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Investigation of an airport-associated cluster of falciparum malaria in Frankfurt, Germany, 2022

Journal Contribution - Journal Article

Malaria is a parasitic disease caused by Plasmodium species and affects an estimated 247 million patients in 84 countries worldwide [1]. Since 1974, Europe has been considered malaria-free, and in 1964 the World Health Organization (WHO) certified Germany free of indigenous malaria [2]. Today, the overwhelming majority (99.8%) of the 8,000–9,000 annual cases in Europe are travel-associated and the yearly incidence rate is 1.2 cases per 100,000 inhabitants [3]. In Germany, where malaria is a notifiable disease, 999 cases were reported in 2019. In Europe, the notified cases decreased significantly during the coronavirus disease 2019 (COVID-19) pandemic (366 notified cases in 2020) [3]. After the travel restrictions were lifted, an increase of severe malaria cases was reported [4], the reason of which remains unclear to date.

Autochthonous malaria transmission can occur when the parasite and a competent vector population meet. This was demonstrated in 2011 in Greece in a P. vivax outbreak linked to seasonal workers from malaria-endemic countries [5,6]. Non-imported malaria in non-endemic areas can occur congenitally, via blood transfusions or organ transplants and at airports [7]. Potential modes of transmission are either by endemic mosquitoes of Anopheles species with ingested gametocytes from carriers or imported Plasmodium-infected mosquitoes (Odyssean malaria) [8].
Tracing the origins of airport malaria can be challenging if there is either no direct airport connection [9] or it is the only risk factor for transmission [10]. Recent cases caused by imported Anopheles species in the vicinity of airports did not lead to further transmission [11,12]. However, airport malaria has increased in Europe [13]. Epidemiological modelling indicates that in the decades to come, a spread of vector-competent species northwards and a possible re-emergence of autochthonous malaria in southern Europe is likely due to climate change [14,15].

As malaria is mainly a tropical disease, without relevant travel histories, the diagnosis can be missed. To prevent adverse or fatal outcomes, a rapid diagnosis is essential.
Journal: Eurosurveillance
ISSN: 1560-7917
Issue: 5
Volume: 29
Publication year:2024
Accessibility:Open