Breteau index as a potential warning tool for dengue outbreaks: a 14-year retrospective analysis in high-risk districts of Punjab-Pakistan

Objective: To evaluate the dengue fever burden across three high-risk districts: Lahore, Sheikhupura, and Rawalpindi, over 14 years (2011–2024), and to assess the predictive validity of the Breteau Index (BI) for forecasting dengue outbreaks.Methods: This retrospective ecological study utilized dengue surveillance data collected from 2011 to 2024 at the Institute of Public Health, Lahore. Laboratory-confirmed dengue cases from Lahore, Sheikhupura, and Rawalpindi were analyzed to determine temporal trends. For BI validation, two Union Councils in Rawalpindi were selected by simple random sampling. The BI was calculated using entomological data from the preceding 10 days at 5-day intervals, with a threshold of >3 considered predictive of dengue transmission. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were calculated using laboratory-confirmed dengue cases as the reference standard.Results: Lahore reported the highest dengue burden, with peak outbreaks in 2011 (16,984 cases) and 2021 (19,942 cases), while Rawalpindi showed a rising trend, reaching 6,606 cases in 2024. Sheikhupura consistently reported fewer cases. A weak negative correlation was observed between dengue cases and vector surveillance activities (r = –0.293). In BI validity assessment, UC Dhoke Munshee showed high sensitivity (100%) and specificity (78.18%), with diagnostic accuracy of 84%, while UC Chak Jalal Din demonstrated high sensitivity (96%) but lower specificity (44.9%) and overall accuracy (62.16%).Conclusion: Lahore remained the principal dengue hotspot, while Rawalpindi showed an increasing disease burden. BI demonstrated high sensitivity and negative predictive value, supporting its usefulness as an early warning tool for dengue surveillance.