Plasmodium vivax malaria infection diagnosed by indirect fluorescent antibody test.

We present the diagnostically challenging case of a 51-year-old Japanese male who visited Papua New Guinea for one month. Approximately a month after returning to Japan, he experienced a high fever. Malaria was suspected and he was admitted to Tsukuba University Hospital. Although the blood smear did not reveal the malarial parasite, a diagnosis of malaria was made using an indirect fluorescent antibody test (IFAT). The patient was treated and discharged but symptoms returned three months later. This time, the blood smear was positive for malarial parasites. IFAT was useful in this case for the early diagnosis of Plasmodium vivax and for ruling out infection by Plasmodium falciparum.