Optimal temperature for malaria transmission is dramatically lower than previously predicted

TLDR

Mosquito vector and parasite ecology shape malaria incidence, seasonality, and range, yet most models assume linear temperature responses, predicting an optimal transmission temperature of 31 °C. The study aims to develop and apply a model with realistic, nonlinear thermal physiology of insects to better understand how current and future temperature regimes affect malaria transmission. The model integrates empirically derived nonlinear thermal responses of mosquito and parasite life‑history traits, reflecting realistic ecological assumptions about insect thermal physiology. Field data contradict earlier models, and the new model predicts an optimal transmission temperature of 25 °C—six degrees lower than prior estimates—and a sharp decline in transmission above 28 °C, findings confirmed by a large African malaria risk dataset.

Abstract

Abstract The ecology of mosquito vectors and malaria parasites affect the incidence, seasonal transmission and geographical range of malaria. Most malaria models to date assume constant or linear responses of mosquito and parasite life‐history traits to temperature, predicting optimal transmission at 31 °C. These models are at odds with field observations of transmission dating back nearly a century. We build a model with more realistic ecological assumptions about the thermal physiology of insects. Our model, which includes empirically derived nonlinear thermal responses, predicts optimal malaria transmission at 25 °C (6 °C lower than previous models). Moreover, the model predicts that transmission decreases dramatically at temperatures > 28 °C, altering predictions about how climate change will affect malaria. A large data set on malaria transmission risk in A frica validates both the 25 °C optimum and the decline above 28 °C. Using these more accurate nonlinear thermal‐response models will aid in understanding the effects of current and future temperature regimes on disease transmission.