Background: This a prospective study of the incidence, etiology and epidemiological profile of human brucellosis in the regions of Pallars Jussà y Sobirà (Lleida) for the 1995-1998 period.
Methods: Fifty-five patients diagnosed as having brucellosis were studied. Information was recorded regarding the gender, age, town where residing, occupational hazard, contact with animals and intake of unsterilized dairy products, blood samples having been taken for blood cultures.
Results: A total of ten cases were reported in 1995, fourteen in 1996, fifteen in 1997 and sixteen in 1998, the average cumulative rates being 52 in Pallars Jussà and 129 in Pallars Sobirà. Four times more cases were reported among males (81.8%) than among females (18.2%) (RR: 4.4; CI95% 2.2-8.7). The largest number of cases occurred in March-April, and the fewest during the summer months. Seventy-one percent (71%) of these patients were working at an occupation involving this risk, the direct contagion mechanism being clearly prevalent (71%). The animal species most frequently considered to be the source of infection was that of sheep (65%), followed by cows (47%) and goats (25%). In Pallars Jussà, mainly sheep (RO: 0.3 CI95% 0.1-0.9) and in Pallars Sobirà, cows (RO: 6.6; CI95% 1.8-26.2). Twenty-seven strains of Brucella sp, all of the melitensis species, were isolated.
Conclusions: The number of cases of brucellosis in the regions studied have risen in the 1995-1998 period. The results of study of this are indicative of the characteristic profile of an occupational disease. The etiological agent was Brucella melitensis, biovariety 1 clearly being the most prevalent.