Liu D Q, Liu R J, Ren D X, Gao D Q, Zhang C Y, Qui C P, Cai X Z, Ling C F, Song A H, Tang X
Institute of Parasitic Diseases, Chinese Academy of Preventive Medicine, Shanghai.
Bull World Health Organ. 1995;73(4):483-6.
In 1979, in view of the widespread resistance of Plasmodium falciparum to chloroquine in the island of Hainan, China, it use as an antimalarial was suspended throughout the island. A longitudinal survey of the chloroquine-sensitivity of P. falciparum was carried out over the period 1981-91 to investigate whether its resistance had changed from the 1979 level. In-vitro assays were carried out every 2-3 years, while in-vivo tests were performed annually over the period 1981-83 and also in 1991. Resistance to chloroquine declined progressively after its use had stopped. The in-vitro tests indicated that the rate of chloroquine-resistant P. falciparum was 97.9% in 1981, but dropped to 60.9% in 1991 (P < 0.001). The mean concentration of chloroquine for complete inhibition of schizont formation was 10.4 pmol/microliters in 1981, but decreased to 3.0 pmol/microliters in 1991 (P < 0.001). The proportion of samples taken from malaria cases that required high concentrations ( > 6.4 pmol/microliters) of chloroquine for complete inhibition of schizont formation was 83.3% in 1981, but only 17.4% in 1991 (P < 0.001); at low concentrations ( > 1.6 pmol/microliters), the corresponding proportions increased from 4.2% in 1981 to 60.8% in 1991 (P < 0.001). In the 4-week in-vivo test, the rate of chloroquine-resistant P. falciparum decreased from 84.2% in 1981 to 40% in 1991 (P < 0.001). RII + RIII cases represented 59.4% of the total resistant cases in 1981, but decreased to 37.5% in 1991 (0.02 > P > 0.01).
1979年，鉴于中国海南岛恶性疟原虫对氯喹的广泛抗性，全岛暂停将氯喹用作抗疟药。1981年至1991年期间，对恶性疟原虫的氯喹敏感性进行了纵向调查，以研究其抗性是否已从1979年的水平发生变化。每2至3年进行一次体外试验，而在1981年至1983年期间以及1991年每年进行体内试验。氯喹停用后，其抗性逐渐下降。体外试验表明，1981年恶性疟原虫对氯喹的抗性率为97.9%，但在1991年降至60.9%（P<0.001）。1981年完全抑制裂殖体形成所需氯喹的平均浓度为10.4 pmol/微升，但在1991年降至3.0 pmol/微升（P<0.001）。从疟疾病例中采集的样本中，完全抑制裂殖体形成需要高浓度（>6.4 pmol/微升）氯喹的比例在1981年为83.3%，但在1991年仅为17.4%（P<0.001）；在低浓度（>1.6 pmol/微升）下，相应比例从1981年的4.2%增加到1991年的60.8%（P<0.001）。在为期4周的体内试验中，恶性疟原虫对氯喹的抗性率从1981年的84.2%降至1991年的40%（P<0.001）。RII+RIII病例在1981年占抗性病例总数的59.4%，但在1991年降至37.5%（0.02>P>0.01）。
