Seasonal variation of culture positive brucellosis at a major teaching hospital.

Brucellosis is one of the main zoonoses in the world. In Saudi Arabia, it was recognized as a major health problem in 1983G and since then many measures have been implemented to control the disease. We conducted a study to determine the yearly incidence and seasonal variation of blood culture positive brucellosis (Brucella cases) diagnosed at King Khalid University Hospital (KKUH) in Riyadh between 1985G and 1991G. The results showed that there was a fivefold decline in the incidence of Brucella cases over the seven years of the study from 8.6 cases/1000 admissions in 1985G to 1.4 cases/1000 admissions in 1991G. The disease showed a prevalence that extended throughout year with the majority of cases occurring during spring, summer and early fall. The possible reasons for the seasonal variation and decreasing incidence of brucellosis noted in this study are discussed.