The IHS health database is distributed across the United States with most data maintained at 465 local care facilities. Among these 465 facilities, there are over 235 EHR deployments, using similar but separately maintained configurations of the IHS EHR. Data are entered into the EHR system as part of daily clinical care or transcribed from paper for results of clinical referrals or outside tests. We developed a surveillance system that identifies reportable cases, notifies providers and provides data to a dedicated national surveillance database. Cases are found using a locally deployed extension to the local data system that searches for a combination of ICD-9 codes, clinical data and laboratory data, based on Council of State and Territorial Epidemiologists (CSTE) case definitions, on a nightly basis. Reports for situational awareness and response are made locally, regionally and nationally using an a priori established priority ranking of the public health importance of a case or outbreak.