Bovine brucellosis control and eradication programme in Chile: vaccine use as a tool within the programme.

In 1975 Chile began the bovine brucellosis control programme in the south central area of the country, where the 92% of the bovine population is located. In 1992 the programme was evaluated and the prevalence showed almost no change for the last nine years, Therefore, a comprehensive Brucellosis eradication programme began. Based on the information gathered by a surveillance system on cattle market and dairy herds from 1999 to 2003 the advances in the process are shown. By applying this programme it has been possible to eradicate brucellosis from the XII Region, and in 2003 was declared brucellosis free with vaccination. In Region XI the project is in its final year and during the last semester no reactor animals have been found. The central south regions began their eradication in 1996. This is the area of the country where the largest bovine population is concentrated, and also the highest brucellosis prevalence. Now the situation has been changing and the trend shows fewer reactors in auction markets and milk plants. The effect of the vaccine (Strain 19 at the beginning and Strain RB 51 from 1997) has been important in impeding the infection of negative herds that are in infected areas. It is also used with success in infected herds, applying "whole herd vaccination" to create a quick herd immunity. This has been important since in Chile there is no paid compensation for reactor animals and the infected animals remain for a variable period in the herd before being destroyed.