Misdiagnosis of imported malaria from African areas due to an increased prevalence of gene deletion: the Djibouti case.

Following the diagnosis of a malaria case imported from Djibouti and not detected by a pfHRP2-based rapid diagnostic test (RDT), we investigated the prevalence of the -deleted parasites in Djibouti using 378 blood samples collected between January and May 2019, from Djiboutian patients with suspected malaria. Malaria diagnosis by quantitative PCR confirmed the presence of for 20.9% (79/378) samples while RDTs did not detect HRP2 antigen in 83.5% (66/79) of these samples. Quantitative PCRs targeting the genes confirmed the absence of both genes for 86.5% of strains. The very large number (86.5%) of f parasites lacking the genes observed in this study, now justifies the use of non-HRP2 alternative RDTs in Djibouti. In this area and in most countries where HRP2-based RDTs constitute the main arsenal for malaria diagnosis, it is important to implement a systematic surveillance and to inform biologists and clinicians about the risk of malaria misdiagnosis. Further investigations are needed to better understand the mechanism of selection and diffusion of the -deleted parasites.