A stochastic simulation model for brucellosis eradication in goat flocks in an area with high flock prevalence but low animal prevalence

•Our model predicted time to be free from brucellosis after a test and slaughter.•We explored the most important factors for a successful eradication program.•The uncertainties of reproductive physiology and transmission were included.•Testing before introducing new goats was very important for eradication.•Introducing goat from a brucellosis-free flock was very important for eradication.

Since 2009, the Thai national brucellosis eradication programme has been implemented with the strategy of test-and-slaughter and compensation paid for positive brucellosis goats. Nakhon Pathom is a province located in the west of Thailand. Due to a high volume of goat movement, brucellosis in goat is still problematic with a high prevalence of 31% at the flock level and 1–2% at the goat level. The stochastic simulation model was created to predict the success of the programme, as defined by when goats were free from brucellosis (true prevalence = 0). The scenarios regarding the decisions about the routine testing interval of the test-and-slaughter programme, and the testing for brucellosis before introducing new goats into a flock were simulated. The dynamic and uncertainties of reproductive performance, abortion rate, survival rate, transmission per contact, transmission per mating, vertical transmission rate, level of brucellosis prevalence, and age to sale for young and breeding goats were included in the model. The results indicate that testing for brucellosis before introducing new goats from a flock with an unknown brucellosis status and introducing replacement goats from a brucellosis-free flock were very important for the success of the eradication programme. Furthermore, a short testing interval of the test-and-slaughter regime was also able to eradicate brucellosis-positive flocks faster than a long testing interval.