Malaria was eradicated across Europe, yet several Anopheles mosquitoes remain widespread. This article explains which species matter, why imported cases rarely spark local spread, and how climate change may shift the picture.
Malaria in Europe today
Malaria is caused by parasites of the genus Plasmodium. Six species infect people: P. falciparum, P. vivax, P. ovale wallikeri, P. ovale curtisi, P. malariae and P. knowlesi. Infected female Anopheles mosquitoes transmit the parasite. Around 60 to 100 anopheline species worldwide can carry malaria (ECDC). Other routes exist but are rare: blood transfusion, organ transplantation, needle sharing and congenital infection. Symptoms include fever and influenza-like signs such as chills, headache, muscle pain and malaise. Severe disease can bring cerebral malaria, kidney failure and lasting neurological problems. Nearly all cases reported by EU and EEA countries are imported, so malaria is mainly a travel medicine concern. A few locally acquired cases appear each year, including introduced cases detected since 2009. French Guiana remains endemic.
Why Europe is not malaria free by geography alone
During the twentieth century malaria was eliminated from many temperate regions, including the whole of Europe. The parasites did not vanish because the mosquitoes disappeared. Four Anopheles species are named as historically important European vectors: Anopheles atroparvus, Anopheles labranchiae, Anopheles sacharovi and Anopheles plumbeus. These species remain widespread across the continent, or are suspected of having contributed to past transmission. That history matters because a competent vector plus an imported infection can, in principle, produce a local case. The European Centre for Disease Prevention and Control judges the current risk as relatively small where health systems can detect and treat malaria promptly. Climate change could allow reappearance, but functioning surveillance and clinical care carry more weight than temperature alone.
Anopheles atroparvus, the coastal survivor
Anopheles atroparvus ranges from south-eastern Sweden to Portugal along the Atlantic coast, and around the Baltic and Mediterranean Seas. It is reported from more than twenty European countries but is absent from southern Italy and Greece (ECDC). It is considered the most common and abundant mosquito in Portugal. Females hibernate in stables or dwellings, though Portuguese populations show a shorter winter diapause and stay active through winter. The species can fly at least three kilometres (ECDC). Larvae prefer brackish, sunlit water rich in filamentous algae or floating vegetation, but also use fresh water canals, ditches, rice fields and pools. It is generally zoophilic yet bites people readily. In 1943 it was linked to over 340 000 cases in Spain (ECDC).
A refractory vector with limits
Anopheles atroparvus was responsible for winter malaria transmission in Britain and coastal parts of the Netherlands and Germany at the start of the twentieth century. Spain was certified free of malaria in 1963 (ECDC). Despite that record, the species is refractory to tropical strains of Plasmodium falciparum. Laboratory infection succeeded only once, using strain NF54, at 13.5% infection prevalence and a mean of 14 oocysts per infected female (ECDC). This matters for risk assessment. The mosquito can act as a bridge when an imported infection arrives in a region it inhabits, but the chance of onward spread is low. A single imported case is therefore a public health event worth investigating rather than a signal of returning endemic malaria.
Anopheles plumbeus and artificial breeding sites
Anopheles plumbeus occurs throughout Europe, the Caucasus, the Middle East, Iran, Iraq and North Africa, and is present in almost all European countries. It breeds classically in water-filled tree holes with high salt concentration and low oxygen in beech, birch, oak and elm. It also develops in artificial containers such as tyres, rainwater casks and cemetery vases, in catch basins and septic tanks, and in abandoned manure tanks and uncleaned stables with broken roofing. It is a known persistent biter of people, most active at dusk and dawn, but some populations bite heavily in daylight and show strong preference for human blood. Suspected involvement is recorded in two locally acquired cases in London, two in Germany and cases among forest workers in Croatia (ECDC).
An efficient carrier near people
Laboratory infection of Anopheles plumbeus females from Switzerland with a tropical strain of Plasmodium falciparum reached 94% infectivity. The species is described as an efficient carrier of Eurasian strains of Plasmodium vivax and tropical strains of Plasmodium falciparum. It is still judged of minor importance in transmission because of its ecology, though its adaptation to urban breeding sites is a growing concern. Schaffner and colleagues, writing in Malaria Journal in 2012, reported landing rates in Alsace reaching 365 individuals in 15 minutes. In experimental infections using 293 field-caught females, sporozoite infection prevalence ranged from 31 to 88%, similar to Anopheles gambiae at 67 to 97%, although oocyst loads were lower. They concluded it can significantly raise transmission risk.
Climate shifts and what surveillance must watch
Elke Hertig, writing in Parasites and Vectors in 2019, modelled six dominant Anopheles vectors under future climate change. Under current conditions Anopheles atroparvus occupies 38% of the study area and Anopheles messeae 65.4%. The projections indicate a northward spread of vectors, while occurrence in parts of the Mediterranean may decline as rainfall falls. Vector stability shows the largest increases for southern and south-eastern Europe, naming Spain, southern France, Italy, Greece, Bulgaria, Romania, and southern Ukraine and Russia. Hertig stresses that population growth, urbanisation, migration and economic development must enter future risk assessments. Malaria elimination depends substantially on health infrastructure and socioeconomic conditions, not climate alone. Hertig also reports that climate alone cannot determine malaria risk, because elimination depends on health infrastructure and socioeconomic conditions that shape how quickly imported infections are detected and treated in each country.
Sources
- Disease information about malaria, ECDC: European Centre for Disease Prevention and Control
- Anopheles atroparvus, factsheet for experts: European Centre for Disease Prevention and Control
- Anopheles plumbeus, factsheet for experts: European Centre for Disease Prevention and Control
- Anopheles plumbeus (Diptera: Culicidae) in Europe: a mere nuisance mosquito or potential malaria vector?: Malaria Journal
- Distribution of Anopheles vectors and potential malaria transmission stability in Europe and the Mediterranean area under future climate change: Parasites and Vectors