Quantifying the effects of temperature on mosquito and parasite traits that determine the transmission potential of human malaria
- PMID: 29036170
- PMCID: PMC5658182
- DOI: 10.1371/journal.pbio.2003489
Quantifying the effects of temperature on mosquito and parasite traits that determine the transmission potential of human malaria
- PMID: 29036170
- PMCID: PMC5658182
- DOI: 10.1371/journal.pbio.2003489
Abstract
Malaria transmission is known to be strongly impacted by temperature. The current understanding of how temperature affects mosquito and parasite life history traits derives from a limited number of empirical studies. These studies, some dating back to the early part of last century, are often poorly controlled, have limited replication, explore a narrow range of temperatures, and use a mixture of parasite and mosquito species. Here, we use a single pairing of the Asian mosquito vector, An. stephensi and the human malaria parasite, P. falciparum to conduct a comprehensive evaluation of the thermal performance curves of a range of mosquito and parasite traits relevant to transmission. We show that biting rate, adult mortality rate, parasite development rate, and vector competence are temperature sensitive. Importantly, we find qualitative and quantitative differences to the assumed temperature-dependent relationships. To explore the overall implications of temperature for transmission, we first use a standard model of relative vectorial capacity. This approach suggests a temperature optimum for transmission of 29°C, with minimum and maximum temperatures of 12°C and 38°C, respectively. However, the robustness of the vectorial capacity approach is challenged by the fact that the empirical data violate several of the model's simplifying assumptions. Accordingly, we present an alternative model of relative force of infection that better captures the observed biology of the vector-parasite interaction. This model suggests a temperature optimum for transmission of 26°C, with a minimum and maximum of 17°C and 35°C, respectively. The differences between the models lead to potentially divergent predictions for the potential impacts of current and future climate change on malaria transmission. The study provides a framework for more detailed, system-specific studies that are essential to develop an improved understanding on the effects of temperature on malaria transmission.
Conflict of interest statement
The authors have declared that no competing interests exist.
Figures
Fig 1. Gompertz model predictions for each…
Fig 1. Gompertz model predictions for each temperature and block combination overlaid on corresponding raw…
Fig 2. Dynamics of infectiousness over time…
Fig 2. Dynamics of infectiousness over time for each temperature and block combination.
Sporogony represented…
Fig 3
Predicted values for EIP 10 …
Fig 3
Predicted values for EIP 10 (light grey), EIP 50 (grey), and EIP 90 …
Fig 4. Mean length of the gonotrophic…
Fig 4. Mean length of the gonotrophic cycle (days) for each temperature.
Error bars represent…
Fig 5
Thermal performance curves for (A)…
Fig 5
Thermal performance curves for (A) biting rate, (B) vector competence, (C) mosquito mortality…
Fig 6. Curves for dynamic model of…
Fig 6. Curves for dynamic model of transmission potential for each temperature.
Area curves for…
Fig 7
(A) Best fit thermal performance…
Fig 7
(A) Best fit thermal performance curve for relative force of infection (here the…
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