Understanding how malaria spreads starts with understanding its vector. Malaria remains one of the world’s most persistent and deadly infectious diseases. Despite being preventable and treatable, it continues to claim hundreds of thousands of lives each year, particularly in sub-Saharan Africa. The disease itself is caused by a microscopic parasite of the genus Plasmodium, but it cannot reach humans without a vector; the female Anopheles mosquito. In simple terms, malaria is transmitted when an infected female Anopheles mosquito bites a human and injects the parasite into the bloodstream.

While the parasite causes the illness, the mosquito enables the transmission. Understanding the biology, behaviour, and habitat of the malaria vector is crucial to controlling and ultimately eliminating the disease.

Global distribution and habitat requirements

Malaria is endemic to large parts of the tropical and subtropical world. Regions most affected include sub-Saharan Africa, parts of Asia, the Middle East, Central and South America, and the Pacific islands. Africa accounts for the vast majority of global malaria cases and deaths; an estimated 95% of all malaria-related fatalities. The Anopheles mosquito species responsible for transmission are widespread in these areas. There are over 3,500 mosquito species globally, but only around 30 to 40 Anopheles species are considered effective malaria vectors. These mosquitoes have adapted to a range of environments, but their survival and ability to transmit malaria depend heavily on specific ecological conditions.

Like all mosquitoes, Anopheles species require water to complete their life cycle. Their eggs are laid in calm, shallow, and relatively clean bodies of water. Preferred breeding sites include natural depressions, puddles, ponds, rice paddies, hoof prints, ditches, and other small water collections. Temperature plays a critical role. Malaria transmission is only possible when the ambient temperature supports the full development of the parasite within the mosquito; a process that typically requires temperatures above 18°C. This is one of the reasons malaria transmission is seasonally driven in some regions and nearly absent in cooler climates. Humidity is another factor influencing mosquito survival. High humidity prolongs mosquito lifespan, increasing the chances that the parasite can mature and be transmitted to a new host during a subsequent blood meal.

Climate change impact on malaria

Malaria-carrying mosquitoes are highly sensitive to environmental conditions. Temperature, rainfall, and humidity all affect where mosquitoes can live and how quickly they develop. As the climate changes, these environmental factors are shifting, bringing mosquitoes into new areas where malaria was previously rare or non-existent. Warmer temperatures can shorten the time it takes for both mosquitoes and the malaria parasite to mature, potentially increasing transmission. Areas at higher altitudes or latitudes, once too cool for malaria mosquitoes, are now showing signs of suitability. While this doesn’t guarantee outbreaks, it raises concern for public health systems not accustomed to managing malaria risk. Climate change doesn’t just influence weather; it shapes disease patterns, and malaria is one of the most climate-sensitive infectious diseases we know.

Why the mosquito life cycle matters

Controlling malaria transmission requires more than treating infected people. It involves interrupting the parasite’s development at various stages, both in humans and in mosquitoes. Because the mosquito acts as an essential host for the parasite’s development, each phase of the mosquito’s life cycle offers a strategic point of intervention. Every stage of the life cycle presents an opportunity for targeted control, including environmental management, larviciding, insecticide spraying, and personal protection.

In this series, we will follow the Anopheles mosquito through its life; from aquatic beginnings to airborne adulthood, highlighting the features that make it a highly efficient malaria vector. By better understanding this mosquito’s biology and behaviour, we come closer to breaking the chain of transmission.

In the next article, we begin with the adults: how to distinguish males from females, what each feed on, their lifespan, and why all these differences matter for malaria and malaria control.

Click here to read the entire series.