一种由吸血昆虫引发的致命疾病----查加斯病 (Chagas disease)----正在全球逐渐蔓延，因感染者在患病初期出现与患艾滋病的症状相似----很难被察觉且具有很多年的潜伏期，所以有关专家把它称为美洲国家面临的“新型艾滋病”威胁。
这种疾病一般通过锥猎蝽的叮咬、将被称为克氏锥虫的寄生虫输入受害者血液中进行传播，还可能在妊娠和生育期间由母亲传播给孩子。
在被感染后，患者一般经历两个阶段----急性期和重症期。急性期之后，病情表面上会趋于缓和，再经过数年后，患者才会进入重症阶段，出现便秘、腹痛以及消化系统疾病等病症。
一般来说，贫困地区的居民发病率较高，若患者发现得早，通过3个月的大剂量药物治疗，病情可能不会恶化，但由于该疾病潜伏期十分漫长，且发现后治疗费用高昂，所以很多患者不得不放弃治疗。
查加斯病最初只是在拉丁美洲爆发，后来因为旅行和移民的原因，逐渐蔓延到美国境内。
目前全球感染者据估计有1000万人，多数患者来自玻利维亚、墨西哥、哥伦比亚以及中美洲的一些国家，而美国人被感染的人数接近3万。
鉴于这种疾病危害大、感染人数多以及难以预防的特点，美国疾病预防控制中心已经将其列为五大被忽视的寄生虫感染疾病之一。
(网易新闻中心)
Chagas disease, which is
caused by parasites transmitted to humans by a tiny insect called the “kissing
bug”, is “the New HIV/AIDS of the Americas”, according to a leading expert in
tropical diseases.
In an editorial in the PloS Neglected Tropical
Diseases journal, Dr. Peter Hotez warns of the serious consequences of the
disease which is already widespread amongst the poor and indigenous groups in
Latin America and parts of the United States, specifically Texas and the Gulf
coast.
The disease — named after Carlos Chagas, a Brazilian doctor who
first discovered it in the early 20th century — is caused by a parasite known
as a trypanosome. The parasite is carried by the “kissing bug” which has been
described as a cockroach with a long proboscis (snout) that allows it to feed
on blood.
But the parasite itself is transmitted through the bug’s feces.
When the bug bites someone it also defecates on them and the parasite enters
the body, Hotez explained.
The kissing bug is found throughout the poorer regions of the
Americas in Brazil, Bolivia, the Amazon regions, Central America, Mexico and
southern Texas.
Once infected, it can take up to 10 to 15 years for the damage
from the disease to manifest itself.
Reports suggest there are some 10 million cases in the Western
hemisphere, predominantly in Latin America.
About 30 per cent of people with Chagas will develop heart
disease — about 3 million of the 10 million infected with trypanosomes in the
Western hemisphere.
Of those 3 million the majority will ultimately die from the
disease, Hotez said. Some estimates suggest 20,000 die annually from the
disease, he added.
The disease can cause fatal heart disease — including
cardiomyopathy and arrhythmias — as well as damage to the intestines and
esophagus.
Treatment for Chagas , officially known as American
trypanosomiasis, involves taking the drug Benznidazole for three months.
But the treatment often doesn’t provide any relief and only
works if the disease is caught early.
If global action isn’t taken, Hotez fears conditions may be ripe
for what he describes as a “perfect storm” for infection and transmission
amongst the poor.
Hotez and his co-authors believe there are striking similarities
between the people living with Chagas and those living with HIV/AIDS,
especially those who contracted the disease in the first 20 years of the
epidemic.
Both diseases are chronic and can remain undetected for years,
he explains. Transmission can occur through blood transfusions or organ
transplants and as well as through mother-to-child during pregnancy just like
HIV/AIDS.
The American Red Cross universally tests for Chagas, said Hotez.
A spokesman for Canada Blood Services said that it only screens for the disease
based on a donor’s ancestry, place of birth or recent travels and if the
potential donor has been to a place where Chagas is common.
Both diseases also share a stigma that prevents care. In the
case of HIV/AIDS sexual orientation had been a barrier to care. With Chagas,
immigration status may prove to be a deterrent to care and prevention, said
Hotez, dean of the National School of Tropical Medicine at Baylor
College of Medicine in
Houston.
“It occurred to me one day how similar it is now with Chagas to
the early years of the AIDS epidemic when they didn’t have good drugs or an
understanding of the disease,” said Hotez.
The U.S. Centre for Disease Control estimates there are 300,000
cases in the U.S. But Hotez believes it’s closer to one million cases in the
U.S. overall.
There are also cases in Canada, but a much smaller number of
people have been exposed to the disease. A 2010 study in Journal Actatropica
reports that 3.5 per cent of the 156,960 immigrants to Canada from Latin
America in 2006 were infected with Chagas.
“It’s a forgotten disease among forgotten people,” Hotez said.
“Can you imagine having 300,000 people in the suburbs with a serious case of
heart disease caused by a bug? We wouldn’t tolerate it as a society, but
because it’s happening to an indigenous people we’re silent.”
Hotez and his lab are working on developing a prototype vaccine
that would be given after exposure to Chagas, like a rabies vaccine.
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