Malaria is a febrile disease caused by Plasmodium parasites and usually transmitted by mosquitos. In 2020, almost half of the global population was at risk of contracting malaria and over 400 000 humans die yearly of the disease, with sub-Saharan Africa’s population being most at risk. In Europe, 50 years after eradication, malaria is still a major health concern. While most infections in Europe are related to international travel, climatic changes are foreseen to enhance the risk for locally transmitted malaria infections in Europe in the future.

Malaria notification rate (map) and reported cases (graph) in Europe
Source: ECDC, 2023, Surveillance Atlas of Infectious Diseases

Notes:

Map and graph show data for the EEA member and cooperating countries, excluding Liechtenstein, Switzerland and Türkiye due to absence of data. The boundaries and names shown on this map do not imply official endorsement or acceptance by the European Union.
The disease is notifiable at the EU level, but the reporting period varies among the countries.
When countries report zero cases, the notification rate on the map is shown as '0'. When countries have not reported on the disease in a particular year, the rate is not visible in the map and is labelled as 'unreported' (last updated in April 2023).

Source & transmission

Malaria infections are caused by Plasmodium parasites. Five Plasmodium species exist that infect humans, of which P. ciparum and vivax are the most common and cause the highest disease burden (Loy et al., 2017; WHO, 2022). Typically, the disease is transmitted by the bite of a female Anopheles mosquito that carries Plasmodium cells in its blood. The Anopheles mosquitos are, compared to other mosquito species present in Europe, relatively small and slim, with an inclined posture. Most Anopheles species are active at night, but some also bite at dusk or in the early morning (WHO, 2022).

Anopheles are widely distributed across all continents except Antarctica, but the malaria parasite (Plasmodium spp.) does not occur in all these regions. Nevertheless, the large distribution range of the mosquito makes it possible for the disease to expand globally. Malaria was successfully eliminated from Europe 50 years ago by draining marshes, administrating prophylactic drugs to the population and spraying insecticides (Boualam, et al., 2021). In Southern Europe, however, malaria re-emerged in 2003 with a low number of locally transmitted cases since then, although the vast majority of infections (>99%) is still related to travel (Bertola et al., 2022; WHO, 2022). Evidence exists for the presence of Anopheles mosquitos in 33 European countries (ECDC, 2022a,b,c), albeit generally in low numbers so with a limited risk for large malaria outbreaks. In Northern Europe, Anopheles mosquitos are absent from Denmark, Iceland and Norway, but were observed in Finland and Sweden in 2020 (Bertola et al., 2022; Lilja et al., 2020). People can also get infected at home or in airports via mosquitos traveling in suitcases.

In addition, injection or transfusion of infected blood, or the use of contaminated needles and syringes can also transmit malaria. Maternal transmission, from mother to the unborn child, is rare.

Health effects

Patients develop symptoms of malaria infections usually one to two weeks after a mosquito bite. Yet, delayed primary infections may occur, albeit rarely, 6 to 12 months later (Trampuz et al., 2003). During the first 2-3 days of the illness, malaria symptoms are usually nonspecific, including fatigue, headache, and pain in joints, muscles, stomach and chest, often leading to misdiagnoses. A slowly rising fever typically develops, the main symptom of malaria. The disease then progresses to a shaking chill and high fever, generally accompanied by headache, back pains, diarrhoea or nausea and sometimes profuse sweating. After a fever-free interval, the cycle of chills, fever and sweating recurs. An untreated primary attack may last from a week to a month or more. Sometimes - often after inadequate treatment or infection with drug-resistant parasites - parasite cells of P. vivax or P. ovale remain dormant in the liver and trigger renewed malaria attacks at irregular intervals months or years later (Trampuz et al., 2003). Without medical treatment, there is a likelihood of the malaria infection becoming severe or even fatal in a course of hours or days, particularly P. falciparum-infections may progress fast (Basu and Sahi, 2017). Patients rapidly show worse symptoms, including acute brain infection (cerebral malaria), anaemia, low blood sugar levels or high blood acidity. In rare cases malaria may progress to yellow pigmentation of skin and tissues, kidney failure, or even shock when no sufficient blood flow can be maintained. Severe malaria is a possible cause of coma. In areas with many transmissions, P. falciparum can infect the placenta and cause severe anaemia, miscarriage, premature birth or low birth weight (Basu and Sahi, 2017).

