The importance of the contribution of rapid test, serological and molecular methods in the diagnosis of two imported malaria cases with atypical microscopy.
Malaria is a widespread and life-threatening disease in tropical and subtropical regions. In patients with typical clinical symptoms, malaria is considered as a preliminary diagnosis if there is a travel history to malaria-endemic areas. The basis of the laboratory diagnosis of malaria is the microscopic examination of Giemsa stained smears. On the other hand, the diagnosis and differentiation of Plasmodium species with microscopic examination may have some difficulties. In the first case, adifferent appearance from the classical Plasmodium vivax erythrocytic forms in infected erythrocytes were detected in 1% of all erythrocytes in thin smear blood preparations of a 26-year-old male with complaints of fever and chills and a story of travel to Nigeria. It was observed that parasitic nuclei were not prominent, and were located in the cytoplasm irregularly as chromatin or dye particles, nucleus fragments similar to Schüffner's granules in the form of scattered and granular spots were present in some erythrocytes, the cytoplasm of some Plasmodium erythrocytic forms were irregular and nuclei were not seen. There were no Schüffner's granules in any of the infected erythrocytes. P.vivax was detected by the rapid diagnostic test (OptiMAL, DiaMed GmbH, Switzerland), which searches for the antigens of Plasmodium species, in the peripheral blood sample of the patients. The P.vivax 18S rRNA gene was also detected by the multiplex real-time polymerase chain reaction. Antibodies against Plasmodium species were searched by using the Pan Malaria Antibody CELISA (CeLLabs Pty Ltd, Brookvale, Australia) kit in the patient's serum sample and the optical density (OD) value of the patient sample was measured five times the OD value of the positive control. In the second case, adifferent appearance from the classical P.falciparum erythrocytic forms in infected erythrocytes were detected in 12% of all erythrocytes in thin smear blood preparations of a 31-year-old male who has been suffering from persistent fever, severe headache, pain in the eyes and was known to be working in Nigeria. It was observed that some Plasmodium trophozoites have 1/3 of the size of erythrocytes such as P.vivax and have non-granular cytoplasm, some erythrocytic forms were round and the nucleus and cytoplasm were hardly distinguished, some of them were seen as crescent and close to the nucleus of the cytoplasm and some erythrocytic forms had characteristically a single nucleus and a scattered cytoplasm, similar to mature trophozoites of P.vivax. Although the Plasmodium young trophozoites were similar to P.vivax in means of magnitude, the forms in which the nuclei adhered to the erythrocyte wall were common. There were no P.falciparum gametocyte forms. P.falciparum like young trophozoite was observedonly in one of the four smears. P.falciparum was detected by the commercial rapid diagnostic test and P.falciparum 18S rRNA gene was also detected by the multiplex real-time polymerase chain reaction. Antibody formation against Plasmodium species was not detected in the ELISA test. In these case reports, the importance of the support of rapid diagnostic tests, serological and molecular methods to microscopic diagnosis and species determination of two imported malaria cases were demonstrated.