High Frequency of Deletions in the pfhrp 2 and pfhrp 3 Genes of Plasmodium falciparum in the Middle Rio Negro Region of the Brazilian Amazon.

Several countries are reporting natural populations of P. falciparum with deletions in the pfhrp 2/3 genes that can lead to false-negative results in rapid diagnostic tests. To investigate the prevalence of deletion in the pfhrp 2/3 genes in the Rio Negro basin in the Brazilian Amazon and identify whether there is clinical differentiation between individuals infected by these parasites, clinical samples collected from 2003 to 2016 were analyzed from symptomatic and asymptomatic P. falciparum -infected individuals. The molecular deletion of pfhrp2 and pfhrp3 genes was evaluated using the protocols recommended by the WHO. From 82 samples used, 28 (34.2%) had a single deletion in pfhrp 2, 19 (23.2%) had a single deletion in pfhrp 3, 15 (18.3%) had a double deletion ( pfhrp2/3 ), and 20 (24.4%) did not have a deletion in either gene. In total, 29.3% of individuals had an asymptomatic plasmodial infection and were 3.64 times more likely to have parasites with a double deletion ( pfhrp 2/3) than patients with clinical malaria ( p = 0.02). The high prevalence of parasites with pfhrp 2/3 deletions shows the need to implement a surveillance program in this area. Deletions in parasites may be associated with the clinical pattern of the disease in this area. More studies must be carried out to elucidate these findings.