Exposure of US Travelers to Rabid Zebra, Kenya, 2011

kanamycin, or amikacin) (4); no remarkable change in duration of treatment resulted when those 4 cases were removed from analysis. The surveillance system captures only the initial treatment regimen; thus, we could not assess changes to treatment regimens in response to drug susceptibility test results or treatment nonadherence. We observed no difference in history of prior TB; HIV infection; or miliary, meningeal, pediatric, or bone and joint TB among case-patients with isoniazid-resistant versus drug-susceptible TB (p>0.12 for all comparisons). TB treatment recommendations in the United States emphasize completion within 12 months of initiating therapy, with exceptions for rifampin-resistant TB, meningeal TB, and disseminated disease in pediatric patients (children <15 years of age) (1,5). We found no change in treatment duration by drugresistance pattern after removing cases of meningeal TB or cases in children from analysis. The length of TB treatment duration in the United States has improved since therapy outcomes were fi rst recorded in the National TB Surveillance System in 1993. In our study, 90% of case-patients with drugsusceptible TB completed therapy within 373 days, compared with 671 days in 1993 (6), and 90% of patients with isoniazid-monoresistant TB completed therapy within 432 days. Although the percentage of MDR TB cases in the United States has declined since 1993, drug resistance remains a serious concern because the percentage of isoniazid-monoresistant TB cases has remained stable (7). Our analysis suggests that despite the effectiveness of rifampin-containing regimens and an apparent lack of clinical differences to justify extending therapy, longer treatment durations persist among patients with isoniazid-monoresistant TB (8). In our cohort study, <75% of patients with rifampin-monoresistant TB and 40% with MDR TB completed therapy within 24 months, suggesting no improvement since 1993 in the length of treatment duration for rifampin-resistant TB strains (6).