Risk factors for brucellosis seroprevalence of sheep and goat flocks in Spain.

Risk factors for ovine and caprine brucellosis in the Avila region (center of Spain) were evaluated using data from a cross-sectional study of the most important diseases of small ruminants in this Spanish region between 1996 and 1997. Questionnaire data from 56 herds (35 ovine and 21 caprine) were used. Sixteen (29%) flocks (3 caprine and 13 ovine) were brucellosis-seropositive. Overall, 0.7% of sheep and 0.1% of goats were seropositive. Eleven risk factors were studied at the group level by logistic regression using flock brucellosis-status as outcome, and by linear regression using percentage of brucellosis-seropositivity as outcome. Both final models contained the same variables: contact with sheep and grazing in communal pastures as risk factors, and frequency of disinfecting practices as a protective factor.

Soil type as a putative risk factor of ovine and caprine paratuberculosis seropositivity in Spain.

Relationships between soil type and ovine and caprine paratuberculosis in the Avila region (central Spain) were evaluated using data from a cross-sectional study of the most-important diseases of small ruminants in this Spanish region between 1996 and 1997. Questionnaire data from 61 herds (38 ovine and 23 caprine) and 1451 serum samples (1041 ovine and 410 caprine) were used. Herd paratuberculosis (herds were scored as positive to paratuberculosis if any of the serum samples was positive in an agar-gel immunodifussion) was the outcome of interest, whereas soil type in the municipality where farms were located was the predictor variable. Other variables related to soil and soil usage, and herd size, replacement, main food production and animal species were also introduced into the multivariable logistic regression. The final model contained only two independent variables: the predictor variable soil type (coded as two dummy variables ST-1 and ST-2) and herd size (dichotomized at the highest quartile). The estimated Odds Ratios were 25.9 (95% CI: 1.6, 411) for ST-1 (entisols as soil type) and 3.5 (95% CI: 0.3, 45) for ST-2 (inceptisols as soil type).

Electrochemical determination of the stability of complexes formed by proton-ionizable ligands of 3,5-disubstituted 1H-pyrazole with phenethylamine.

The application of two extreme models for diffusion in two-component systems to electrochemically determine equilibrium constants is discussed. The application of cyclic voltammetric, diferential pulse and rotating-disc electrode voltammetric data to elucidate the stoichiometry and formation constant of complex species by applying a generalization of the molar-ratio method is described. Molar-ratio experiments permit the distinction between the limiting diffusive regimes. The values of the equilibrium stability constants for complexation of phenethylamine and phenethylammonium ions by a 26-membered dioxotetraester crown of 3,5-disubstituted 1H-pyrazole as free ligand 1[L] and as dipyrazolate anion 1'[L(2-)]2Na(+), respectively, were determined.