title: [Longitudinal surveillance of chloroquine resistance of Plasmodium falciparum after cessation of medication in south Yunnan].
abstract: The resistance of P. falciparum to chloroquine was assayed by in vitro microtest in 1981 and after cessation of medication in 1984, 1988-1990 and 1992 in south Yunnan Province of China. The resistance rates were 97.4% (38/39), 100% (25/25), 96.1% (73/76) and 93.7% (59/63), respectively; ID50 were 170, 132, 125 and 110 nmol/L; ID95 were 1,000, 740, 707 and 576 nmol/L; mean dosages for complete inhibition of schizont formation were 55.4, 46.7, 45.8 and 35.4 (pmol/well). A comparison of the results in 1981, 1984, 1988-1990 and 1992, the resistance rate showed no marked change, ID50 dropped 22.3% (P < 0.05), 26.4% (P < 0.05) and 35.3% (P < 0.01); ID95 declined 26.0% (P < 0.05), 29.3% (P < 0.05) and 42.2% (P < 0.01); mean dosage of inhibition dropped 15.7% (P > 0.05), 17.3% (P < 0.05) and 36.1% (P < 0.01). The results show that the extent of resistance in chloroquine-resistant P. falciparum to chloroquine in south Yunnan has been declined markedly, indicating that coresistance was variable and dropped along with the declining of drug pressure.
authors.affiliation: Institute of Malaria Prevention and Treatment of Yunnan Province, Simao.
authors.forename: H L
authors.initials: HL
authors.lastname: Yang
authors.forename: P F
authors.initials: PF
authors.lastname: Yang
authors.forename: Y
authors.initials: Y
authors.lastname: Dong
authors.forename: L G
authors.initials: LG
authors.lastname: Che
authors.forename: W C
authors.initials: WC
authors.lastname: Chen
authors.forename: H
authors.initials: H
authors.lastname: He
authors.forename: D Q
authors.initials: DQ
authors.lastname: Liu
authors.forename: R J
authors.initials: RJ
authors.lastname: Liu
authors.forename: B
authors.initials: B
authors.lastname: Zhan
authors.forename: C Y
authors.initials: CY
authors.lastname: Zhang
mesh_terms: D000818:Animals; D002681:China; D002738:Chloroquine / Q000494:pharmacology*; D004351:Drug Resistance; D008137:Longitudinal Studies; D010963:Plasmodium falciparum / Q000187:drug effects*
chemical_list: D002738:Chloroquine