title: Gametocyte dynamics and the role of drugs in reducing the transmission potential of Plasmodium vivax.
abstract: BACKGROUND
  Designing interventions that will reduce transmission of vivax malaria requires knowledge of Plasmodium vivax gametocyte dynamics.
  
  
  METHODS
  We analyzed data from a randomized controlled trial in northwestern Thailand and 2 trials in Papua, Indonesia, to identify and compare risk factors for vivax gametocytemia at enrollment and following treatment.
  
  
  RESULTS
  A total of 492 patients with P. vivax infections from Thailand and 476 patients (162 with concurrent falciparum parasitemia) from Indonesia were evaluable. Also, 84.3% (415/492) and 66.6% (209/314) of patients with monoinfection were gametocytemic at enrollment, respectively. The ratio of gametocytemia to asexual parasitemia did not differ between acute and recurrent infections (P = .48 in Thailand, P = .08 in Indonesia). High asexual parasitemia was associated with an increased risk of gametocytemia during follow-up in both locations. In Thailand, the cumulative incidence of gametocytemia between day 7 and day 42 following dihydroartemisinin + piperaquine (DHA + PIP) was 6.92% vs 29.1% following chloroquine (P < .001). In Indonesia, the incidence of gametocytemia was 33.6% following artesunate + amodiaquine (AS + AQ), 7.42% following artemether + lumefantrine, and 6.80% following DHA + PIP (P < .001 for DHA + PIP vs AS + AQ).
  
  
  CONCLUSIONS
  P. vivax gametocyte carriage mirrors asexual-stage infection. Prevention of relapses, particularly in those with high asexual parasitemia, is likely the most important strategy for interrupting P. vivax transmission.
authors.affiliation: Global Health Division, Menzies School of Health Research, Charles Darwin University, Darwin 0811, Australia.
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Douglas
authors.forename: Julie A
authors.initials: JA
authors.lastname: Simpson
authors.forename: Aung Pyae
authors.initials: AP
authors.lastname: Phyo
authors.forename: Hadjar
authors.initials: H
authors.lastname: Siswantoro
authors.forename: Armedy R
authors.initials: AR
authors.lastname: Hasugian
authors.forename: Enny
authors.initials: E
authors.lastname: Kenangalem
authors.forename: Jeanne Rini
authors.initials: JR
authors.lastname: Poespoprodjo
authors.forename: Pratap
authors.initials: P
authors.lastname: Singhasivanon
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Anstey
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: White
authors.forename: Emiliana
authors.initials: E
authors.lastname: Tjitra
authors.forename: Francois
authors.initials: F
authors.lastname: Nosten
authors.forename: Ric N
authors.initials: RN
authors.lastname: Price
mesh_terms: D000293:Adolescent; D000328:Adult; D000962:Antimalarials / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007214:Indonesia; D007223:Infant; D016780:Malaria, Vivax / Q000188:drug therapy* / Q000469:parasitology*; D008297:Male; D018512:Parasitemia / Q000517:prevention & control*; D010966:Plasmodium vivax / Q000187:drug effects*; D016032:Randomized Controlled Trials as Topic; D055502:Secondary Prevention; D013785:Thailand; D055815:Young Adult
chemical_list: D000962:Antimalarials
keywords: Plasmodium vivax; antimalarial drugs; epidemiology; gametocytes; transmission