title: [Therapeutic response of Plasmodium vivax to chloroquine in Bolivia].
abstract: BACKGROUND
  Knowledge of the therapeutic efficacy of chloroquine for Plasmodium vivax infections improves the capacity for surveillance of anti-malarial drug resistance.
  
  
  OBJECTIVE
  The therapeutic efficacy of chloroquine as treatment was evaluated for uncomplicated Plasmodium vivax malaria in Bolivia.
  
  
  METHODS
  An in vivo efficacy study of chloroquine was undertaken in three regions of Bolivia--Riberalta, Guayaramerín and Yacuiba. Two hundred and twenty-three patients (84, 80, and 59 in the three regions, respectively) aged over 5 years old were administered with chloroquine (25 mg/kg/three days) and followed for 28 days. Blood levels of chloroquine and desethylchloroquine were measured on day 2 and on the day of reappearance of parasitemia. The cumulative incidence of treatment failure was calculated using the Kaplan and Meier survival analysis.
  
  
  RESULTS
  The mean parasitemias (asexual) on day 0 were 6,147 parasites/μl of blood in the Riberalta population, 4,251 in Guayaramerín and 5,214 in Yacuiba. The average blood concentrations of chloroquine-desethylchloroquine during day 2 were 783, 817, and 815 ng/ml, respectively. No treatment failures were observed in Yacuiba, whereas in Riberalta and Guayaramerín, the frequencies of treatment failures were 6.2% and 10%. Blood levels of chloroquine and desethylchloroquine in patients with treatment failure showed values below 70 ng/ml on the day of reappearance of parasitemia.
  
  
  CONCLUSIONS
  Resistance of Plasmodium vivax to chloroquine was not demonstrated in three regions of Bolivia.
authors.affiliation: Organización Mundial de la Salud, Organización Panamericana de la Salud, La Paz, Bolivia. aanez@bol.ops-oms.org
authors.forename: Arletta
authors.initials: A
authors.lastname: Añez
authors.forename: Dennis
authors.initials: D
authors.lastname: Navarro-Costa
authors.forename: Omar
authors.initials: O
authors.lastname: Yucra
authors.forename: Cecilia
authors.initials: C
authors.lastname: Garnica
authors.forename: Viviana
authors.initials: V
authors.lastname: Melgar
authors.forename: Manuel
authors.initials: M
authors.lastname: Moscoso
authors.forename: Ricardo
authors.initials: R
authors.lastname: Arteaga
authors.forename: Gladys
authors.initials: G
authors.lastname: Nakao
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000962:Antimalarials / Q000097:blood / Q000627:therapeutic use*; D001838:Bolivia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D002738:Chloroquine / Q000031:analogs & derivatives / Q000097:blood / Q000627:therapeutic use*; D004351:Drug Resistance; D005260:Female; D006801:Humans; D016780:Malaria, Vivax / Q000188:drug therapy* / Q000453:epidemiology / Q000469:parasitology; D008297:Male; D008875:Middle Aged; D059208:Parasite Load; D018512:Parasitemia / Q000188:drug therapy* / Q000453:epidemiology / Q000469:parasitology; D010966:Plasmodium vivax / Q000187:drug effects*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000188:drug therapy / Q000453:epidemiology / Q000469:parasitology; D012424:Rural Population; D055815:Young Adult
chemical_list: D000962:Antimalarials; D002738:Chloroquine; C007278:desethylchloroquine