The impact of climate variability on dengue virus case incidence in Sindh, Pakistan: Post-2022 flooding.

Dengue virus is spread primarily by the Aedes aegypti and Ae. albopictus mosquitoes is a self-limiting viral disease primarily present in the tropical and subtropical regions of the world. Temperature and rainfall impact vector development, virus replication, and habitat suitability for Ae. aegypti and Ae. albopictus larvae and pupae. Pakistan, located in Southeast Asia, is one country where DENV is endemic and impacts thousands of lives each year. In recent years, Pakistan has been hardly hit by climate change, with heavy rainfalls and flooding recurring each year, with simultaneous surges of dengue virus across the country. In this paper, we analyze the monthly dengue virus disease data from Sindh Pakistan, from 2020-2025 to understand the impacts of flooding, rainfall, and temperature fluctuations on dengue case incidence in the region. We use parametric generalized linear models and the generalized additive model. Our results indicate that monthly confirmed dengue cases exhibit a strong seasonality, with the great majority of cases concentrated in the post-monsoon months (September-November). A 1-month lag in rainfall was associated with a statistically significant increase in dengue incidence (IRR = 1.008, 95% CI: 1.003-1.012, p = 0.002), corresponding to a 0.8% increase in expected case counts per unit (mm) increase in rainfall one month prior. In contrast, neither lagged temperature term reached statistical significance.