By Cara Liu
CBS 5

PHOENIX (April 29, 2008) -- More than a half-dozen people have been bitten by rattlesnakes in the last two weeks, and doctors are now warning that the venom is becoming more poisonous...

...Valley doctors are starting to see more patients becoming critically ill after rattlesnake bites, compared to just a few years ago.

"These patients commonly have very low blood pressure. Many times they're lethargic or unconscious," said Dr. Steve Curry of Banner Poison Control.

Similar trends are appearing in southern Arizona, Colorado and southern California.

"The reason for this isn't clear to us," Curry said. "Snake venom can't just change across the country all at once."

Whatever the reason, Curry says rattlesnake bites are becoming more dangerous. That means it's even more important for someone who's bitten to get medical help right away.

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