[Changes in chloroquine resistance of Plasmodium falciparum in Hainan province].
OBJECTIVE
To observe the variation in resistance of Plasmodium falciparum after the cessation of chloroquine medication.


METHODS
WHO standard in vitro microtest and in vivo test were used.


RESULTS
In vitro test showed that the rate of chloroquine-resistant P. falciparum dropped from 97.9% in 1981 to 26.7% in 1997 (P < 0.001). The mean concentration of chloroquine for complete inhibition of schizont formation declined from 10.46 +/- 7.14 pmol/ul blood in 1981 to 1.63 +/- 1.47 pmol/microliter blood in 1997(P < 0.001). In vivo test showed that the rate of chloroquine-resistant P. falciparum decreased from 84.2% in 1981 to 18.4% in 1997(P < 0.001). The proportion of R III cases to the total resistant cases dropped from 53.1% in 1981 to 14.3% in 1997.


CONCLUSIONS
A tendency of progressive decline of resistance of the parasite was revealed after the cessation of chloroquine medication.
Liu
D
D
Institute of Parasitic Diseases, Chinese Academy of Preventive Medicine, Shanghai 200025.
Cai
X
X
Ren
D
D
Liu
R
R
Lin
S
S
Zeng
L
L
Tang
X
X
D000293:Adolescent; D000328:Adult; D000818:Animals; D002648:Child; D002675:Child, Preschool; D002681:China; D002738:Chloroquine / Q000494:pharmacology*; D004351:Drug Resistance; D006801:Humans; D016778:Malaria, Falciparum / Q000188:drug therapy / Q000469:parasitology; D008875:Middle Aged; D010963:Plasmodium falciparum / Q000187:drug effects*
D002738:Chloroquine