[Longitudinal surveillance of chloroquine resistance of Plasmodium falciparum after cessation of medication in south Yunnan].
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.
Yang
H L
HL
Institute of Malaria Prevention and Treatment of Yunnan Province, Simao.
Yang
P F
PF
Dong
Y
Y
Che
L G
LG
Chen
W C
WC
He
H
H
Liu
D Q
DQ
Liu
R J
RJ
Zhan
B
B
Zhang
C Y
CY
D000818:Animals; D002681:China; D002738:Chloroquine / Q000494:pharmacology*; D004351:Drug Resistance; D008137:Longitudinal Studies; D010963:Plasmodium falciparum / Q000187:drug effects*
D002738:Chloroquine