Effects of changes in temperature on Zika dynamics and control

Abstract

When a rare pathogen emerges to cause a pandemic, it is critical to understand its dynamics and the impact of mitigation measures. We use experimental data to parametrize a temperature-dependent model of Zika virus (ZIKV) transmission dynamics and analyse the effects of temperature variability and control-related parameters on the basic reproduction number ( R 0 ) and the final epidemic size of ZIKV. Sensitivity analyses show that these two metrics are largely driven by different parameters, with the exception of temperature, which is the dominant driver of epidemic dynamics in the models. Our R 0 estimate has a single optimum temperature (≈30°C), comparable to other published results (≈29°C). However, the final epidemic size is maximized across a wider temperature range, from 24 to 36°C. The models indicate that ZIKV is highly sensitive to seasonal temperature variation. For example, although the model predicts that ZIKV transmission cannot occur at a constant temperature below 23°C (≈ average annual temperature of Rio de Janeiro, Brazil), the model predicts substantial epidemics for areas with a mean temperature of 20°C if there is seasonal variation of 10°C (≈ average annual temperature of Tampa, Florida). This suggests that the geographical range of ZIKV is wider than indicated from static R 0 models, underscoring the importance of climate dynamics and variation in the context of broader climate change on emerging infectious diseases.

Humidity – The overlooked variable in the thermal biology of mosquito‐borne disease

“…These studies have, again, focused largely on the effects of ambient temperature. However, seasonal and regional variation in humidity and precipitation could extend or shorten the transmission season and magnify or depress the intensity of epidemics as predicted from models incorporating the effects of temperature alone (Huber et al, 2018; Ngonghala et al, 2021). For example, this is likely to be the case in seasonally dry environments where mosquito‐borne disease transmission tends to be highest during or just after the rainy season and lowest during the hottest / driest parts of the season due to seasonal shifts in mosquito habitat, as well as the effects of temperature and humidity on mosquito and pathogen traits relevant for transmission.…”

“…Arthropod vectors experience a complex suite of environmental factors, both abiotic (e.g., temperature, rainfall, humidity, salinity) and biotic (e.g., biological enemies, inter-and intraspecific interactions and variation in habitat quality). These factors vary in their relative effects on organismal fitness, can synergize (Huxley et al, 2021(Huxley et al, , 2022Kleynhans & Terblanche, 2011;Liu & Gaines, 2022), and exert their effects at different spatial scales (Cohen et al, 2016) with important consequences for the abundance and distribution of arthropod vectors (Evans et al, 2019;Ryan et al, 2015), vector population dynamics (Murdock et al, 2017) and pathogen transmission (Huber et al, 2018;Mordecai et al, 2013;Mordecai et al, 2017;Murdock et al, 2016;Murdock, Blanford, Hughes, et al, 2014a;Ngonghala et al, 2021;Samuel et al, 2011;Shocket, Vergara, et al, 2018b;Tesla et al, 2018;Wimberly et al, 2020).…”

Humidity - The Overlooked Variable in Thermal Biology of Mosquito-Borne Disease

“…Several key biological insights have resulted from this general approach. First, temperate areas of the world that currently experience relatively cool temperatures are expected to increase in thermal suitability for many mosquito-borne diseases with future climate warming (Siraj et al 2014;Ryan et al2015;Tesla et al 2018;Ryan et al 2020a), and, in temperate regions, mosquito-borne pathogens can invade or spread during the summer in seasonally varying environments (Huber et al 2018;Ngonghala et al 2021). Secondly, areas that are currently permissive (near the T opt ) or warmer than the T opt for transmission are expected to experience a decline in thermal suitability with future warming (Ryan et al2015(Ryan et al , 2020bMurdock et al 2016).…”

“…These studies have, again, focused largely on the effects of ambient temperature. However, seasonal and regional variation in humidity and precipitation could extend or shorten the transmission season and magnify or depress the intensity of epidemics as predicted from models incorporating the effects of temperature alone (Huber et al2018;Ngonghala et al 2021). For example, this is likely to be the case in seasonally dry environments where mosquito-borne disease transmission tends to be highest during or just after the rainy season and lowest during the hottest / driest parts of the season due to seasonal shifts in mosquito habitat, as well as the effects of temperature and humidity on mosquito and pathogen traits relevant for transmission.…”

“…Arthropod vectors experience a complex suite of environmental factors, both abiotic (e.g., temperature, rainfall, humidity, salinity) and biotic (e.g., biological enemies, inter-and intra-specific interactions, and variation in habitat quality). These factors vary in their relative effects on organismal fitness, can synergize (Kleynhans & Terblanche 2011;Huxley et al 2021Huxley et al , 2022Liu & Gaines 2022), and exert their effects at different spatial scales (Cohen et al 2016) with important consequences for the abundance and distribution of arthropod vectors (Ryan et al 2015;Evans et al 2019), vector population dynamics (Murdock et al 2017), and pathogen transmission (Samuelet al 2011;Mordecai et al 2013;Murdock et al2014aMurdock et al , 2016Mordecai et al 2017;Huber et al 2018;Shocket et al 2018b;Tesla et al 2018;Wimberly et al 2020;Ngonghala et al 2021).…”