Louse comb versus direct visual examination for the diagnosis of head louse infestations

The techniques used for diagnosis of head louse (Pediculosis capitis) infes tation are a source of controversy. Most epidemiologic and diagnostic studi es have been done using direct visual examination, The main objective of th is study is to compare the efficacy of direct visual examination versus the louse comb method. The hair of each child was examined twice; one team use d a screening stick and another team used a louse comb. Seventy-nine boys a nd 201 girls, 7-10 years old were examined, Examination with a louse comb f ound that 25.4% of the children were infested with both lice and nits, whil e another 31.3% had nits only. Boys were significantly less infested with l ice and nits than girls (lice: 15.2 and 29.6%; nits: 21.5 and 35.4%, respec tively), The infestation rate with lice and nits was significantly higher i n children with long (68.9%) and medium-length (63.9%) hair than in childre n with short hair (44.0%) (p < 0.01), Direct visual examination found that 5.7% of the children were infested with both lice and nits, and another 49. 0% with nits only. The average time until detection of the first louse was 57.0 seconds with the comb as compared to 116.4 seconds by direct visual ex amination. Diagnosis of louse infestation using a louse comb is four times more efficient than direct visual examination and twice as fast. The direct visual examination technique underestimates active infestation and detects past, nonactive infestations.