A 24-year study of the epidemiology of human brucellosis in a health-care system in Eastern Saudi Arabia

Abstract

Objective: The aim of the study was to examine the epidemiology of human brucellosis in a helath-care system in Eastern Saudi Arabia.

Methods: All cases of human brucellosis from 1983 to 2007 were analyzed.

Results: In the study period, there were 913 patients with brucellosis in the Saudi Aramco health-care system. There were 608 males and 305 females with a male to female ratio of (2:1). The annual incidence rate per 100,000 populations increased from 13 to 70 in 1983 and 1987, respectively, then decreased to 9 in 2006. The age of the patients ranged from 1 to 83 years with a mean age of 35.8+/-17.9 years and a median of 36 years. Of the total patients, 195 (21%) and 155 (17%) cases occurred in those between 20-30 and 31-40 years of age, respectively. Children (< or =10 years of age) constituted 5% of all the patients. The adjusted rate per 100,000 population showed that the highest rate was in those 40-49 years of age (100/100,000) and the lowest rate was in patients less than 10 years of age (2.9/100,000). The number of cases was highest in April to June (n=361; 39.5%) and the lowest reported cases were in January. Of the 219 patients whom their families had animals, 125 (57.1%) had camels, 49 (22.4%) had sheep, 24 (11%) had goats, and 21 (9.6%) had cows. Blood cultures were positive in 80.7% (201/247) of cases. There was no association between age group and the rate of positive blood culture (P value=0.244). The titer of brucella serology was 1:320 in 34.3%, 1:640 in 31%, 1:1280 in 24.7%, > or =1:2560 in 10%. The higher brucella titers were associated with higher rate of positive cultures (P value=0.0002).

Conclusion: There was a decrease in the incidence of brucellosis over the study period. The highest incidence was in patients 40-49 years of age. Continued surveillance and efforts are needed to further decrease the cases of brucellosis.