Extrapulmonary Tuberculosis among Somalis in Minnesota1

Abstract

A the incidence of tuberculosis in the United States has declined each year since 1993, tuberculosis remains an important infectious disease in the United States and worldwide. In Minnesota, the incidence of tuberculosis increased during the 1990s and peaked at 4.9 cases per 100,000 population in 2001. From 2001 through 2005, 81% of tuberculosis cases in Minnesota occurred in foreign-born persons; this finding can largely be attributed to dynamic immigration patterns that have included an influx of persons from areas of the world where tuberculosis is endemic (1). Somalia ranks in the top 15 countries of origin for foreign-born persons with cases of tuberculosis in reported in the United States (2). Minnesota has the largest Somali population in the United States (3). Although Somali persons constitute <1% of Minnesota’s population, they accounted for 30% of tuberculosis cases reported statewide from 1999 through 2003. The unique epidemiologic characteristics of foreign-born tuberculosis patients in Minnesota, and Somali tuberculosis patients in particular, have been described (1,4). The emergence of extrapulmonary disease as an important form of active tuberculosis has been noted in many studies (5–7). Our purpose was to describe the characteristics of extrapulmonary tuberculosis in ethnic Somalis in Minnesota and to assess factors that may contribute to its disproportionately high prevalence in this population. The Study Data were obtained from the Minnesota Department of Health’s tuberculosis database, specifically, surveillance and public health case management data on all cases of tuberculosis reported among ethnic Somalis in Minnesota from January 1, 1993, through December 31, 2003. Cases were defined in accordance with the Centers for Disease Control and Prevention’s surveillance case definition for tuberculosis (8). Of the 407 cases of tuberculosis in ethnic Somalis reported to the Minnesota Department of Health during this 10-year period, 239 (59%) had extrapulmonary involvement, including 198 (49%) with exclusively extrapulmonary disease and 41 (10%) with pulmonary and extrapulmonary tuberculosis. The remaining 168 (41%) patients had pulmonary disease only. In 2003, 214 cases of tuberculosis (4.4 cases per 100,000 population) were reported in Minnesota; 173 (81%) of these patients were foreign-born, and 58 (27%) were from Somalia. Of the 58 Somali patients, 45 (78%) had extrapulmonary disease. According to US Census data, an estimated 11,164 ethnic Somalis were residing in Minnesota in 2000 (9); by June 2004, this population had increased to ≈25,000 (9). Based on these numbers, the approximate annual incidence rate of tuberculosis for Somalis in Minnesota in 2003 was 269 cases per 100,000 population, and the approximate rate of extrapulmonary tuberculosis was 209 cases per 100,000 population. Demographic and clinical characteristics of the 239 Somali patients who had extrapulmonary tuberculosis are summarized in the Table. A total of 179 (75%) patients were tested for HIV within 1 year of the diagnosis of tuberculosis; HIV test results were positive for only 2 (1%). The only characteristics that differed significantly between patients with extrapulmonary tuberculosis and pulmonary tuberculosis were age and length of time in the United States before diagnosis. Patients who had extrapulmonary tuberculosis were generally older (mean 26.8 years) than those with pulmonary tuberculosis (mean 23.7 years) (p = 0.01). Similarly, the length of time between arrival in the United States and diagnosis of tuberculosis was generally longer for patients with extrapulmonary tuberculosis (mean 2.7 years) than for those with pulmonary disease (mean 1.3 years) (p<0.00001). In a logistic regression model that controlled for the confounding effects of length of time in the United States on the association between a patient’s age and risk for extrapulmonary disease, only the patient’s duration of residence in the United States was significantly associated with extrapulDISPATCHES

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@inproceedings{Rock2006ExtrapulmonaryTA, title={Extrapulmonary Tuberculosis among Somalis in Minnesota1}, author={Robert Bryan Rock and Wendy Mills Sutherland and Cristina A. Baker and David Neville Williams}, year={2006} }