The region of Tras-os-Montes e Alto Douro in northeast Portugal displayed the highest prevalence of brucellosis in small ruminants of the country. A vaccination programme of the whole population with Brucella melitensis Rev-1 was carried out from 2001 to 2004 in an attempt to reduce prevalence levels and protect public health. Although individual prevalence decreased from 5.6% in 2001 to 0.4% in 2007, several flocks continued to present individual prevalence ≥ 5.0%. Given the multifactorial characteristics of brucellosis, the current study evaluated farming practices and risk factors in flocks with an individual prevalence over 5% by multifactorial correspondence analysis. Results showed that a lack of recognition of the symptoms of brucellosis and lack of Rev-1 vaccination were the main factors contributing to the high individual prevalence of brucellosis in flocks. Other factors such as the consumption of raw milk, presence of dog commingling with animals and use of communal pastures also contributed to the persistence of the disease. Family farms with low economical profit, minimal training/education of farmers, and a scarcity of veterinary support may explain the persistence of factors contributing to the high prevalence of brucellosis. The results of this study highlight several risk factors and farming practices that might have contributed to the maintenance of a high prevalence of brucellosis in flocks with high brucellosis prevalence. These results could be used to adopt new approaches to improve the efficiency of brucellosis eradication programs.
Keywords: Brucellosis; Multifactorial correspondence analysis; Risk factor; Small ruminants; Vaccine Rev-1..