Role of ProMED-mail in the Early Detection of Dengue Outbreaks in the South Asia Region: A Retrospective Descriptive Study

Background: In South Asia, dengue led to substantial morbidity, mortality, and health system strain. Timely detection of outbreaks is crucial. We evaluated the utility of ProMED-mail in providing early warnings of dengue outbreaks across five South Asian countries. Methods: ProMED-mail reports (January 1, 2024-January 31, 2025) published as outbreak alerts, situation updates, or mortality events were reviewed for Bangladesh, India, Nepal, Pakistan, and Sri Lanka. National dengue trends from ministries of health and WHO-SEAR were analyzed by epidemiological week/month to identify outbreak onset, using a trend-based definition. Lead time was defined as time between the first ProMED-mail alert to estimated national outbreak start. Sensitivity analysis was performed by adjusting the outbreak start time by ±1 week. The median and interquartile range (IQR) of lead times was calculated to assess variability. Findings: 34/150 ProMED-mail reports were outbreak alerts. Calculated lead times ranged –8.6 weeks (Pakistan) to +5 weeks (Bangladesh and Event 2 Sri Lanka), and median (IQR) lead time 4.15(2-5) weeks. ProMED issued early alerts; Bangladesh (+5 weeks), India (+4 weeks), Nepal (~4.3 weeks), and Sri Lanka’s October case rise (+5 weeks). In Pakistan, ProMED identified the outbreak in the absence of publicly available surveillance data. Sensitivity analysis yielded median (IQR) lead times of 3.15(1-4) weeks and 5.15(3-6) weeks when outbreak onset was adjusted by –1 and +1 week, respectively. Conclusion: ProMED-mail provided meaningful lead time in detecting dengue outbreaks in South Asia, supporting its role as an effective early warning system and may facilitate enhance epidemic preparedness in resource-limited settings.