Multiple P. vivax relapses: challenges for management in a reference center outside the transmission area in Brazil
Background: Plasmodium vivax relapses occur due to activation of hypnozoites. Primaquine is the only available drug effective for radical treatment of malaria. Methods: review of three patients suffering multiple (2-5) relapses of P. vivax acquired in the Amazon region followed in Fiocruz, RJ, a reference center outside the endemic area. Results: Case 1: 32y, male, 78 kg, resided in São Gabriel da Cachoeira/AM for 2 years, presented vivax malaria treated with Chloroquine and Primaquine in November/2015. Moving to Rio de Janeiro, was diagnosed with P. vivax malaria in 25/01/2016. He was treated with CQ and PQ (3.5mg/kg divided in 9 days). In 16/04/2016, presented a new clinical malaria episode diagnosed and P. vivax and was treated with CQ and PQ (7m/kg, in 16d). He did not present new episodes since (updated 30/03/2017). Case 2: 33y, female, wife of patient #1. Resided in São Gabriel da Cachoeira/AM, until 14/11/2015 where had received treatment for vivax malaria in October/2015. Back in Rio de Janeiro, was diagnosed with P. vivax malaria in 18/02/2016 and was treated with CQ and PQ (3.5mg/kg in 7d). In 05/04/2016 presented a new diagnosis of vivax malaria. CQ and PQ (7m/kg in 7d) was prescribed without further episodes (updated 30/03/2017). Case 3: 56y, male, 82kg, resided in Machadinho do Oeste/RO, for 2 months until 04/08/2016 where received treatment for vivax malaria in July/2016. He presented new episodes of vivax malaria in 22/08/2016, 24/11/2016, 28/01/2017 and 20/03/2017. For these episodes, the respective treatment was administered: CQ + PQ (3.5mg/kg in 9d), CQ+PQ (3.5mg/kg in 18d), CQ+PQ (7mg/kg in 14d) and (Artemether-Lumefantrine + PQ (7mg/kg in 14d). CYP2D6 genotype was performed and classified as slow metabolizer. The patient is still under follow-up (update 30/03/2017) Conclusion: There is a challenge of managing recurring vivax malaria episodes. Follow-up outside the endemic region provides the advantage of more clearly characterizing recurrences of relapses. Herewith we present 3 cases of multiple relapses occurring despite adequate drug dosing. Factors such as adequate dosing, adherence, drug quality and pharmacogenetics can impact the effectiveness of radical cure of P. vivax infection and need to be properly evaluated.