Prevention, vector control, and climate

What is climate change and how is it impacting malaria trends globally?

Climate change is the combination of changing temperature and global weather trends; climate change has been mainly driven by human activity since the 1800s. Changing temperature and weather trends have many downstream impacts, one of which is malaria transmission. Malaria is transmitted through mosquitos (specifically female “Anopheles mosquitos”) to humans. Mosquitos thrive in warmer and wetter climates, and so, as temperature increases and rainfall increases, so do malaria-carrying mosquitoes.There’s an indicator called the “Climatic Suitability for Malaria Transmission”, or CSMT. This is defined as “the coincidence of precipitation accumulation greater than 80 mm, average temperature between 18°C and 32°C, and relative humidity greater than 60%”. Precipitation (i.e. rainfall), temperature, and humidity all impact how many Anopheles mosquitos are in the area by influencing their feeding patterns. More rainfall, hotter temperature, and high humidity mean that there is more potential for malaria-carrying mosquitoes to be around.

What work is being done to learn more about this and combat it?

Africa

• The Kenya Medical Research Institute (KEMRI) works with the US Centers for Disease Control and Prevention (CDC) to collect routine data on malaria interventions, incidence, and other related indicators. Through this data, KEMRI is able to paint a picture of how malaria trends are being impacted by climate change.  
• AMREF is working with the WHO Regional Office for Africa to implement regional initiatives that address the health impacts of climate change. An emphasis is being put on taking a health systems approach, which means that action must involve players across health sectors – the government, non-government organizations, community organizations, and academic institutions alike. Relatedly, the Africa CDC endorses a one-health approach to tackling the impacts of climate change on health outcomes.

Asia

• The National Institute of Malaria Research (NIMR) in India is paving the way for malaria elimination through three key research themes: parasite-host biology, vector biology, and epidemiology & environmental biology. Noting the importance of data integration and visualization, the NIMR has pieced together a malaria dashboard to understand epidemiological trends over time and how they may be impacted by climate change.
• The National Vector Control and Surveillance Unit (NVC&S) of the Ministry of Health (MoH) in Indonesia is working with the WHO to build local capacity related to health entomology (the study of disease-carrying insects) in high risk regions such as Papua, East Nusa Tenggara (NTT), East Kalimantan and North Maluku. These Indonesian health entomologists are then able to understand malaria-carrying mosquitoes’ behaviour, and track how their behaviour is being impacted by climate change.

Latin America & The Caribbean

• The Project for Malaria Control in Andean Border Areas (PAMAFRO) helped decrease malaria transmission in Peru, up until 2011, when funding for this program started decreasing and annual rainfall in the country began increasing. The importance of environmental factors in influencing the burden of malaria, particularly the presence of water and rainfall, has been noted in Peru, among other Amazonian regions.
• In Venezuela, the ongoing transmission of malaria has been attributed, in part, to deforestation linked to illegal gold mining activities. Environmental degradation works synergistically with increasing temperature, meaning that the effect of hotter temperatures on malaria transmission is greater in regions with higher mining activity.

Learn more by checking out these resources:

• Malaria hotspots and climate change trends in the hyper-endemic malaria settings of Mizoram along the India–Bangladesh borders: https://www.nature.com/articles/s41598-023-31632-6
• Is the threat of malaria increasing?: https://www.gatesfoundation.org/ideas/articles/malaria-threat-climate-change
• Climate change and malaria: predictions becoming reality: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(23)01569-6/fulltext
• FEELING THE HEAT: https://www.science.org/content/article/malaria-cases-could-ebb-even-hotter-world-other-diseases-will-get-worse
• Malaria is thriving in Kenya thanks to climate change: https://www.gavi.org/vaccineswork/malaria-thriving-kenya-thanks-climate-change
• How Climate Change Is Spreading Malaria in Africa: https://www.nytimes.com/2023/02/14/health/malaria-mosquitoes-climate-change.html
• Climate change and malaria: some recent trends of malaria incidence rates and average annual temperature in selected sub-Saharan African countries from 2000 to 2018: https://malariajournal.biomedcentral.com/articles/10.1186/s12936-023-04682-4

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Indoor residual spraying for preventing malaria in communities using insecticide‐treated nets

This article discusses a review of studies conducted since 2008 in sub-Saharan Africa, focusing on indoor residual spraying (IRS) as a method for preventing malaria in communities where insecticide-treated nets are also used. The review included eight cluster-randomized controlled trials (cRCTs), one controlled before-and-after (CBA) study, and one interrupted time series (ITS) study.

