title: Treatment of vivax malaria on the western border of Thailand.
abstract: The efficacy of chloroquine (25 mg base/kg over 3 days) in Plasmodium vivax malaria was evaluated in 1995/96 in 342 patients living in an endemic area on the western border of Thailand. Clearance of fever and parasites was obtained within 2 days in > 95% of the patients, and all were aparasitaemic by day 4. Reappearance of P. vivax occurred in 1 patient on day 21 and in 8 by day 28, giving a 28-day cure rate of 97% [95% confidence interval (CI) 95-99%]. By day 63, the relapse/re-infection rate was 63% (95% CI 57-69%). Most reappearances of parasitaemia (85%; 121/143) were symptomatic. These patients were retreated either with chloroquine alone (n = 70) or with chloroquine and primaquine (0.25 mg/kg daily for 14 days) (n = 43). Only 1 patient (in the chloroquine-only group) had prolonged parasite clearance (D8) and he developed recurrent P. vivax by day 21 suggesting possible recrudescence. The addition of primaquine to chloroquine reduced the risk of having a third vivax episode within 2 months by 96% (95% CI 83-99%). This resulted in a significantly higher haematocrit at day 42 despite a greater decrease in haematocrit during the first week of treatment with chloroquine-primaquine (P = 0.04). Chloroquine remains highly effective on the western border of Thailand and the use of strictly supervised primaquine effectively prevents relapse. The introduction of primaquine on a large scale in an endemic area still requires a long-term risk-benefit assessment which must take into account potential toxicity, low compliance and reductions in the incidence and severity of P. falciparum infections by co-existent P. vivax.
authors.affiliation: Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: C
authors.initials: C
authors.lastname: Luxemburger
authors.forename: M
authors.initials: M
authors.lastname: van Vugt
authors.forename: S
authors.initials: S
authors.lastname: Jonathan
authors.forename: R
authors.initials: R
authors.lastname: McGready
authors.forename: S
authors.initials: S
authors.lastname: Looareesuwan
authors.forename: N J
authors.initials: NJ
authors.lastname: White
authors.forename: F
authors.initials: F
authors.lastname: Nosten
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000962:Antimalarials / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D002738:Chloroquine / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016780:Malaria, Vivax / Q000188:drug therapy* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010966:Plasmodium vivax / Q000302:isolation & purification; D011319:Primaquine / Q000627:therapeutic use; D012008:Recurrence; D013785:Thailand / Q000453:epidemiology; D016896:Treatment Outcome
chemical_list: D000962:Antimalarials; D002738:Chloroquine; D011319:Primaquine