Temperature impacts the environmental suitability for malaria transmission by <i>Anopheles gambiae</i> and <i>Anopheles stephensi</i>

Villena, Oswaldo C.; Ryan, Sadie J.; Murdock, Courtney C.; Johnson, Leah R.

doi:10.1002/ecy.3685

Cited by 59 publications

(84 citation statements)

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“…The influence of temperature on these traits is typically nonlinear and unimodal with clear optima [52] and subject to interactions with other factors such as the demographic structure of the mosquito population [53]. This has significant consequences for mosquito population dynamics and, in turn, the range and dynamics of vector-borne diseases (such as malaria) they underpin [54–56]. Our results therefore suggest a role for both rainfall and temperature in shaping annual patterns of mosquito abundance and underscores the importance of considering seasonal fluctuations in a range of environmental variables when trying to understand seasonality in mosquito population dynamics.…”

Section: Discussionmentioning

confidence: 99%

A novel statistical framework for exploring the population dynamics and seasonality of mosquito populations

et al. 2022

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Understanding the temporal dynamics of mosquito populations underlying vector-borne disease transmission is key to optimizing control strategies. Many questions remain surrounding the drivers of these dynamics and how they vary between species—questions rarely answerable from individual entomological studies (that typically focus on a single location or species). We develop a novel statistical framework enabling identification and classification of time series with similar temporal properties, and use this framework to systematically explore variation in population dynamics and seasonality in anopheline mosquito time series catch data spanning seven species, 40 years and 117 locations across mainland India. Our analyses reveal pronounced variation in dynamics across locations and between species in the extent of seasonality and timing of seasonal peaks. However, we show that these diverse dynamics can be clustered into four ‘dynamical archetypes’, each characterized by distinct temporal properties and associated with a largely unique set of environmental factors. Our results highlight that a range of environmental factors including rainfall, temperature, proximity to static water bodies and patterns of land use (particularly urbanicity) shape the dynamics and seasonality of mosquito populations, and provide a generically applicable framework to better identify and understand patterns of seasonal variation in vectors relevant to public health.

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Section: Discussionmentioning

confidence: 99%

A novel statistical framework for exploring the population dynamics and seasonality of mosquito populations

et al. 2022

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“…We did not consider life span of any specific Anopheles mosquito species as only three Anopheles species from 300 to 2000 m were reported in the western Himalayan region and none implicated for their role in malaria transmission (Devi & Jauhari, 2004 ). Given that thermal tolerance differs by mosquito species when transmitting the same pathogen (Villena et al, 2022 ) and could change spatial extent of suitability of parasite transmission, our parasite development rate could change if mosquito species were considered as the main factor. Nonetheless, malaria incidence has been reported from human dominated hilly areas below 2000 m in western Himalayan region with high prevalence for Anopheles mosquitoes incriminated as prime malaria vectors (Shukla et al, 2007 ).…”

Section: Discussionmentioning

confidence: 99%

“…Until 2010, most mechanistic models of human Plasmodium transmission were based on the degree‐day model of Detinova (Detinova, 1962 ). More recently, multiple mechanistic models explained unimodal or nonlinear relationship between temperature and length of parasite development period (Beck‐Johnson et al, 2013 ; Mordecai et al, 2019 ; Villena et al, 2022 ). The Detinova model assumes a linear relationship between ambient temperature ( T ) and the parasite development rate (PDR).…”

Section: Introductionmentioning

confidence: 99%

“…Beck‐Johnson et al ( 2013 ) modeled temperature‐driven temporal changes in changes in mosquito age structure and population dynamics to predict shift in malaria seasonality and disease risk. Villena et al ( 2022 ) showed that the effect of temperature on parasite transmission could vary by mosquito species—the upper thermal limits varied significantly between the parasite transmission by the same mosquito species ( An. stephensi ) and between mosquitoes carrying P. falciparum .…”

Section: Introductionmentioning

confidence: 99%

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Exploring the thermal limits of malaria transmission in the western Himalaya

