消灭疟疾任重道远

　　A new vaccine is one step towards a distant goal

　　一种新疫苗让人类离消灭疟疾更近了一步

　　MAN has vanquished only one disease, smallpox. In 2007 Bill Gates set out to eradicate another, malaria. The World Health Organisation (WHO) was soon rallying its troops to the cause and a flood of money followed. $612m went to research in 2009 alone. This week the Bill & Melinda Gates Foundation trumpeted another announcement: results from a phase III trial (the more extensive process of testing drugs in people) of a malaria vaccine called RTS,S. This is the world’s most advanced vaccine for malaria and the results, published in the New England Journal of Medicine, were encouraging.

　　到目前为止人类只消灭了天花这一种疾病。2007年，比尔?盖茨宣布开始着手消灭另一种疾病即疟疾。世界卫生组织迅速召集队伍致力于这项事业，并在随后投入大量资金，2009年仅在研究上就投入了6.12亿美元。本周，“比尔和梅琳达?盖茨基金会”发表了另一个声明，内容是世界上对抗疟疾最先进的疫苗RTS，S的第三试验阶段（在人群中广泛使用药物并测量反应）的结果，发表于《新英格兰医学杂志》上的结果振奋人心。

　　It is an important step in combating a disease that still kills more than 700,000 people a year and debilitates millions more. But it is also a reminder of how much work remains to be done.

　　每年因疟疾致死的人有700000人，致残的有 数百万人，这个试验结果是战胜这一疾病的重大进步。但是它也提醒人们还有多少任务尚未完成。

　　Mr Gates is only malaria’s latest adversary. The parasite has plagued man for millennia. Chinese texts from 2700BC describe plants to treat its fevers. More recently, in 1955, the WHO embarked on its first malaria-eradication effort. But transmission rates in Africa seemed intractable. After 14 years the WHO gave up. The last time the world tried to eliminate malaria, some scientists lament, the world eliminated malariologists.

　　疟疾祸害人类千年，盖茨先生最近一个反抗它的对手。公元前2700年中国的文字资料就记载着一些植物能治疗由疟疾引起的发烧的。再往离现在近的时间看，世界卫生组织在1955年展开首次消灭疟疾的行动。但是在非洲，遏制疟疾的传播率似乎非常棘手。14年之后，世卫放弃了。有些科学家慨叹，上一次世界本来试图消灭疟疾，结果被消灭的是疟疾学家。

　　The new wave of enthusiasm came with the founding of the Roll Back Malaria Partnership in 1998 (to co-ordinate planning), the PATH Malaria Vaccine Initiative in 1999 (with money from the Gates Foundation) and the United Nations’ Global Fund to Fight AIDS, Tuberculosis and Malaria in 2002. This culminated in Mr Gates’s call to arms four years ago and has helped to lower the number of malaria deaths by 20% over the past decade.

　　随着1998年“遏制疟疾伙伴关系”（共同测绘）、1999年“疟疾疫苗开发计划”（资金来自盖茨基金会）和2002年联合国全球治疗艾滋病肺结核和疟疾基金的建立，对抗疟疾的新一轮热潮出现了。四年后盖茨振臂一呼，在十年里疟疾死亡率降低了20%，推动抗疟疾的热潮达到顶峰。

　　More progress will be difficult. The existing tools of insecticide-treated bed nets and treatment drugs require careful co-ordination and good health systems. Eliminating malaria in a stable country is dramatically easier than doing so in a turbulent one. Worryingly, these tools may become less effective. Parasites in South-East Asia, for example, seem to be developing resistance to artemisinin-based treatments. To achieve eradication—or anything close to it—new weapons are needed.

