Al-Shamahy Hassan, Al-Harazy Abdullilah Hussein, Harmal Nabil S, Al-Kabsi Abdulgodos M
Department of Medical Microbiology, University of Sana'a, Yemen.
Ann Saudi Med. 2007 Nov-Dec;27(6):432-6. doi: 10.5144/0256-4947.2007.432.
Unpublished studies on antimalarial drug efficacy have found low levels of chloroquine resistance in Yemen. This study was carried out to determine the current prevalence of drug resistance in Plasmodium falciparum in Yemen to the main anti-malarial drugs and to determine the effective concentration(EC) values.
The WHO standard protocol was used for the selection of subjects, collection of blood samples, culture techniques, examination of post-culture blood slides and interpretation of results. The in vitro micro-test Mark III was used for assessing susceptibility of P. falciparum isolates.
The criteria for blood parasite density was met by 219 P. falciparum malaria patients. Chloroquine resistance was found in 47% of isolated P. falciparum schizonts. Mefloquine resistanfce was found in 5.2%. In addition, the EC50 and EC95 values in blood that inhibited schizont maturation in resistant isolates were higher than the normal therapeutic level of mefloquine. No resistance occurred against quinine or artemisinin, with no growth at hte cut-off level of quinine and inhibition of low concentrations of artemisinin.
Our study confirmed the occurrence of chloroquine-resistant P. falciparum and a slow increase in the rate of this resistance; it is likely that resistance will increase further and spread over all the foci of malaria in Yemen. The low rate of mefloquine-resistant P. falciparum, was lower than that reported in Africa or Southeast Asia, but it is the first report of mefloquine resistance in Yemen. Finally, the isolates were sensitive to low-concentrations of quinine and artemisinin.
关于抗疟药疗效的未发表研究发现也门存在低水平的氯喹耐药性。本研究旨在确定也门恶性疟原虫对主要抗疟药物的耐药性现状，并确定有效浓度（EC）值。
采用世界卫生组织标准方案进行受试者选择、血样采集、培养技术、培养后血涂片检查及结果判读。使用体外微量试验Mark III评估恶性疟原虫分离株的敏感性。
219例恶性疟原虫疟疾患者符合血中寄生虫密度标准。在分离出的恶性疟原虫裂殖体中，47%发现有氯喹耐药性。甲氟喹耐药性为5.2%。此外，耐药分离株中抑制裂殖体成熟的血液中EC50和EC95值高于甲氟喹的正常治疗水平。对奎宁或青蒿素未出现耐药性，在奎宁的截止水平无生长，低浓度青蒿素具有抑制作用。
我们的研究证实了恶性疟原虫氯喹耐药性的存在及其耐药率的缓慢上升；耐药性可能会进一步增加并在也门所有疟疾疫源地传播。恶性疟原虫甲氟喹耐药率较低，低于非洲或东南亚报道的水平，但这是也门甲氟喹耐药性的首次报告。最后，分离株对低浓度奎宁和青蒿素敏感。
