This is the VOA Special English Health Report.
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| Schistosoma mansoni, one of three major kinds of worms that cause schistosomiasis |
Scientists think they are a step closer to a new drug to treat schistosomiasis. More than two hundred million people suffer from this parasitic worm disease. Most live in developing nations in tropical climates. About ten percent of victims become seriously disabled from internal bleeding, iron loss, organ damage or other effects.
A team in the United States found that chemical compounds known as oxadiazoles can target an enzyme needed for the survival of Schistosoma. This is the group of flatworms that cause schistosomiasis.
The scientists tested oxadiazoles on laboratory mice. They found that one compound killed the parasite at every level of development ��?from larva to adult. The study also showed that the compound was active against all three major species of Schistosoma worms that infect humans.
The National Institutes of Health supported the research. Scientists from Illinois State University and the Chemical Genomics Center at N.I.H. reported their findings in the journal Nature Medicine.
Biology professor David Williams led the research. He says the Schistosoma parasite needs oxygen to survive. Oxygen use produces oxygen-free radicals that can destroy an organism. The worm has a protective enzyme. But Professor Williams says the experimental drug disables this enzyme, causing the worm to self-destruct.
Since the nineteen eighties, doctors in more than seventy tropical nations have used one main drug to treat schistosomiasis. Public health experts worry that the worms will become resistant to this drug, praziquantel.
Each year, two hundred eighty thousand people die of schistosomiasis, also known as bilharzia or snail fever. The microscopic worms infect snails, which in turn lay infected eggs. Humans become infected when they enter fresh water where the snails live.
The worms dig through skin to enter the body. They move into blood vessels that supply the intestinal and urinary systems. Then, if worm eggs in human waste enter fresh water, more snails and people become infected.
More studies are needed on the experimental new drug. The scientists say the results in mice were better than all the targets set by the World Health Organization for new schistosomiasis compounds. They hope the drug will be ready for testing in humans in four to five years.
And that’s the VOA Special English Health Report, written by Jill Moss. Transcripts, MP3s and podcasts of our reports are at voaspecialenglish.com. I’m Steve Ember.
译文:
新药有望治疗血吸虫疾病
科学家认为现在生产治疗血吸虫疾病的药品越来越可能了。全球有近两亿人口患有血吸虫病。这些患者大部分居住于热带发展中国家。大约10%的患者由于内出血、体内缺铁、器质受损或者其它原因，而导致严重残疾。
美国的一个科学小组声称发现一种名为oxadiazoles的化合物可处理血吸虫赖以生存的酶。这个小组致力于研究扁形虫，扁形虫可导致住血吸虫病。
科学家在实验鼠上为oxadiazoles化合物作测试。他们发这种化合物可以杀死从幼虫到成体不同阶段的寄生虫。试验表明这种化合物在对付所有可感染人类的三种扁形虫卓有成效。
美国国家卫生研究所为这项研究提供支持。来自伊利诺斯州立大学的教授和国家卫生研究所的化学基因研究中心的研究员在自然杂志上发表了他们的研究发现。
生物学教授大卫·威廉姆斯领导着这项科研。他说血吸虫寄生虫需要氧气得以生存。寄生虫利用氧气，产生一种氧自由基以破坏人的有机体。同时寄生虫有一种自我保护的酶，试验的药品可以破坏这种酶，使寄生虫自我灭亡。
从19世纪80年代， 70多个的热带国家的医生一直就用吡喹酮这种药来治疗血吸虫病，公共健康专家担忧血吸虫对这一药品已有了抗体。
每年有28万人死于血吸虫病。血吸虫能感染蜗牛，此时的蜗牛产下的卵也被感染。一旦人进入蜗牛生活的水中，即有可能被感染。
血吸虫从皮肤进入体内。它们进入肠和泌尿系统的血管。当血吸虫卵随着人体的排泄物到了水中，那么更多的蜗牛和人就被感染。
试验的药品当然还需要更多的研究。科学家认为这一药品在试验用鼠上的效果好于其它世界卫生组织选取的试验品。他们希望这一药品能在四到五年的时间内在人体上做试验。