An in vitro assay measuring the antimicrobial activity of essential oils of Coridothymus capitatus (Spanish origanum), Satureja montana, Thymus mastichina (Spanish Origanum majorana), Thymus zygis (Spanish variety of Thymus vulgaris) and Origanum vulgare has been carried out against poultry origin strains of Escherichia coli, Salmonella enteritidis and Salmonella essen, and pig origin strains of enterotoxigenic E. coli (ETEC), Salmonella choleraesuis and Salmonella typhimurium. Using the broth microdilution method, all the essential oils showed an MIC > or = 2% (v/v) for the two strains of E. coli. The essential oil that showed the highest antimicrobial activity against the four strains of Salmonella was Origanum vulgare (MIC < or = 1% v/v), followed by Thymus zygis (MIC < or =2% v/v). Thymus mastichina inhibited all the microorganisms at the highest concentration, 4% (v/v), while the rest of the essential oils showed highly variable results. By chemotyping, higher inhibitory capacity was observed in the oils with a higher percentage of phenolic components (carvacrol and thymol) in comparison with oils containing the monoterpenic alcohol linalool. The results of this work confirm the antimicrobial activity of some essential oils, as well as their potential application in the treatment and prevention of poultry and pig diseases caused by salmonella.

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Serum samples from 210 wild ruminants collected between 2006 and 2007 in southern Spain were tested for antibodies against bluetongue virus (BTV) by means of a competitive ELISA assay. Eighty-seven of the 210 wild ruminants analysed (41%) showed antibodies against BTV. Statistically significant differences were found in the seroprevalence among species: 66% (65 of 98) for red deer (Cervus elaphus), 50% (ten of 20) for fallow deer (Dama dama), 33% (three of nine) for mouflon (Ovis aries musimon) and 11% (nine of 83) for Spanish ibex (Capra pyrenaica). Overall, the sites where seropositive wild ruminants were found coincide with the areas where BTV had been detected in livestock, but in eastern Sierra Morena, the virus circulated in wild ruminants, although it had not been detected in domestic ruminants in the same areas. Wild ruminants over 1-year of age (sub-adults and adults) had significantly higher seroprevalences than juvenile animals. Statistically significant differences were also observed between BTV seroprevalence and management (free-ranging vs. captivity) with higher prevalence in freeranging animals. The high seroprevalences obtained suggest that BTV is widespread in wild ruminants in southern Spain. This factor could have an important influence on the evolution of the infection in domestic livestock and indicates the need to include wild ruminant species in BTV surveillance or control programs.

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