Background
A third of the world population is infected with tuberculosis (TB) bacilli. TB accounts for 25 % of all avoidable deaths in developing countries. The objective of the study was to assess impact of directly observed treatment short-course (DOTS) strategy on new tuberculosis case finding and treatment outcomes in Somali Regional State, Ethiopia from 2003 up to 2012 and from 2004 up to 2013, respectively.

Methods
A health facility based retrospective study was employed. Quarterly reports were collected using World Health Organization (WHO) reporting format for TB case finding and treatment outcome from all zones in the region to the Federal Ministry of Health.

Results
A total of 31, 198 all types of new TB cases were registered and reported during the period from 2003 up to 2012, in the region. Out of these, smear positive pulmonary TB cases were 12,466 (40 %), and 10,537 (33.8 %) and 8195 (26.2 %) for smear negative pulmonary TB and extra-pulmonary TB cases, respectively. An average case detection rate (CDR) of 19.1 % (SD 3.6) and treatment success rate (TSR) of 85.5 % (SD 5.0) for smear positive pulmonary TB were reported for the specified years period. For the overall study period, trend chi-squire analysis for CDR was X 2 = 2.1; P > 0.05 and X 2 = 5.64; P < 0.05 for TSR.

Conclusions
The recommended TSR set by WHO was achieved (85.5 %) and the CDR reported was far below (19.1 %) from the recommended target. Extensive efforts should be established to maintain the achieved TSR and to increase the low CDR for the smear positive pulmonary TB cases through implementing alternative case finding strategies.