Poster presentado en Brucellosis 2011-International Research Conference

22 de septiembre de 2011

Sanz C., Alvarez J., Reyes A., Saez-LLorente JL., Perez-Sancho M., Hermoso J. y Dominguez L.

In low prevalence settings, eradication of bovine brucellosis (BB) can be achieved through combination of test-andslaughter programs and strict biosecurity measures. However, in high incidence areas, vaccination can help to control outbreaks decreasing the incidence at both an individual and herd level. In 2002 an outbreak of BB began in the north part of Extremadura, Spain, an area where most of the herds (>90%) are extensively managed beef herds. Due to the increasing incidence observed in the area, a series of special measures were introduced to control the spread of the disease, including B19 vaccination of replacement heifers (September 2003) and mass RB51 vaccination of the adult cattle (September 2004). Here, we report changes in the epidemiological indicators in the period 2004-2010 in two of the most heavily affected counties. In this area, a total of 328 farms were subjected to RB51 vaccination: a first RB51 vaccination
was performed in September-December 2004 (9521 animals) and then up to 4 revaccinations were performed annually. Overall, 3371 herd tests on 170 farms (164837 individual tests - Rose Bengal Test + Complement Fixation as confirmatory test) were performed in the area in the period under study, disclosing a total of 1950 reactors (448 positive herd-tests) at some point in 123 herds. Most of the positive herd-tests (90.8%) were registered in the first two years of study, in cattle herds before the first or second dose of RB51 (62% and 21% of the positive tests observed, respectively). Intra-herd monthly incidence in infected herds ranged from 0 to 68% (mean=3.98%). However, it decreased as the number of RB51 inoculations increased (mean monthly incidence in infected herds: before vaccination=5.54%; after first RB51 round =3.09%; after second RB51 round=1.53%; after more than two doses of RB51=0.59%); decrease in animal incidence
was more obvious after the first two doses of RB51 vaccine, and remained below 1% for the following years, as also the number of positive herd-tests decreased (reactors were detected in only 0.3% of the tests performed in the last two years). Here, combination of strict biosecurity measures, a strong diagnostic pressure and a vaccination program was able to decrease the prevalence of BB in the mid-term. Vaccination with RB51 allowed a rapid decrease in the susceptible population in a heavily infected environment, contributing to a fast decline in the individual incidence; this, combined with the frequent testing, permitted the control and eventual eradication after 3-5 years

	Servicio de Zoonosis Emergentes, de Baja Prevalencia y Agresivos Biológicos (NED). Centro de Vigilancia Sanitaria Veterinaria (VISAVET). Universidad Complutense (UCM).
	Departamento de Sanidad Animal. Facultad de Veterinaria. Universidad Complutense (UCM).

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