Indoor residual spraying for preventing malaria

This study assesses the effectiveness of indoor residual spraying (IRS) as a standalone intervention in preventing malaria. Additionally, the study aims to compare the relative effects of IRS versus the use of insecticide-treated nets (ITNs) on important malaria-related parameters.

The Malaria Control Success Story

A narrative that highlights significant achievements and progress in the field of malaria control. It emphasizes successful strategies, interventions, or programs that have led to substantial reductions in malaria cases, deaths, or transmission in a particular region or country.

How to detect, treat and prevent malaria:  A guide for ASHA and other community volunteers in districts with a high burden of malaria

This guide provides ASHA and community volunteers in high malaria burden areas with essential steps for detecting, treating, and preventing malaria. It covers symptom recognition, proper drug administration, prevention measures like ITNs, data reporting, and the importance of ongoing training to effectively combat malaria.

Preventing Childhood Malaria in Africa by Protecting Adults from Mosquitoes with Insecticide-Treated Nets

This paper suggests a strategy that involves safeguarding adults from mosquito bites using insecticide-treated nets as a means to reduce childhood malaria in Africa. This approach recognizes that by protecting adults, who may act as reservoirs for malaria parasites, transmission to children can also be minimized.

Combining indoor residual spraying and insecticide-treated nets for malaria control in Africa: a review of possible outcomes and an outline of suggestions for the future 

This article reviews the potential outcomes of integrating indoor residual spraying (IRS) and insecticide-treated nets (ITNs) as strategies for malaria control on the African continent.

Effectiveness of long-lasting insecticidal nets in prevention of malaria among individuals visiting health centres in Ziway-Dugda District, Ethiopia: matched case–control study

This study presents findings from a matched case-control study assessing the efficiency of long-lasting insecticidal nets (LLINs) in preventing malaria among individuals seeking care at health centers in Ziway-Dugda District, Ethiopia. 

Threats to the effectiveness of insecticide-treated bednets for malaria control: thinking beyond insecticide resistance

This viewpoint discusses the challenges and issues that go beyond insecticide resistance in the context of using insecticide-treated bednets for malaria control.

Preventing Childhood Malaria in Africa by Protecting Adults from Mosquitoes with Insecticide-Treated Nets

This paper suggests a strategy that focuses on safeguarding adults from mosquito bites using insecticide-treated nets to reduce childhood malaria cases in Africa. 

Effectiveness of insecticide-treated bednets in malaria prevention in Haiti: a case-control study

This study presents the findings of research conducted to assess the effectiveness of insecticide-treated bednets (ITNs) in preventing malaria in Haiti. It compares individuals who have contracted malaria (cases) with those who have not (controls) to evaluate the impact of ITN use on malaria prevention in this specific context.

Insecticide-treated bed nets and curtains for preventing malaria (Review)

This document presents a comprehensive review of the use of insecticide-treated bednets and curtains as interventions for preventing malaria. It examines various studies and research findings to evaluate the effectiveness of these interventions in reducing malaria transmission.

WHO guidelines for malaria

This document outlines various aspects of malaria prevention, including vector control (such as the use of insecticide-treated bednets and indoor residual spraying), co-deployment of interventions, supplementary measures, and research needs.

 Prevention and Control

This guideline provides facilitators with comprehensive information and tools to promote malaria prevention and control within local communities. It offers practical strategies, resources, and techniques that facilitators can use to empower communities to take proactive measures against malaria.

Comparison of house spraying and insecticide-treated nets (ITNs) for malaria control

This document discusses a comparison between residual house spraying and insecticide-treated nets (ITNs) as methods for controlling malaria vectors.