Prevalence and space distribution of brucellosis, bovine leukaemia, bovine viral diarrhea and infectious bovine rhinotracheitis by using bulk milk ELISA test in dairy herds of the IX Region, Chile

Abstract

Chile is internationally recognized for its good zoo-sanitarian situation as the country has been able to reach and maintain a status of officially free from the main diseases of the OIE List, including foot and mouth disease and classical swine fever. However, several infectious diseases are known to remain among herds, which produce a major effect in production due to losses by abortion, decrease of fertility and what it is more important, some of them represent barriers for export and constitute a risk of zoonosis for the population. In this work, a monitoring system based on the analysis of bulk milk antibodies by means of ELISA test, was implemented to study the epidemiology and distribution of 4 of the main bovine diseases that currently affect the IX Region of Chile (brucellosis, bovine leukaemia, IBR and BVD). The system allowed the surveillance of 279 dairies, which represented 43% of the dairies registered in IX the Region, and included 19,635 milking cows (14%). With this system, a high prevalence for leukaemia (59%), IBR (76%) and BVD (96%) could be established, whereas it was confirmed that brucellosis is restricted to a few dairies (5%). The surveillance system coupled to the satellite geographic information analysis, allowed to establish the space distribution of these diseases in the different communes of the Region, demonstrating to be an excellent and low cost support tool for the monitoring of the diseases in the herd, which guarantees the possibility of establishing this platform in the Region and its feasibility to project it at national level.