Europe is experiencing a surge in malaria cases caused by mosquitoes transported by airplanes.

After malaria was eradicated in Western Europe during the 1970s, most cases reported in EU/EEA countries were solely among travelers returning from malaria-endemic regions. Of the 6,131 cases recorded in the EU/EEA in 2022, 99% were travel-related.

Local transmission cases are reported annually in Western Europe. These include imported infections transmitted by local mosquitoes after biting an infected returning traveler, whose blood contains Plasmodium; induced cases linked to other transmission routes, such as healthcare-associated infections or mother-to-child transmission; and "Odyssean" malaria, which refers to cases caused by bites from infected mosquitoes that arrived by airplane, luggage, or parcels from endemic areas.

A systematic review analyzed data from studies conducted in Europe from 1969 to January 2024, sourced from MEDLINE, Embase, and OpenGrey databases. The data was supplemented by inquiries to health authorities in the EU/EEA and the UK for information from 2022.

Out of 145 reported cases from nine countries, 105 were classified as airport malaria, 32 as luggage malaria, and eight as both types. The majority of cases were recorded in France, Belgium, and Germany, with half of the affected individuals residing or working near or within an international airport. It was found that the number of malaria cases originating from airports and luggage is on the rise: over the past five years, they accounted for one-third of all reported cases, even despite the reduction in air travel during the COVID-19 pandemic.

The average age of individuals infected with malaria was 37.9 years, with a higher prevalence among men than women (ratio of 1.5:1). In 124 cases with known outcomes, patients recovered, while nine died. The deceased patients were, on average, older, with a mean age of 57.2 years. Forty-eight of the 145 cases were epidemiologically linked to at least one other case.

Similar trends were observed in a retrospective analysis of surveillance data and investigations of local malaria infections in France from 1995 to 2022. Cases were classified by the most likely mode of transmission using a classification developed by the European Centre for Disease Prevention and Control (ECDC). A descriptive analysis was also conducted to identify spatiotemporal patterns.

Researchers identified a total of 117 local malaria infection cases reported in the European part of France. They also established that the overall rate of locally acquired infections remains stable, with an increasing number of "Odyssean" malaria cases reported since 2011. Fifty-one of the 117 identified cases were classified as "Odyssean" malaria, 36 as induced, 27 as hidden (when the investigation was inconclusive), and three as imported.

Among patients with locally acquired malaria, severe cases and deaths were observed more frequently than in imported cases.

To mitigate the risk of imported malaria, researchers from the retrospective analysis conducted in France recommended stringent monitoring of aircraft disinfection. To improve treatment, they also advised healthcare providers to consider the possibility of local malaria infection in patients with unexplained fever, even in the absence of travel history.

The authors of the systematic review emphasized the need for more structured surveillance of malaria cases in Europe. They also recommended implementing preventive measures and evaluating the effectiveness and adherence to existing protocols.