Using administrative medical claims data to estimate underreporting and map spatio-temporal clusters of infectious zoonotic diseases in Tennessee

Notifiable diseases require regular and timely reporting of diagnosed cases to aid in prevention and control. However, manual reporting can be burdensome, incomplete and delayed. Managed care organizations (MCO) could play a major role in supporting surveillance efforts and spatio-temporal tracking of infectious zoonotic diseases. The objective is to determined if MCO administrative data is useful in the surveillance of 5 tick-borne (Lyme disease [LD], babesiosis, ehrlichiosis, Rocky Mountain spotted fever [RMSF], tularemia) and 2 mosquito-borne (West Nile virus, La Crosse viral encephalitis) infectious diseases. Disease incidence rates from cases reported to the Tennessee Department of Health (TDH) and medically diagnosed cases captured in MCO claims data were compared using a complete randomized block design within general linear mixed models for the 2000-2009 time period. Spatio-temporal disease clusters were compared using SaTScan™. According to administrative claims data, LD and RMSF incidence was 7.7 times and 1.24 times higher, respectively, than what was actually reported to the state, possibly indicating significant underreporting (P < 0.001). Three (3) cases of babesiosis were discovered using claims data, a significant finding as this disease has never been reported in Tennessee. Significant disease clusters did not overlap between data sources. This study examined data from a single MCO in Tennessee (~50% of the population). Therefore, the level of underreporting could be greater than our current findings. Efforts are underway to combine data from multiple MCOs in Tennessee. We recommend integrating administrative medical claims data with state registry data to improve the current zoonotic surveillance system.