60秒科学:森林的过度砍伐导致痢疾在巴西肆掠

A 4 percent decrease in forest was associated with a nearly 50 percent rise in malaria¹ cases in western Brazil.

You know saving the rainforest is good for biodiversity. But it may also be a boon² to human health. That's because less clear-cutting may mean less malaria, according to a paper out this week in the journal Emerging Infectious Diseases.

Researchers looked at stats for 2006 from 54 health districts in western Brazil. The sites had more than 15,000 cases of malaria. The investigators³ compared those cases to deforestation in the same health districts over the previous 10 years. They found that a loss of just four percent of forest cover was associated with nearly 50 percent more malaria cases. And malaria risk was highest five to 10 years after the jungle was cleared.

Not all mosquitoes carry malaria. But the human-loving species Anopheles darlingi does, and previous studies have shown that it thrives in disturbed areas. In fact, you're over 200 times more likely to find one of them biting you in a clearing than you are deep in the jungle, where other more benign⁴ species compete with them for blood.

So how much clear-cutting is too much? We don't know yet—but an intact swath of rainforest appears to provide free public health services.
 

1 malaria   

n.疟疾

参考例句：

• He had frequent attacks of malaria.他常患疟疾。
• Malaria is a kind of serious malady.疟疾是一种严重的疾病。

2 boon   

n.恩赐，恩物，恩惠

参考例句：

• A car is a real boon when you live in the country.在郊外居住，有辆汽车确实极为方便。
• These machines have proved a real boon to disabled people.事实证明这些机器让残疾人受益匪浅。

3 investigators   

n.调查者，审查者( investigator的名词复数 )

参考例句：

• This memo could be the smoking gun that investigators have been looking for. 这份备忘录可能是调查人员一直在寻找的证据。
• The team consisted of six investigators and two secretaries. 这个团队由六个调查人员和两个秘书组成。 来自《简明英汉词典》

4 benign   

adj.善良的，慈祥的；良性的，无危险的

参考例句：

• The benign weather brought North America a bumper crop.温和的气候给北美带来大丰收。
• Martha is a benign old lady.玛莎是个仁慈的老妇人。