Scanning electron microscopy of adult head lice (Pediculus humanus capitis) with focus on clinical implications

BACKGROUND: The incidence of head lice infestations in North America is escalating with an estimated 12 million cases of head lice per year despite the existence of insecticidal therapies. OBJECTIVE: To evaluate certain characteristics of the human head louse, including their chitinous structure, nymphal developmental stages, legs with claw adaptations, antennae with sensory perceptions, and spiracles by which oxygen exchange occurs, for assessment of possible means to control the spread and growth of this insect. METHODS: Scanning electron-microscopic examination of head lice was performed. RESULTS: Newer treatments of head lice must acknowledge defense mechanisms that are based on anatomic structure and physiologic characteristics, details of louse transmission, and the insects' ability to 'resurrect' after sham death. CONCLUSIONS: An understanding of lice entomology is essential in the pursuit of novel means to control the lice epidemic.