Anopheles stephensi and the impending challenge to malaria eradication in Africa

Dear Editor,

Malaria remains a formidable global health threat [1]. Despite significant progress in malaria eradication efforts, the emergence of Anopheles stephensi in Africa poses a critical challenge to the ongoing initiatives [2]. This mosquito species, traditionally found in Asia, has demonstrated adaptability to African environments, threatening to reverse the gains made in malaria control. While many African countries have made strides in controlling malaria, achieving elimination remains a challenge due to identifiable steps and unpredictable progression.

Anopheles stephensi, traditionally an Asian malaria vector, has become an alarming threat in Africa. Its unique characteristics, such as thriving in urban areas, resistance to pesticides, and laying eggs in artificial water sources, set it apart from other vectors [3]. The unexpected outbreak in Ethiopia in 2023 highlighted the urgency of addressing this invasive mosquito's presence [3]. The genetic and immunological factors of Anopheles stephensi, including changes in the APL1 immune factor, contribute to its adaptability [4]. Additionally, the mosquito's ecological and behavioral characteristics, such as breeding in urban water storage tanks, influence its potential as a malaria vector.

Limited knowledge about Anopheles stephensi's bionomics hampers eradication efforts. Challenges include identifying saline-tolerant larvae, establishing identification keys, overcoming insecticide resistance, and addressing climate change implications. Additionally, the lack of centralized data and varying political will across affected countries complicates surveillance.

Climate and environmental factors, including temperature preferences, play a pivotal role in Anopheles stephensi's emergence. Its ability to adapt to urbanization and exploit human-built water storage facilitates its spread. Additionally, rising temperatures and changing precipitation patterns influence the mosquito's abundance. Studies suggest that Anopheles stephensi could increase annual P. falciparum malaria cases by 50% if strategic interventions are not implemented [3, 4]. Mapping thermal transmission suitability using satellite imagery becomes crucial for predicting its spread and informing targeted interventions. Current vector control strategies, recommended by WHO, may need augmentation to combat Anopheles stephensi effectively. Challenges include limited surveillance, human behavior influencing transmission, and the need for tailored control measures in different communities. Resistance to conventional treatments and climate change further complicate control efforts.

Collaborative efforts are essential for tackling the Anopheles stephensi invasion. Countries like Mauritius and the United States have employed a One Health approach and multi-state collaboration, respectively, to strengthen surveillance and control. However, technical limitations and varied political will among affected countries remain challenges. The emergence of Anopheles stephensi in Africa poses a multifaceted challenge to malaria eradication efforts. Understanding its profile, characteristics, and the factors contributing to its spread is crucial for devising targeted control strategies. Collaborative international efforts, coupled with ongoing research, are imperative to address the complex dynamics of this invasive vector and ensure continued progress in the fight against malaria in Africa.

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Not applicable.

Availability of data and materials

Data sharing is not applicable to this article as no datasets were generated or analysed during the current study.

Funding

No funding was received for this study.

CRediT authorship contribution statement

Gbolahan Olatunji: Writing – review & editing, Writing – original draft, Conceptualization. Emmanuel Kokori: Writing – review & editing, Writing – original draft. Julia Mimi Kwape: Writing – review & editing, Writing – original draft, Conceptualization. Doyin Olatunji: Writing – review & editing, Writing – original draft. Chidera Stanley Anthony: Writing – review & editing, Writing – original draft. Ikponmwosa Jude Ogieuhi: Writing – review & editing, Writing – original draft. Jessica Uchechi Damian: Writing – review & editing, Writing – original draft. Israel Charles Abraham: Writing – review & editing, Writing – original draft. Stephen Chukwuemeka Igwe: Writing – review & editing, Writing – original draft. Oreoluwa Alabi: Writing – review & editing, Writing – original draft, Conceptualization. Nicholas Aderinto: Writing – review & editing, Writing – original draft, Conceptualization.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Handling Editor: Patricia Schlagenhauf

List of abbreviations

WHO

World Health Organization

NMCP

National Malaria Control Program

P. falciparum

Plasmodium falciparum

APL1

Anopheles Plasmodium-responsive leucine-rich repeat 1

US

United States

GIS

Geographic Information System

DNA

Deoxyribonucleic Acid