Laboratory detection of imported Plasmodium ovale wallikeri in Sichuan Province

Abstract

To identify 10 imported cases of Plasmodium ovale wallikeri infection in Sichuan Province from January to April in 2018, and to analyze the P. ovale wallikeri infection status of 1 079 malaria cases reported in this area from 2013 to 2017. The 10 cases collected in 2018 were examined by microscopy, RDT, nested PCR and sequencing. Meanwhile, the retrospective detections of P. ovale wallikeri of the 1 079 blood samples from past 5 years were conducted by nested PCR using wallikeri-specific primers. For the 10 cases, the microscopic examinations were all positive for P. ovale, of which 2 were mixed infection with P. falciparum, and the results of RDT were all positive for Plasmodium. Except for 2 cases of P. falciparum infection, the routine nested PCR showed negative results for rest of the samples. The nested PCR for the specific detection of P. ovale wallikeri showed the 10 cases were all positive, and the following sequencing confirmed that the 10 cases were all infected with P. ovale wallikeri. The retrospective tests discovered 2 cases both reported in 2017 and recorded as simple P. falciparum infection tuned out to be mixed infection with P. falciparum and P. ovale wallikeri. This is the first time that imported P. ovale wallikeri infection is founded in Sichuan Province.