Temperature explains broad patterns of Ross River virus transmission.

Marta Strecker Shocket,Erin A Mordecai,Sadie J Ryan

doi:10.7554/elife.37762

Marta Strecker Shocket, Erin A Mordecai + Show 1 more

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https://doi.org/10.7554/elife.37762

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Abstract

Thermal biology predicts that vector-borne disease transmission peaks at intermediate temperatures and declines at high and low temperatures. However, thermal optima and limits remain unknown for most vector-borne pathogens. We built a mechanistic model for the thermal response of Ross River virus, an important mosquito-borne pathogen in Australia, Pacific Islands, and potentially at risk of emerging worldwide. Transmission peaks at moderate temperatures (26.4°C) and declines to zero at thermal limits (17.0 and 31.5°C). The model accurately predicts that transmission is year-round endemic in the tropics but seasonal in temperate areas, resulting in the nationwide seasonal peak in human cases. Climate warming will likely increase transmission in temperate areas (where most Australians live) but decrease transmission in tropical areas where mean temperatures are already near the thermal optimum. These results illustrate the importance of nonlinear models for inferring the role of temperature in disease dynamics and predicting responses to climate change.

Highlights

Temperature impacts the transmission of mosquito-borne diseases via effects on the physiology of mosquitoes and pathogens
As the climate changes, filling these gaps becomes increasingly important for predicting geographic, seasonal, and interannual variation in transmission of mosquito-borne pathogens. We address these gaps by building a model for temperature-dependent transmission of Ross River virus (RRV), the most important mosquito-borne disease in Australia (1500–9500 human cases per year) (Koolhof et al, 2017), and potentially at risk of emerging worldwide (Flies et al, 2018)
We used mosquito life history traits measured in Cx. annulirostris: fecundity, egg survival, the proportion surviving from larvae-to-adulthood, mosquito development rate (MDR), adult mosquito lifespan, and biting rate (a)

Summary

Introduction

Temperature impacts the transmission of mosquito-borne diseases via effects on the physiology of mosquitoes and pathogens. Transmission requires that mosquitoes be abundant, bite a host and ingest an infectious bloodmeal, survive long enough for pathogen development and within-host migration (the extrinsic incubation period), and bite additional hosts—all processes that depend on temperature (Mordecai et al, 2013, Mordecai et al, 2017) Both mechanistic (Mordecai et al, 2013, Mordecai et al, 2017; Liu-Helmersson et al, 2014; Wesolowski et al, 2015; Paull et al, 2017) and statistical models (Perkins et al, 2015; Siraj et al, 2015; Paull et al, 2017; Pena-Garcıa et al, 2017) support the impact of temperature on mosquito-borne disease, important knowledge gaps remain.

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