Louse Comb Versus Direct Visual Examination for the Diagnosis of Head Louse Infestations

Abstract

The techniques used for diagnosis of head louse (Pediculosis capitis) infestation are a source of controversy. Most epidemiologic and diagnostic studies have been done using direct visual examination. The main objective of this 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 used a screening stick and another team used a louse comb. Seventy-nine boys and 201 girls, 7-10 years old were examined. Examination with a louse comb found that 25.4% of the children were infested with both lice and nits, while another 31.3% had nits only. Boys were significantly less infested with lice and nits than girls (lice: 15.2 and 29.6%; nits: 21.5 and 35.4%, respectively). The infestation rate with lice and nits was significantly higher in children with long (68.9%) and medium-length (63.9%) hair than in children 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 examination. 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.

Prevalence of pediculosis capitis in children from a rural school in Yucatan, Mexico

“…Thereafter, the same investigator re-examined the participant's entire scalp by wet combing (using a commercial head-lice comb) -the most sensitive method for detecting head lice 5,12,13,18 . The hair was moistened and a commercial conditioner applied.…”

Pediculus capitis infestation according to sex and social factors in Argentina

“…This time was set based on Mumcuoglu et al, 6 who showed that the average time until detection of the first (mobile) louse by direct visual examination was 116 seconds. Based on the results obtained by Williams et al 14 special attention was put on the number and position of nits in relation to the scalp as indicators of parasitism intensity.…”

Head Lice

“…Studies have revealed that diagnosis of infestation by using a louse comb is quicker and more efficient. 22 Some experts have suggested using a lubricant (water, oil, or conditioner) to "slow down" the movement of lice and eliminate the possibility of static electricity. 23 The tiny eggs may be easier to spot, especially at the nape of the neck or behind the ears, within 1 cm of the scalp.…”