title: Can treatment of P. vivax lead to a unexpected appearance of falciparum malaria?
abstract: Of 994 patients admitted to the Bangkok Hospital for Tropical Diseases for P. vivax malaria, 104 (10.5%) experienced appearance of Plasmodiumfalciparum following drug treatment for P. vivax . In all patients, P. falciparum parasites were not found by microscopic examination upon admission. The mean time for P. falciparum appearance was 12.6 days after the commencement of chloroquine treatment. Patients experiencing appearance of P. falciparum had significantly lower hematocrit, and greater initial P. vivax parasite counts. We use a mathematical model to explore the consequences of chloroquine treatment of such mixed infections. Both clinical results and features of the model suggest that such "hidden infections" may be quite common, and that the appearance of P. falciparum may be stimulated by treatment of P. vivax.
authors.affiliation: Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. dmason@itsa.ucsf.edu
authors.forename: D P
authors.initials: DP
authors.lastname: Mason
authors.forename: S
authors.initials: S
authors.lastname: Krudsood
authors.forename: P
authors.initials: P
authors.lastname: Wilairatana
authors.forename: P
authors.initials: P
authors.lastname: Viriyavejakul
authors.forename: U
authors.initials: U
authors.lastname: Silachamroon
authors.forename: W
authors.initials: W
authors.lastname: Chokejindachai
authors.forename: P
authors.initials: P
authors.lastname: Singhasivanon
authors.forename: S
authors.initials: S
authors.lastname: Supavej
authors.forename: F E
authors.initials: FE
authors.lastname: McKenzie
authors.forename: S
authors.initials: S
authors.lastname: Looareesuwan
mesh_terms: D000328:Adult; D000818:Animals; D000962:Antimalarials / Q000627:therapeutic use*; D002738:Chloroquine / Q000627:therapeutic use*; D006801:Humans; D016778:Malaria, Falciparum / Q000150:complications* / Q000453:epidemiology; D016780:Malaria, Vivax / Q000150:complications / Q000188:drug therapy* / Q000453:epidemiology; D008297:Male; D010963:Plasmodium falciparum / Q000187:drug effects / Q000302:isolation & purification; D010966:Plasmodium vivax / Q000187:drug effects / Q000302:isolation & purification; D013785:Thailand / Q000453:epidemiology
chemical_list: D000962:Antimalarials; D002738:Chloroquine