Head lice resistance: Itching that just won't stop

OBJECTIVE: To evaluate the reports of resistance and cross-resistance to pediculicides in the head louse (Pediculus capitis), as well as the mechanisms involved. DATA SOURCES: Literature identified through a MEDLINE search (1996-April 2000) and through other secondary literature databases and/or bibliographies of pertinent articles. DATA SYNTHESIS: Head lice infestation is a common, worldwide problem. The widespread use of insecticide treatments together with inadequate treatment methods has led to a concern regarding the potential development of resistant head lice. This literature review examines the reports of resistance of the head louse as well as the purported mechanisms involved. CONCLUSIONS: Current research suggests that head lice resistance exists, but little is known regarding the actual incidence of this resistance or whether this incidence is increasing. More research is needed to assess the status of this problem. Proposed mechanisms for head lice resistance include knock-down resistance, glutathione S-transferase-based resistance, and mono-oxygenase-based resistance.