The famous upward climb of dengue fever into the mountains of Nepal might just be a mistake in how the data was calculated.
April 25, 2026
Original Paper
Population-weighted elevation reveals that coarse district-level analyses overestimate the altitudinal shift of dengue in Nepal
SSRN · 6642098
The Takeaway
Many climate change studies suggest that mosquitoes and diseases like dengue are moving to higher altitudes as the planet warms. This research shows that these conclusions were often based on the average elevation of entire districts rather than where people actually live. When the data is adjusted to account for population centers, the perceived shift in altitude mostly disappears. This means the disease isn't necessarily climbing higher, it is just spreading through the people in already inhabited areas. This finding forces health officials to rethink how they track and predict the spread of tropical diseases in mountainous regions. Statistical artifacts can create a false map of climate migration.
From the abstract
The potential altitudinal expansion of dengue fever under climate change has received increasing attention. In Nepal, rising dengue incidence across all districts has been interpreted as evidence of spread into higher elevations. However, such conclusions are often based on district-level aggregated data, which can misrepresent transmission patterns in a highly heterogeneous mountainous landscape. District mean elevation frequently includes extensive uninhabited high-altitude areas, leading to o