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 extrapulmonary tuberculosis ( p<0.00001 ) . controlling for age , each additional year of residence in the united states was associated with a 30% increase in the risk for extrapulmonary tuberculosis ( odds ratio 1.3 , 95% confidence interval 1.21.5 ) . a total of 250 sites of extrapulmonary disease were identified in the 239 patients , representing 26 distinct anatomic locations of disease ; several patients had disease in multiple sites : lymph nodes ( 50% ) , pleura ( 9% ) , peritoneum ( 8% ) , skin or soft tissue ( 8% ) , central nervous system ( 6% ) , bones or joints ( 4% ) , various organs ( miliary ) ( 4% ) , urogenital tract ( 2% ) , and other sites ( 9% ) . among the 197 ( 82% ) cases of culture - confirmed extrapulmonary tuberculosis , 18% were resistant to > 1 first - line antituberculosis drug ( i.e. , isoniazid , rifampin , pyrazinamide , or ethambutol ) . the prevalence of resistance to specific first - line drugs ranged from 16% for isoniazid to 3% for rifampin and 2% each for pyrazinamide and ethambutol . the prevalence of multidrug - resistant tuberculosis ( mdrtb ) ( i.e. , resistant to at least isoniazid and rifampin ) was 3% . * tst , tuberculin skin test ; inh , isoniazid ; rif , rifampin ; emb , ethambutol ; pza , pyrazinamide ; mdrtb , multidrug - resistant tuberculosis . resistant to at least inh and rif . of the 186 patients who had extrapulmonary tuberculosis and were treated from 1993 through 2002 , 91% successfully completed an adequate course of therapy , 76% within 12 months . of the 186 treated patients , 55% received strict directly observed therapy , and 25% others received a less intensive form of supervised therapy . response to treatment did not differ significantly between patients who received directly observed therapy or some other form of supervision and those who administered therapy themselves . extrapulmonary tuberculosis is more common than pulmonary tuberculosis in somalis in minnesota . among somali patients who have extrapulmonary tuberculosis , 50% have lymphatic disease , most are < 45 years of age , and slightly more are female ; prevalence of hiv infection is low , prevalence of reactive tuberculin skin tests is high , and prevalence of drug - resistant strains is substantial . these findings are similar to those reported for somali immigrants in other countries ( 10 ) . the prevalence of extrapulmonary tuberculosis among all foreign - born tuberculosis patients in the united states is considerably lower than that reported among somalis in minnesota and elsewhere ( 11 ) , which suggests that the unique characteristics of tuberculosis in this population may reflect host factors or differences in geographically endemic strains of m. tuberculosis . in minnesota , somali patients who had extrapulmonary tuberculosis were older and had resided in the united states longer than somali patients who had pulmonary tuberculosis . these differences likely reflect the relative difficulty in diagnosing extrapulmonary disease compared with pulmonary tuberculosis . to minimize the interval between clinical manifestation of disease and diagnosis , clinicians should maintain an increased level of suspicion for extrapulmonary tuberculosis in somali patients . this study demonstrates how immigration can affect the local epidemiology of tuberculosis through importation of disease patterns from another part of the world .
to analyze extrapulmonary tuberculosis in somalis living in minnesota , we reviewed surveillance and public health case management data on tuberculosis cases in ethnic somalis in minnesota from 1993 through 2003 . 
 the presence of these recent immigrants substantially affects the local epidemiology and clinical manifestation of tuberculosis .