Malaria trends in Ethiopian highlands track the 2000 ‘slowdown’ in global warming

Rodó, Xavier; Martinez, Pamela P.; Siraj, Amir; Pascual, Mercedes

doi:10.1038/s41467-021-21815-y

Cited by 22 publications

(27 citation statements)

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“…For details on the method, see 46 and for other applications to malaria and climate forcing, see refs. 9 , 16 , 43 , 48 . This algorithm allows for consideration of both measurement and process noise, in addition to hidden variables, which are a typical limitation of surveillance records providing a single observed variable for the incidence.…”

Section: Methodsmentioning

confidence: 99%

The neglected role of relative humidity in the interannual variability of urban malaria in Indian cities

et al. 2022

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The rapid pace of urbanization makes it imperative that we better understand the influence of climate forcing on urban malaria transmission. Despite extensive study of temperature effects in vector-borne infections in general, consideration of relative humidity remains limited. With process-based dynamical models informed by almost two decades of monthly surveillance data, we address the role of relative humidity in the interannual variability of epidemic malaria in two semi-arid cities of India. We show a strong and significant effect of humidity during the pre-transmission season on malaria burden in coastal Surat and more arid inland Ahmedabad. Simulations of the climate-driven transmission model with the MLE (Maximum Likelihood Estimates) of the parameters retrospectively capture the observed variability of disease incidence, and also prospectively predict that of ‘out-of-fit’ cases in more recent years, with high accuracy. Our findings indicate that relative humidity is a critical factor in the spread of urban malaria and potentially other vector-borne epidemics, and that climate change and lack of hydrological planning in cities might jeopardize malaria elimination efforts.

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Section: Methodsmentioning

confidence: 99%

The neglected role of relative humidity in the interannual variability of urban malaria in Indian cities

et al. 2022

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“…In anoher recent study [ 16 ], authors have claimed that the dynamics of the monthly numbers of malaria ( Plasmodium falciparum ) cases were closely related to changes in minimum temperature levels in the region Oromia in Ethiopia, which increased until 1998, them, stabilized and declined from 2000 to 2005 (Fig. 1 ).…”

Section: Introductionmentioning

confidence: 99%

Epidemic malaria dynamics in Ethiopia: the role of self-limiting, poverty, HIV, climate change and human population growth

Krsulovic

Moulton

Lima

et al. 2022

Malar J

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Background During the last two decades, researchers have suggested that the changes of malaria cases in African highlands were driven by climate change. Recently, a study claimed that the malaria cases (Plasmodium falciparum) in Oromia (Ethiopia) were related to minimum temperature. Critics highlighted that other variables could be involved in the dynamics of the malaria. The literature mentions that beyond climate change, trends in malaria cases could be involved with HIV, human population size, poverty, investments in health control programmes, among others. Methods Population ecologists have developed a simple framework, which helps to explore the contributions of endogenous (density-dependent) and exogenous processes on population dynamics. Both processes may operate to determine the dynamic behaviour of a particular population through time. Briefly, density-dependent (endogenous process) occurs when the per capita population growth rate (R) is determined by the previous population size. An exogenous process occurs when some variable affects another but is not affected by the changes it causes. This study explores the dynamics of malaria cases (Plasmodium falciparum and Plasmodium vivax) in Oromia region in Ethiopia and explores the interaction between minimum temperature, HIV, poverty, human population size and social instability. Results The results support that malaria dynamics showed signs of a negative endogenous process between R and malaria infectious class, and a weak evidence to support the climate change hypothesis. Conclusion Poverty, HIV, population size could interact to force malaria models parameters explaining the dynamics malaria observed at Ethiopia from 1985 to 2007.

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“…The copyright holder for this preprint this version posted August 13, 2021. ; https://doi.org/10.1101/2021.08. 13.456216 doi: bioRxiv preprint…”

Section: Introductionmentioning

confidence: 99%

“…The WHO's 'Test procedures for insecticide resistance monitoring in malaria vector mosquitoes' advises that control programs select sentinel sites that will be representative of both the eco-epidemiological zones and malaria intensities in their region (11). However, both of these variables are changing over time-as a response to malaria interventions, and because of climate change and changing land use (12)(13)(14). Thus, sentinel sites may not accurately represent insecticide resistance within a region.…”

Section: Introductionmentioning

confidence: 99%

“…The copyright holder for this preprint this version posted August 13, 2021. ; https://doi.org/10.1101/2021.08.13.456216 doi: bioRxiv preprint the eco-epidemiological zones and malaria intensities in their region (11). However, both of these variables are changing over time-as a response to malaria interventions, and because of climate change and changing land use (12)(13)(14). Thus, sentinel sites may not accurately represent insecticide resistance within a region.…”

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Accounting for heterogeneity in wild adult samples to measure insecticide resistance in Anopheles malaria vectors

Holmdahl

Buckee

Childs

2021

Preprint

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Background Systematic, long-term, and spatially representative monitoring of insecticide resistance in mosquito populations is urgently needed to quantify its impact on malaria transmission, and to combat failing interventions when resistance emerges. Resistance assays on wild-caught adult mosquitoes (known as adult-capture) offer an alternative to the current protocols, and can be done cheaply, in a shorter time frame, and in the absence of an insectary. However, quantitative assessments of the performance of these assays relative to the gold standard, which involves rearing larvae in an insectary, are lacking. Methodology/Principal findings We developed a discrete-time deterministic mosquito lifecycle model to simulate insecticide resistance assays from adult-captured mosquito collection in a heterogeneous environment compared to the gold standard larval capture methods, and to quantify possible biases in the results. We incorporated non-lethal effects of insecticide exposure that have been demonstrated in laboratory experiments, spatial structure, and the impact of multiple exposure to insecticides and natural ageing on mosquito death rates during the assay. Using output from this model, we compared the results of these assays to true resistance as measured by the presence of the resistance allele. In simulated samples of 100 test mosquitoes, reflecting WHO-recommended sample sizes, we found that compared to adult-captured assays (MSE = 0.0059), larval-captured assays were a better measure of true resistance (MSE = 0.0018). Using a correction model, we were able to improve the accuracy of the adult-captured assay results (MSE = 0.0038). Bias in the adult-capture assays was dependent on the level of insecticide resistance rather than coverage of bed nets or spatial structure. Conclusions/Significance Using adult-captured mosquitoes for resistance assays has logistical advantages over the standard larval-capture collection, and may be a more accurate sample of the mosquito population. These results show that adult-captured assays can be improved using a simple mathematical approach and used to inform resistance monitoring programs.

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Malaria trends in Ethiopian highlands track the 2000 ‘slowdown’ in global warming

Cited by 22 publications

References 84 publications

The neglected role of relative humidity in the interannual variability of urban malaria in Indian cities

The neglected role of relative humidity in the interannual variability of urban malaria in Indian cities

Epidemic malaria dynamics in Ethiopia: the role of self-limiting, poverty, HIV, climate change and human population growth

Accounting for heterogeneity in wild adult samples to measure insecticide resistance in Anopheles malaria vectors

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