Risk factors for brucellosis--Leylek and Kadamjay districts, Batken Oblast, Kyrgyzstan, January-November, 2003

Abstract

Introduction: Brucellosis is a zoonotic disease that is associated with chronic serious sequelae in humans. During 1997-2002, the reported incidence of human brucellosis in Kyrgyzstan increased nearly twofold, from 20 to 36 per 100,000 population. In 2002, the highest incidence of brucellosis was reported in two rural districts of Batkan Oblast: Leylek (106 per 100,000 population) and Kadamjay (80 per 100,000 population). During January-November 2003, trainees from the Applied Epidemiology Training program in Central Asia conducted a matched, hospital-based, case-control study to identify risk factors for brucellosis and describe the epidemiology of disease in these two districts.

Methods: Brucellosis cases were defined on the basis of epidemiologic, clinical, and laboratory criteria. During January-November 2003, a total of 100 persons with confirmed brucellosis were identified in the infectious disease wards of the two district hospitals; these persons were matched by age and date of admission to 100 controls who were admitted to other hospital wards for unrelated conditions. Data on socioeconomic and occupational factors and history of exposure to animals and animal products were collected by using a structured questionnaire. Conditional logistic regression was used to study the association between exposure variables and brucellosis.

Results: Among the 100 persons with confirmed brucellosis during the study period, 86 (86%) owned farm animals, and 45 (45%) became ill during April-May, the birthing season for farm animals. Multivariate analysis indicated that brucellosis was associated with exposure to aborted farm animals in the household (odds ratio [OR] = 29.8; 95% confidence interval [CI] = 4.4-203.4) and consumption of home-made milk products obtained from bazaars or neighbors (OR = 11.4; CI = 1.6-83.9). Knowledge of the mode of brucellosis transmission appeared to be protective against disease transmission (OR = 0.2; CI = 0.03-0.8).

Discussion: Exposure to aborted home-owned animals and consumption of home-made milk products obtained from bazaars or neighbors were identified as probable sources of human brucellosis infections in the study districts. This finding suggests that brucellosis spreads among farm animals in the area and that home-made milk products are not adequately pasteurized.

Conclusion: To reduce the burden of brucellosis in Batken Oblast, veterinary services should be improved, and health education programs should be increased. Implementing these measures should minimize exposure to farm animals and reduce the risk for infection from locally produced milk products.