Levamisole: a safe and economical weapon against pediculosis.
Twenty-eight patients with pediculosis capitis, defined as the presence of pruritus, living eggs, and/or lice in the hair, were enrolled in an uncontrolled open pilot study. The subjects were school-age girls (7-12 years old), apparently free of other diseases, and not treated for pediculosis for 4 weeks prior to this study. Family contacts were not treated for pediculosis. The mothers of the patients, who had given informed consent, were asked not to use any topical pediculocide on the girls during the drug trial. Other than the drug administered in the study, the subjects did not take any oral medicine, including cotrimoxazole and ivermectin, during the trial. Treatment consisted of 3.5 mg/kg once daily oral administration of levamisole for 10 successive days, which was given to the subjects in their school by health personnel. A 10-day course was chosen because the subjects lived in unhygienic and overcrowded conditions in a poor village where head lice infestation was hyperendemic. Therefore, two treatment courses spaced 10 days apart could not preclude new infestations from other affected persons and fomites and might have led to a false deduction of drug ineffectiveness. Substituting "N" for the grade of living nits and "L" for adult lice, three forms of response based on the meticulous examination of the entire scalp with the use of a lens with high magnification and a powerful light source were considered: (i) total responsiveness, defined as N2 = 0 and L2 = 0; (ii) partial responsiveness, defined as 0 not equal N2 < N1 and 0 not equal L2 < L1; and (iii) complete unresponsiveness, defined as N2 > or = N1 or L2 > or = L1. The detection of unhatched nits which were operculated and generally located within one-quarter of an inch of the scalp was used to indicate the presence of lice infestation and also to judge the clinical response. For those small nits whose opercula were difficult to see with a hand lens, a low power microscopic study was performed to determine whether the nits were unhatched or not. Of the 28 girls enrolled in the study, one patient refused to take the drug after 2 days of treatment. No adverse reactions were noted in any of the 28 subjects. On the 11th day, meticulous hair examination showed that 23 patients had responded to treatment (85%; 95% confidence interval (CI): 66-94%). Of these, 18 showed complete responsiveness (67%; 95% CI: 48-82%). More complete information is given in Table 1. Confidence intervals were calculated using the likelihood method. This study suggests that levamisole is effective against pediculosis with a dose of 3.5 mg/kg administered for 10 days.