Much like Legionaires Disease, Hantavirus isn't something you hear a lot about - until there is an outbreak.  The recent cases that have popped up in Yosemite National Park have brought the rodent-borne disease back into the limelight;  They might also help researchers with clues to how the virus spreads and what can be done to help humans fend off the risks.

Authorities are looking into several factors that could have contributed to the outbreak, but recent trapping indicates that the park's deer mouse population is larger this year, said Dr. Vicki Kramer, head of the California Department of Public Health's vector-borne disease section. Deer mice are the primary carriers of hantavirus in the U.S.

Humans  might also be to blame for contributing to factors that help harbor a larger mice population.

The development of Curry Village [a tent city at Yosemite] was also something to consider, she said. The popular campground offers more food for the mice, as well as protection -- their natural predators are more likely to be scared off by such a large human presence.

Whatever the cause, experts warn people to be aware of the risks and to learn what they can about Hantavirus.