Belgium and the globalization of malaria

A very interesting malaria case was reported in the CDC Emerging Infectious Diseases journal (open access). Theunissen et al. describe a patient who contracted Plasmodium falciparum malaria in Belgium despite not having  visited any malaria endemic area for nine years! What happened here? A number of possibilities exist. Relapse from a previous infection is not possible with falciparum, which unlike the vivax and ovale species of malaria parasites, does not have a “dormant” stage. However, there may have been chronic, low-grade infection acquired nine years ago which remained asymptomatic until now. A few cases of >1 year delay between initial exposure and clinical symptoms have been reported, but a nine year delay would be quite rare. A second explanation could be indigenous malaria transmission by local anopheline species – i.e. a Belgian mosquito bites an infected returning traveler and then bites our patient. Mini-outbreaks have occurred in Florida and Texas, where malaria used to be endemic and conditions are still ripe for transmission. In this case, which occurred in winter, the report claims it is too cold to have many mosquitoes flying around (and I would add too cold for P. falciparum to complete its life cycle in any mosquitoes which were present). Blood transfusion, intravenous drug use, or accidental needle stick injuries can also transmit P. falciparum, but none of these exposures were present here. One key detail is left: two weeks ago (a classic incubation period for malaria), a friend visiting from Guinea-Conakry stayed with the patient. Airport/luggage/container malaria describes the transmission of malaria from an infected mosquito which is accidentally imported during travel. In the end, none of the explanations can be proved definitively, though the authors believe “suitcase malaria” was probably responsible. They then conclude:

This case highlights the problem of diagnosing P. falciparum malaria in patients without a recent travel history to malaria-endemic areas.

A tangential rant – what is certainly not difficult though is diagnosing malaria when a recently returned traveler from West Africa presents with fever and malaise. Unfortunately,  the student health service at my university told a friend of mine that she had viral pneumonia and gave her ibuprofen. Luckily, someone else correctly diagnosed her later, and she lived. Barely.

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