Morbidity and mortality in Europe

In the EEA member countries (excluding Liechtenstein, Switzerland and Türkiye due to absence of data):

  • 66,013 malaria infections were recorded between 2008 and 2018, of which the majority was confirmed.
  • Between 2011 and 2018 the number of cases steadily increased.
  • The number of autochthonous cases increased between 2014 and 2017, reaching 18 cases in 2017 and falling back to 14 in 2018. Most of the autochthonous cases were detected in Greece, France, Spain and Italy.

(ECDC, 2014-2020)

Distribution across population

  • Age group with the highest disease rate in Europe: 25 – 44 years old (ECDC, 2014-2020)
  • Groups at higher risk of severe disease course: infants and children under five, pregnant women, people with low immunity
  • Groups at higher risk of infection: migrant workers and travellers
  • The rate of confirmed malaria cases is higher among men than women

Climate sensitivity

Climatic suitability

The Plasmodium parasite survives in mosquitos in a temperature range between 15.4 and 35 °C. Malaria transmitting mosquitos prefer the monthly precipitation to be above 80 mm and the monthly relative humidity above 60% (Benali et al., 2014). The optimal temperature for Anopheles mosquito populations is 29 °C. Their capacity to transmit malaria decreases gradually above or below this temperature (Villena et al., 2022).

Seasonality

In Europe, peaks in the number of malaria cases occur in the summer months July to September. Since the vast majority of malaria cases is imported, this could at least partly be linked to travellers returning from summer holidays (ECDC, 2014-2020).

Climate change impact

Development of the Plasmodium parasite within a mosquito is faster in warmer climates (Grover-Kopec et al., 2006). Shortening of the incubation time, induced by global warming, has the potential to greatly increase the infection risk (Beck-Johnson et al., 2013). In addition, Anopheles mosquitos are expected to shift northwards and to higher altitudes due to global warming (Hertig et al., 2019). In Europe, previously unaffected regions will most likely experience an increase in malaria incidence. Furthermore, higher temperatures, precipitation intensity and air humidity will result in larger Anopheles populations, hence increasing transmission capacity. The active mosquito season is projected to extend, larvae will grow faster, populations will survive more easily, and bite rates will increase, hence enhancing the risk for malaria infections (Grover-Kopec et al., 2006). Increased rainfall can also create more suitable habitats for mosquitos. The Southern and the South-eastern parts of Europe are at risk to become part of the distribution range of Anopheles mosquitos, with some species already been detected in Spain, Portugal, Italy, the Balkans. Also, other countries, including France, Greece, Spain, Bulgaria, Serbia and Ukraine, may experience more locally transmitted Plasmodium infections with climatic changes (Beck-Johnson et al., 2013; Fischer et al., 2020). On the contrary, in Northern and Western Europe, even with rising temperatures due to climate change, the risk of malaria may not increase as long as current urbanization and wetland loss trends continue to eliminate reproduction sites for mosquitos (Piperaki and Daikos, 2016).

Notwithstanding increased infection risks, climate change impacts on malaria infections are foreseen to be low as long as there are well-functioning health systems, which are very capable of detecting and treating malaria.

Prevention & Treatment

Prevention

  • Personal protection: long-sleeved clothes, mosquito repellents, nets or screens, and avoidance of mosquito habitats
  • Mosquito control: environmental management, e.g., minimizing reproduction opportunities in open natural and artificial waters, and biological or chemical measures (e.g., see the activities of the mosquito control action group in Germany). Yet, mosquito resistance to insecticides is a problem.
  • Awareness raising about disease symptoms, disease transmission and mosquito bite risks
  • Active monitoring and surveillance of mosquitos, disease cases and environment to prevent transmission (e.g. see the case studies of the ‘Mückenatlas’ initiative or the EYWA project)
  • Chemoprophylaxis for travellers to malaria-endemic areas

Treatment

  • Combination therapy with antimalarial drugs to (i) eliminate parasites and (ii) prevent mild symptoms from becoming severe. Yet, antimalarial drug resistance is a global threat to malaria control efforts

References

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Beck-Johnson, L. M. et al., 2013, The Effect of Temperature on Anopheles Mosquito Population Dynamics and the Potential for Malaria Transmission, PLoS ONE 8(11), e79276. https://doi.org/10.1371/journal.pone.0079276

Benali, A. et al., 2014, Satellite-derived estimation of environmental suitability for malaria vector development in Portugal, Remote Sensing of Environment 145, 116–130. https://doi.org/10.1016/j.rse.2014.01.014

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