Caylee Kapa of the Detroit suburb Madison Heights said she picked up the 9-inch-long pit viper to prevent her 10-year-old brother from stomping on it and it bit her on her right index finger, the Detroit Free Press reported Thursday.
The incident occurred Tuesday at Stony Creek Metropark in neighboring Macomb County.
Caylee's mother, Cyndi McLauchlan, said the bite caused her daughter's hand and wrist to swell up, prompting doctors to administer anti-venin.
The small snake, an eastern massasauga rattlesnake, is Michigan's only venomous snake. It's rarely seen but is found throughout the state's Lower Peninsula, the Michigan Department of Natural Resources said.
It is illegal to kill the snake because it is considered a species of special concern. It is a shy, non-aggressive reptile.