Non-falciparum malaria imported mainly from Africa: a review from a Portuguese hospital.

Background: Non-falciparum malaria (NFM) has been reported to be responsible for around 25% of imported malaria cases in Europe but is often neglected due to its less severe clinical course when compared to Plasmodium falciparum. Differentiation between species is however crucial for a correct approach. The objective of this study is to report the cases of this often missed aetiology of malaria in a tertiary hospital in Portugal.

Methods: Data were retrospectively analysed from patients admitted from January 2006 to August 2016 with a NFM diagnosis based on microscopy, rapid diagnostic tests (RDT) (BinaxNow) and/or PCR. Epidemiologic and clinical aspects were reviewed.

Results: A total of 19 NFM cases were diagnosed, corresponding to 8.4% of the total 225 cases of malaria. Seventeen (89%) were male with a median age of 41 years. All but one case were imported from sub-Saharan Africa, with 12 (63%) of the cases returned from Angola. Microscopy was positive for all patients and correctly identified the species in 12 (63%) patients. BinaxNOW was performed in all patients and it was positive in 11 cases, showing a sensitivity of 58%. PCR was performed in nine patients and was positive in eight of them, being responsible for the identification of the species in four cases. Plasmodium malariae accounted for 37% (n = 7) of the cases, Plasmodium ovale for 32% (n = 6) and Plasmodium vivax for 17% (n = 3). In three (16%) patients, morphology was suggestive of P. vivax or P. ovale, but precise species identification was not possible. Regarding presentation, fever was the most reported symptom, and the most frequent laboratory finding was thrombocytopaenia. Quinine-doxycycline was prescribed in eleven patients (58%), chloroquine in six cases (32%) and artemether-lumefantrine in two (11%). All of the patients showed clinical improvement.

Conclusions: NFM remains an important cause of imported malaria in patients from sub-Saharan Africa, alone or as mixed infection with P. falciparum. Access to PCR techniques facilitates diagnosis, as low sensitivity from RDTs and microscopy are to be expected.