Overdiagnosis and consequent mismanagement of head louse infestations in North America

Background. Lay personnel and many health care workers in the United States believe that head louse infestations caused by Pediculus capitis are excee dingly transmissible and that infested children readily infest others. Scho olchildren therefore frequently become ostracized and remain so until no si gns of their presumed infestations are evident. Repeated applications of pe diculicidal product and chronic school absenteeism frequently result. Methods. To determine how frequently louse-related exclusions from schools and applications of pediculicidal therapeutic regimens might be inappropria te, we invited health care providers as well as nonspecialized personnel to submit specimens to us that were associated with a diagnosis of pediculias is, Each submission was then characterized microscopically. Results, Health care professionals as well as nonspecialists frequently ove rdiagnose pediculiasis capitis and generally fail to distinguish active fro m extinct infestations. Noninfested children thereby become quarantined at least as often as infested children. Traditional anti-louse formulations ar e overapplied as frequently as are "alternative" formulations. Pediculicida l treatments are more frequently applied to noninfested children than to ch ildren who bear active infestations. Conclusions. Pediculicidal treatments should be applied solely after living nymphal or adult lice or apparently viable eggs have been observed. Becaus e health care providers as well as lay personnel generally misdiagnose pedi culiasis, and because few symptoms and no direct infectious processes are k nown to result, we suggest that the practice of excluding presumably infest ed children from school may be more burdensome than the infestations themse lves.