Abstract: 【Abstract】 Objective  To identify the sources of infection and the mode of transmission of a malaria case with unknown origin.  Methods  Clinical data of the case were collected and the epidemiological investigation was conducted. The blood samples of the patient and the suspected infection source(blood donor) were detected by microscopy, rapid diagnostic test strip(RDT)and nested PCR.  Results The patient did not visited malaria endemic areas. After a blood transfusion, the patient had chills and fever, and was confirmed as falciparum malaria by microscopy with bone marrow and peripheral blood smears and RDT. The blood donor was a worker returned from Africa. Before blood donation she was sick like malaria carrier, and took anti-malarial drug. She was then confirmed as falciparum malaria by RDT and microscopy. The blood samples from the patient and the blood donor were diagnosed as falciparum malaria by nested PCR, and the similarity of the small subunit rRNA(SSU rRNA) sequence was 100%, showing they were mix-infected with K1 and MAD20 genotypes of Plasmodium falciparum.  Conclusion  This patient is confirmed P. falciparum infection via blood transfusion from a donor who returned from Africa.

Key words: Malaria, Blood transfusion, Tracing investigation