals and were estimated using the 2022 Agricultural Census as the population reference. Geographic distribution and temporal variation of these indicators were described using QGIS.

Results:
From 2019 and 2024 a total of 46.9 million tuberculin tests were performed, identifying 489,501 reactive cattle, and a median national reactivity of 1.04%. High standardized rates were consistently observed in northern and north-central regions, especially Chihuahua, Coahuila, Durango, Nuevo León, Tamaulipas, and the Comarca Lagunera, while several southeastern states showed transient increases. Differences between regions were also found in slaughterhouse inspection coverage, granuloma submissions, and laboratory diagnostic activity, with advanced diagnostic testing concentrated in few laboratories.

Conclusion:
This study identified persistent geographic concentrations of elevated bovine tuberculosis surveillance indicators together with pronounced regional heterogeneity across Mexico. The recurrence of elevated standardized rates in the same production regions over multiple years supports the hypothesis that stable spatial clusters may exist, particularly in northern and north-central Mexico. Future investigations integrating animal-level epidemiological information, herd characteristics, cattle movement data, and formal spatial statistical analyses are needed to evaluate this hypothesis and to clarify the factors underlying these recurrent geographic patterns.

Key words: Bovine tuberculosis; Geographic distribution; Mexico; Surveillance indicators.