　　要想获得更多进展非常困难。现有的带有杀虫剂蚊帐和药物治疗要求配合细致和良好的医疗系统。在一个政局稳定的国家消灭疟疾比在政局动荡的国家更容易。比如，东南亚的寄生虫似乎对基于青蒿素的治疗起了抗药性。要想消灭疟疾——或是向这个目标再迈进一大步—就得发展新武器。

　　RTS,S, developed by GlaxoSmithKline (GSK), a British pharmaceutical company, will help. The vaccine tries to stop one type of malaria parasite, Plasmodium falciparum, before it has a chance to wreak havoc. A mosquito’s bite delivers malaria to the body. Travelling swiftly to the liver, the parasites hide, mature and multiply before staging a grand second act in the bloodstream, where they invade red blood cells, multiply again, and invade more cells. RTS,S combines a circumsporozoite protein, which exists on the parasite’s surface, with a protein from a hepatitis B vaccine. Together, these trigger an immune response which can fight off invading parasites before the second act.

　　这个新武器就是由英国制药公司葛兰素史克公司(GlaxoSmithKline研制的RTS，S。该疫苗能停止疟疾寄生虫恶性疟原虫的活性，使它不能为非作歹。蚊子叮一口就会把疟疾传到人身上。它传播敏捷，在寄主身上隐藏起来、成熟、繁殖，然后在血液里进行第二个大的行动，入侵红细胞后再次繁殖，接着侵占更多细胞。RTS,S把存在于寄生虫表面的环子孢子蛋白和肝炎B型疫苗里的一种蛋白结合在一起。它们共同作用引发一种免疫反应，在第二次活动前就击退入侵的寄生虫。

　　GSK tested the vaccine in 6,000 infants across sub-Saharan Africa. It reduced the risk of clinical malaria by 56% and severe malaria by 47%. This efficacy was “on the positive side of what we were expecting,” says Christian Loucq of the PATH Malaria Vaccine Initiative, GSK’s partner on RTS,S.

　　葛兰素史克公司在撒哈拉以南非洲的6000名婴儿身上测试了这种疫苗。患临床疟疾的风险减少了56%，患严重疟疾的风险减少了47%。葛兰素史克公司在研制RTS.S的搭档“疟疾疫苗开发计划”的Christian Loucq说这种效力“是我们曾期待的积极一面”。

　　However, more is to come. The trial examined children aged 5-17 months. Results for younger babies will follow. Still uncertain is how long the vaccine’s protection lasts. The first year that the vaccine might be used would be 2015, and that is if everything goes as planned. Even then, it is unclear how RTS,S might be deployed. Its price is uncertain and its power limited. “We realise that RTS,S is not the ultimate malaria vaccine,” says David Brandling-Bennett of the Gates Foundation. “But it will have some role. The challenge is figuring out what that role is.”

　　然而，更多的试验紧随其后。上面提到的试验测试对象是5-17个月大的婴儿。随后会出炉年龄更小婴儿的结果。这种疫苗的保护能持续多久还不清楚。疫苗投入使用可能会从2015年开始，前提是如果一切按计划进行的话。即使到那时候，还不清楚RTS.S会怎样投放。价格不定，效力也是有限的。“我们认识到RTS.S并非是最好的疟疾疫苗，”盖茨基金会的大卫?布兰丁-博内特这样说，“但是它会起到一些作用。我们的挑战是研究出这种作用是什么。”

　　Researchers are already working on the next generation of vaccines. GSK hopes to induce a stronger immune response by combining RTS,S with a vaccine from Crucell, another drug firm. Scientists are also keen to develop vaccines that target different kinds of malaria parasites and in different ways—for example, in mosquitoes’ guts. All of this work requires further investment at a time when global health programmes must compete fiercely for cash. Mr Gates has helped to spur progress. Sustaining it is the next challenge.

　　研究者已经开始从事下一代疫苗的开发。葛兰素史克公司希望使用RTS，S和另一家制药公司Crucell的一种疫苗的结合体来引起更强烈的免疫反应。科学家也努力研制针对不同种类疟疾寄生虫和不同感染途径——比如，在蚊子的内脏里——的疫苗。这些工作都需要继续投入资金，而现在正是全球医疗项目必须为资金激烈竞争的时候。盖茨先生已经为推动研究进步做出贡献。如何保持这种势头是下一个挑战。