| risk factors for brucellosis seropositivity of goat herds in the mexicali valley of baja california, mexico. | a case-control study was conducted in the mexicali valley to identify risk factors for goat-herd seropositivity for brucella melitensis. nineteen case herds (> or = 2 positive results with the 8% rose bengal plate test (rbt)) and 55 control herds (zero positive results in rbt), matched for herdsize and geographic location, were enrolled. conditional logistic regression was used to construct a multivariable model of the odds of seropositivity using variables assessed in a questionnaire administer ... | 1998 | 9879591 |