Mozaffer

Menon

Ishtiaq

2022

Ecology and Evolution

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Environmental temperature is a key driver of malaria transmission dynamics. Using detailed temperature records from four sites: low elevation (1800), mid elevation (2200 m), and high elevation (2600–3200 m) in the western Himalaya, we model how temperature regulates parasite development rate (the inverse of the extrinsic incubation period, EIP) in the wild. Using a Briére parametrization of the EIP, combined with Bayesian parameter inference, we study the thermal limits of transmission for avian ( Plasmodium relictum ) and human Plasmodium parasites ( P. vivax and P. falciparum ) as well as for two malaria‐like avian parasites, Haemoproteus and Leucocytozoon . We demonstrate that temperature conditions can substantially alter the incubation period of parasites at high elevation sites (2600–3200 m) leading to restricted parasite development or long transmission windows. The thermal limits (optimal temperature) for Plasmodium parasites were 15.62–34.92°C (30.04°C) for P. falciparum , 13.51–34.08°C (29.02°C) for P. vivax , 12.56–34.46°C (29.16°C) for P. relictum and for two malaria‐like parasites, 12.01–29.48°C (25.16°C) for Haemoproteus spp. and 11.92–29.95°C (25.51°C) for Leucocytozoon spp. We then compare estimates of EIP based on measures of mean temperature versus hourly temperatures to show that EIP days vary in cold versus warm environments. We found that human Plasmodium parasites experience a limited transmission window at 2600 m. In contrast, for avian Plasmodium transmission was not possible between September and March at 2600 m. In addition, temperature conditions suitable for both Haemoproteus and Leucocytozoon transmission were obtained from June to August and in April, at 2600 m. Finally, we use temperature projections from a suite of climate models to predict that by 2040, high elevation sites (~2600 m) will have a temperature range conducive for malaria transmission, albeit with a limited transmission window. Our study highlights the importance of accounting for fine‐scale thermal effects in the expansion of the range of the malaria parasite with global climate change.

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“…For this study, the transmission models for thermal suitability for a combination of Anopheles stephensi and Plasmodium falciparum (ASPF) and An. stephensi and Plasmodium vivax (ASPV) from Villena et al [ 29 ] were used. Specifically, temperature dependent mechanistic models were used to assess suitability of malaria transmission by An.…”

Section: Introductionmentioning

confidence: 99%

Malaria transmission in Nepal under climate change: anticipated shifts in extent and season, and comparison with risk definitions for intervention

Bhattarai

Blackburn

Ryan

2022

Malar J

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Background Climate and climate change affect the spatial pattern and seasonality of malaria risk. Season lengths and spatial extents of mapped current and future malaria transmission suitability predictions for Nepal were assessed for a combination of malaria vector and parasites: Anopheles stephensi and Plasmodium falciparum (ASPF) and An. stephensi and Plasmodium vivax (ASPV) and compared with observed estimates of malaria risk in Nepal. Methods Thermal bounds of malaria transmission suitability for baseline (1960–1990) and future climate projections (RCP 4.5 and RCP 8.5 in 2030 and 2050) were extracted from global climate models and mapped for Nepal. Season length and spatial extent of suitability between baseline and future climate scenarios for ASPF and ASPV were compared using the Warren’s I metric. Official 2010 DoHS risk districts (DRDs) and 2021 DoHS risk wards (DRWs), and spatiotemporal incidence trend clusters (ITCs) were overlaid on suitability season length and extent maps to assess agreement, and potential mismatches. Results Shifts in season length and extent of malaria transmission suitability in Nepal are anticipated under both RCP 4.5 and RCP 8.5 scenarios in 2030 and 2050, compared to baseline climate. The changes are broadly consistent across both future climate scenarios for ASPF and ASPV. There will be emergence of suitability and increasing length of season for both ASPF and ASPV and decreasing length of season for ASPV by 2050. The emergence of suitability will occur in low and no-risk DRDs and outside of high and moderate-risk DRWs, season length increase will occur across all DRD categories, and outside of high and moderate-risk DRWs. The high and moderate risk DRWs of 2021 fall into ITCs with decreasing trend. Conclusions The study identified areas of Nepal where malaria transmission suitability will emerge, disappear, increase, and decrease in the future. However, most of these areas are anticipated outside of the government’s current and previously designated high and moderate-risk areas, and thus outside the focus of vector control interventions. Public health officials could use these anticipated changing areas of malaria risk to inform vector control interventions for eliminating malaria from the country, and to prevent malaria resurgence.

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Temperature impacts the environmental suitability for malaria transmission by Anopheles gambiae and Anopheles stephensi

Cited by 59 publications

References 59 publications

A novel statistical framework for exploring the population dynamics and seasonality of mosquito populations

A novel statistical framework for exploring the population dynamics and seasonality of mosquito populations

Exploring the thermal limits of malaria transmission in the western Himalaya

Malaria transmission in Nepal under climate change: anticipated shifts in extent and season, and comparison with risk definitions for intervention

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