Fig. 4

Efficacy of three eradication strategies applied in Spain. Until 1998, standard B. abortus S19 vaccination was applied in 3–6 months old calves throughout Spain, with variable intensity depending upon the region. Then, S19 vaccination was banned in all regions except Aragón, where coverage had been poor. After 1998 the strategies varied depending upon the regions. A T/S and no vaccination (European Union Directives 77/391/CEE and 78/52/CEE). Most regions attained eradication in 2012 and remained essentially free. The few outbreaks were cleaned by slaughtering the affected herds. B T/S and vaccination with RB51. Cantabria, Castilla-León, and Extremadura started the same T/S program as regions in A but herd prevalence increased progressively. In 2002, Cantabria started mass vaccination with full doses of RB51 plus revaccination 6 months later, irrespective of the age and reproductive condition, combined with TS (but see Safety section in the text), a strategey that became official also in Castilla-León and Extremadura in 2004. Altogether, 721,683 cows were vaccinated/revaccinated from 2002 to 2011 (no official data are available after 2011). Although prevalence decreased significantly, eradication was not achieved until 2018 (Castilla-León and Cantabria) or 2019 (Extremadura). C T/S and conjunctival vaccination with S19. Owing to the very high herd prevalence (over 16% in 1998, with about one third of herds infected by B. melitensis), Aragón implemented a compulsory S19 conjunctival vaccination program (5 × 10.⁹ CFU, either as one or two doses 2–3 months apart, or only a dose after year 2000) of 3–6 months old calves, combined with the European Union compulsory T/Sprogram. A total of 38,754 replacement calves were vaccinated from 2002 (no previous data are available) to 2010. Eradication was achieved in 2010, somewhat earlier than in the regions applying just T/S, and significantly faster than in those using RB51. Data from [138, 139]