Leveraging Sentinel Enhanced Surveillance to Characterize the 2024-2025 Dengue Epidemic in Puerto Rico: Insights and...

Puerto Rico's 2024-2025 dengue epidemic highlighted the need to understand how complementary surveillance systems capture cases and severity. We compared the Sentinel Enhanced Dengue Surveillance System (SEDSS) and the Passive Arboviral Disease Surveillance System (PADSS) in capturing characteristics of dengue cases during this epidemic and assessed their complementary roles in epidemic monitoring and public health preparedness.

We analyzed laboratory-confirmed dengue cases reported in SEDSS and PADSS from January 1, 2024, through January 31, 2025. SEDSS recruits at sentinel sites, collecting clinical, epidemiological, and laboratory data, while PADSS relies on clinician-initiated reporting across the island. We used descriptive statistics, cross-correlation analyses, and generalized additive models to compare temporal trends, demographic characteristics, clinical features, and severe dengue outcomes.

SEDSS enrolled 373 dengue patients (7.0% of tested patients), while PADSS reported 6488 dengue patients (60.1% of tested patients). Both systems showed aligned epidemic peaks, although PADSS detected more cases overall. Compared with PADSS patients, SEDSS patients were younger (median age = 22 vs 27 y) and had higher proportions of warning signs, including mucosal bleeding (21.7% vs 6.9%), hemoconcentration (4.4% vs 0.1%), and restlessness (31.1% vs 7.5%) (P < .001 for all). Severe dengue was more common in SEDSS patients (9.1% vs 5.6%; P = .02), likely due to more detailed clinical data, with the highest rates among patients aged 10 to 19 years (16.3%) and <10 years (10.5%). SEDSS captured severe plasma leakage (6.2%), which was not recorded in PADSS. PADSS provided broader geographic coverage.

SEDSS captures detailed clinical data, whereas PADSS provides broader coverage and higher case counts. Integrating both systems strengthens epidemic response, resource allocation, and public health decision-making.