Spatial and temporal analyses of culls due to bovine tuberculosis in slaughterhouses of Minas Gerais state, Brazil, 2008 to 2012

Análise espacial e temporal das condenações por tuberculose bovina em frigoríficos do estado de Minas Gerais, Brasil, 2008 a 2012

ABSTRACT:

The application of spatial and temporal analysis in epidemiology aims to understand the causes and consequences of spatial and temporal heterogeneity in studies of infectious diseases. Bovine tuberculosis (bTB) is a chronic and progressive infectious disease caused by Mycobacterium bovis and is an important zoonosis worldwide. The aim of this study was to conduct spatial and temporal analyses of a secondary database of bTB-positive cases registered by the Federal Inspection Service in two slaughterhouses from the West of Minas mesoregion of Minas Gerais state, Brazil, from 2008 to 2012 and to suggest its use in epidemiological surveillance. The culled cattle with bTB macroscopic lesions during post mortem inspection were considered positive in this study. The data used were the positive cases registered on the “Sistema de Informações Gerenciais do Serviço de Inspeção Federal” (SIG/SIF - Management Information System of the Federal Inspection Service) of the “Ministério da Agricultura, Pecuária e Abastecimento” (MAPA - Ministry of Agriculture, Livestock and Supplies), the number of animals slaughtered monthly and their municipalities of origin, per slaughterhouse. The prevalence (%) of cases per cattle slaughtered was calculated, and the relationship between these cases of bTB and cases of human tuberculosis (hTB) and the GDP per capita of the mesoregions comprising the municipalities surveyed was evaluated. The prevalence was 1,030 cases of bTB (0.28%). The lowest case numbers and prevalence rates were obtained in 2010, while the highest rates were observed in 2011. Slaughterhouse 1 showed stationarity, while Slaughterhouse 2 showed an increasing annual trend for data since October 2009. A statistical correlation between the numbers of cases of bovine and human TB (p=0.006, r=0.148) was observed. The prevalence for Slaughterhouses 1 and 2 were not correlated (p>0.05). The municipalities of origin demonstrated randomness in their spatial distribution. SIG/SIF-MAPA may be used for the analysis of spatial and temporal distribution to contribute to the monitoring of animal health services with information on the prevalence of culling for bTB in the West of Minas, South/Southwest of Minas, Campo das Vertentes and Zona da Mata mesoregions of Minas Gerais, Brazil.

INDEX TERMS:
Spatial analysis; temporal analysis; bovine tuberculosis; monitoring; slaughterhouses; Brazil