In theory, they could feed on cattle, goats, sheep, or donkeys rather than people, says Vernick, in which case they wouldn't be important for human malaria transmission.

Vernick说，理论上讲，它们会叮牛、山羊、绵羊或者驴子，而不是人类。要是那样的话它们就对人类疟疾的传播影响很小。

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"They didn't just try to make drivers safer or try to criminalize (drunken) driving -- that alone wouldn't have worked, " Vernick said.

CNN: Kids and guns: 'These are not isolated tragedies'

Because people studied why car accidents happened in the 1960s, for instance, public health advocates knew how to improve injury rates from such crashes, Vernick said.

CNN: Kids and guns: 'These are not isolated tragedies'

The research is a good and descriptive small-scale study, said Jon Vernick, an associate professor and co-director of the Johns Hopkins Center for Gun Policy and Research, but it also is a good reminder that public health experts need to do more of this kind of research.

CNN: Kids and guns: 'These are not isolated tragedies'