Brucellosis outbreak: analysis of risk factors and serologic screening

Israel is one of the Mediterranean countries in which Brucellosis is endemic. As recently there has been a Brucellosis outbreak in a kibbutz, the aim of this study is to identify asymptomatic infected Kibbutz members, and to delineate the manner of infection in this setting. Therefore, all the asymptomatic Kibbutz members were screened by the Rose Bengal test for Brucellosis, while both patients and healthy members were asked to fill in a questionnaire in order to pinpoint the manner of infection, and signs and symptoms of the disease. In addition to the 14 patients with Brucellosis, 2 other Kibbutz members were also found to be infected by the screening tests. Analysis of the data of the questionnaires from 142 healthy and 16 patients disclosed that almost all of the infected patients (15/16) worked in the cowshed, as opposed to only 24 out of 142 (16.9%) of the healthy members. The infected tended to participate more in calf deliveries, and had contact with cow's blood and placenta, compared with the healthy subjects (P<0.001), while there were no significant differences with respect to having cuts on hands, or working in the cowshed without gloves. In addition, 15 out of 16 (93.8%) infected persons also drank unpasteurized milk, as compared with only 17 of the 142 (12%) healthy members (P<0.001), and thus were exposed to 2 major risk factors (working in the cowshed and consumption of unpasteurized milk). As the cows of the Kibbutz's cowshed were affected by Brucella melitensis (which usually affects flocks of goats and sheep rather than cows), the microbe was probably transmitted to the cowshed from neighboring flocks by wandering dogs, and then to the infected humans.