Malaria transmission in non-endemic areas: case report, review of the literature and implications for public health management

In non-endemic areas, malaria is rare and locally acquired infections, particularly with Plasmodium falciparum, are exceptional events. The diagnosis is, therefore, likely to be delayed or missed in patients without a relevant travel history. This report describes a case of falciparum malaria in Berlin, Germany, in a patient who had not been to an endemic area for more than a decade. Potential routes of vector-related and direct transmission were evaluated, particularly with regard to a possible danger to the public. A review of the literature was conducted regarding possible routes of transmission and their probability assessed. Genotyping of parasite isolates of this and another patient with malaria admitted 16 days before revealed homology between the two strains. In a local entomological survey, anopheline vectors on the hospital grounds as well as in the residential area of both patients were found. Despite intensive investigations, the mode of transmission remained obscure. In this context, possible routes of vector-borne and direct occupational/accidental transmission in a major European city are reviewed and discussed, providing information and guidance in case other similar events occur elsewhere. Examples for investigations and measures to be taken in such a situation are provided. When local malaria transmission within a large non-immune population cannot be ruled out, genotyping of parasite isolates, local entomological surveys, preparedness for secondary cases, expert consultations in a multidisciplinary team and careful information management are essential. Malaria acquired in non-endemic areas remains an unlikely, but possible event for which awareness needs to be maintained.