Absence of K13 Propeller Domain Polymorphisms among Field Isolates Collected from the Brazilian Amazon Basin between 1984 and 2011.

Artemisinin resistance, presently confined to Southeast Asia and associated with mutations in the K13 (PfK13) propeller domain, represents a serious threat to global malaria control. This study aimed to provide baseline information for future artemisinin resistance surveillance, by analyzing the PfK13 propeller domain in field isolates collected from the Brazilian Amazon Basin between 1984 and 2011. A total of 152 mono-infections were assessed, of which 118 (78%) were collected before and 34 (22%) after the introduction of artemisinin-based combination therapy (ACT) in 2006. An 849-base pair fragment encoding the PfK13 propeller was amplified by nested polymerase chain reaction and sequenced in both directions. The sequences were compared with the reference sequence of 3D7. All samples showed wild-type sequences, thus, no mutations were observed. The results are in agreement with other recent reports and do not provide evidence for presence of PfK13 propeller domain polymorphisms associated with artemisinin resistance among field isolates in the Brazilian Amazon Basin neither before nor after the implementation of ACT.