Invasive Mosquito Pushes Malaria Into Africa’s Cities

Horn of Africa · Public Health

Anopheles stephensi in Africa is moving malaria from the countryside into the city. The invasive Asian mosquito, first detected in Djibouti in 2012, is now spreading across the continent and breeding in the water infrastructure of fast-growing urban centres.

Malaria in Africa has long been a rural disease, transmitted mainly by Anopheles gambiae and Anopheles funestus. Public-health systems, from bed nets to indoor spraying, were built around that reality.

Anopheles stephensi breaks the model. It thrives in man-made water containers and construction sites, rests indoors and outdoors, bites throughout the day and feeds readily on livestock as well as people.

From Djibouti to Ghana

The species was first detected on the continent in Djibouti City in 2012. Since then, malaria morbidity and mortality in the country have risen sharply, and the mosquito has spread through the Horn of Africa.

Researchers now track it as far west as Ghana. Its expansion follows trade routes, urban growth and the water-storage habits of cities where piped supply is unreliable.

A July 2026 study in Parasites & Vectors provided the confirmation health agencies feared. Of 196 An. stephensi caught in Djibouti City, two carried Plasmodium vivax sporozoites, and their genetic signature matched the dominant invasive haplotypes circulating across the Horn of Africa.

A decade of silent spread

The invasion has been a decade in the making. After Djibouti in 2012, detections followed in Ethiopia in 2016, in Sudan and Somalia by 2019, in Kenya in late 2022 and most recently in West Africa, with Ghana confirming the species in 2024.

The World Health Organization issued a vector alert on the species in 2019 and upgraded its warnings as the detections multiplied. Each new finding has arrived years after the mosquito had already established itself locally.

The Djibouti study adds a sharper edge because of the parasite involved. Most malaria in sub-Saharan Africa is caused by Plasmodium falciparum, but Djibouti’s transmission is dominated by the vivax strain, which hides in the liver and can relapse months after treatment.

A city-adapted vector carrying vivax complicates elimination strategy across the Horn.

The urbanisation of malaria

An Ethiopian systematic review published this year quantified the shift. Across epidemiological studies, An. stephensi accounted for a pooled 51% of Anopheles mosquitoes sampled, with near-total dominance in southeastern districts.

That matters because Ethiopia’s cities were previously considered low-risk. A vector that breeds in water storage turns urban density from protection into exposure.

Kenya is responding early. KEMRI and the National Malaria Control Programme are running national surveillance for the species, using the Community Health Promoter network to map its spread before it becomes entrenched.

Why existing tools fall short

Bed nets protect people at night, but An. stephensi bites during the day. Indoor residual spraying targets mosquitoes that rest on walls after feeding indoors, a habit this species does not reliably share.

Livestock feeding adds another blind spot. Farms and peri-urban cattle can sustain mosquito populations even where human-focused control is strong.

Genetic surveillance adds urgency to the response. The invasive haplotypes found in Djibouti show the mosquito travels with human trade rather than natural dispersal, which puts a premium on monitoring ports, road corridors and construction supply chains.

Modelling work in Tanzania suggests larviciding, treating the water where mosquitoes breed, could close part of the gap, including drone-assisted mapping of breeding sites. But most African cities have no larviciding infrastructure at scale.

What to watch

First, whether the World Health Organization escalates its guidance on urban malaria in response to the Djibouti transmission findings. National programmes watch Geneva before reallocating budgets.

Second, westward spread. Detection in Ghana means West Africa’s megacities, from Accra to Lagos, are now on the invasion pathway.

Third, funding. Malaria programmes are already stretched by drug resistance and donor fatigue, and a new vector arrives as the continent fights the Ebola emergency tracked in The Rio Times DR Congo outbreak coverage and across its Eastern Africa section.

The lesson of the past decade is that detection always lags establishment. The cities that act before their first confirmed case will spend far less than those that wait.

Frequently Asked Questions

What is Anopheles stephensi?
Anopheles stephensi is a malaria-transmitting mosquito native to South Asia and the Middle East. First detected in Africa in Djibouti in 2012, it has spread across the Horn of Africa and as far west as Ghana.

Why is Anopheles stephensi dangerous for African cities?
Unlike native malaria vectors, it breeds in urban water tanks, wells and construction sites and bites during the day. That brings malaria risk into densely populated cities that were previously considered low-risk.

Has Anopheles stephensi been proven to transmit malaria in Africa?
Yes. A July 2026 study in Parasites & Vectors found Plasmodium vivax sporozoites in stephensi mosquitoes collected in Djibouti City, confirming transmission, and Ethiopian studies show the species now dominates some districts.

Can current malaria controls stop it?
Only partly. Bed nets and indoor spraying were designed for night-biting, indoor-resting native species. Researchers point to larviciding of urban breeding sites, including drone-assisted mapping, as a necessary addition.

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