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

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.