VHA administrative inpatient and outpatient datasets were queried separately for monthly occurrence of dengue and dengue-like diagnosis codes (ICD-9-CM 061, 065.4, 066.3 and V73.5) in PR for Federal Fiscal Year (FY) 1997 to FY 2011 (up to August). Patients are unique within each FY and are counted at the first occurrence of the noted code(s). Wavelet time series analysis using the Morlet wavelet was performed to identify the presence and scale of periodic components in the inpatient and outpatient time series. Wavelet coherence analysis was subsequently carried out to determine the statistical association R(a,t) between the two time series at multiple periodic scales 'a' and time scales 't' (see equation).