柬埔寨西部检测出对青蒿素耐药的疟原虫(原创翻译)

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New York（Reuters Health）7月31日消息—一项新的研究表明，从柬埔寨西部分离出来的恶性疟原虫中，青蒿素耐药的很常见，而且体外检测的结果不准确。另一项新研究发现，接种完整子孢子可以预防疟疾。这两项研究发表于7月30号出版的新英格兰医学杂志中。
最新研究发现，在泰国和柬埔寨边界，青蒿素治疗正在对恶性疟原虫失效。这一地区之前已有恶性疟原虫对抗疟药物发生耐药的报道。
在第一项研究中，曼谷马依多尔大学的Arjen M. Dondorp教授及其同事，在柬埔寨西部的40名患者和泰国西北部的40名患者中，对青蒿琥酯单用和青蒿琥酯/甲氟喹联用治疗的应答进行了评估。
柬埔寨患者中发生寄生虫清除的时间显著长于泰国患者(p < 0.001)。然而，体外试验表明，对青蒿琥酯的敏感度并没有降低。
作者总结说：“现在迫切需要一些防范措施，来控制这些寄生虫从柬埔寨西部传出的速度并避免威胁到消灭疟疾计划”。
在第二项研究中，荷兰内梅亨大学的Robert Sauerwein博士及其同事，对子孢子接种免疫法进行了测试。
有10名健康受试者接受了子孢子感染后的蚊虫叮咬（疫苗组），另外5名接受了未感染的蚊虫叮咬（对照组），每月一次，连续三个月。在这三个月的免疫期中，两组都服用氯喹进行预防。停用氯喹后一个月，所有受试者都接受了感染恶性疟原虫的蚊子的叮咬。
疫苗组的所有受试者获得完全保护，但是对照组的所有患者都发生了寄生虫血症。两组均无严重的不良事件。
虽然使用疫苗进行预防的策略并没有得到广泛应用，“但将来可以考虑使用疫苗对疟疾进行预防”，作者总结道。

http://www.medscape.com/viewarticle/706740

Artemisinin-Resistant Malaria Detected in Western Cambodia

NEW YORK (Reuters Health) Jul 29 - New research indicates that artemisinin resistance among Plasmodium falciparum isolates is common in western Cambodia and that in vitro testing may give false results.

Findings from another study indicate that inoculation of intact sporozoites can induce protection against malaria challenge. Both studies are reported in The New England Journal of Medicine for July 30.

Recent research suggests that artemisinin-based therapies are losing their efficacy against falciparum malaria on the Thai-Cambodian border, a site where antimalarial-drug resistance has been described in the past.

In the first study, Dr. Arjen M. Dondorp, from Mahidol University, Bangkok, and colleagues assessed the response to artesunate with or without mefloquine in 40 patients living in western Cambodia and 40 in northwestern Thailand.

The time to parasitic clearance was significantly longer in the Cambodian patients: 84 vs. 48 hours in Thai patients (p < 0.001). In vitro testing, however, did not show reduced sensitivity to artesunate.

\"Measures for containment are now urgently needed to limit the spread of these parasites from western Cambodia and to prevent a major threat to current plans for eliminating malaria,\" the authors conclude.

In the second study, Dr. Robert Sauerwein, from Radboud University, Nijmegen, the Netherlands, and colleagues examined sporozoite inoculation, via mosquito bite, as a means of inducing immunity against malaria.

Ten healthy subjects received bites from infected mosquitos (vaccine group) and 5 received bites from uninfected mosquitos (control group), once a month for 3 months. Chloroquine prophylaxis was given to both groups during this immunization phase. One month after stopping chloroquine, all of the subjects underwent malaria challenge with mosquitos infected with P. falciparum.

The subjects in the vaccine group were fully protected against malaria challenge, whereas all subjects in the control group developed parasitemia. No serious adverse events were seen in either group.

Although the described study protocol does not represent a vaccine strategy that can be widely implemented, \"the induction of sterile protection against a homologous malaria challenge suggests that the concept of a whole-parasite malaria vaccine warrants further consideration,\" the authors conclude.

N Engl J Med 2009;361:455-477.