They mature in 10 days and live about 3 weeks or more. Head lice are contagious. Close person-to-person contact or sharing personal belongings, such as hats, puts people at risk of catching head lice. Head lice cannot fly or jump. Dogs, cats, and other pets do not play a role in the spread of human lice. Head lice are not known to transmit diseases and are not considered dangerous. Children ages 3-11 and their families get head lice most often