Phthiriasis palpebrarum is an infestation of the eyelashes caused by the louse Pthirus pubis (Linnaeus, 1758). We report a case of phthiriasis palpebrarum in a 6-year-old girl, which was initially misdiagnosed as allergic blepharoconjunctivitis. Parasites and their nits were found adhering to the eyelashes and eyelids of her right eye as well as scalp hairs. No abnormality was found in the left eye. The histopathology exam revealed the presence of adults and eggs of Pthirus pubis. We mechanically removed all the eyelashes of the right eye at their base, with lice and nits. The scalp was shaved and washed with phenothrin shampoo. No recurrence was found during 3 months of follow-up. Removal of the eyelashes, cutting of scalp hairs, and phenothrin shampoo may be effective in treating phthiriasis palpebrarum. In cases of blepharoconjunctivitis, eyelids and eyelashes should be carefully examined by slit lamp to avoid misdiagnosis.
Ivermectin and doxycycline have been found to be independently effective in killing body lice. In this study, 450 body lice were artificially fed on a Parafilm™ membrane with human blood associated with antibiotics (doxycycline, erythromycin, rifampicin and azithromycin) alone and in combination with ivermectin. Fluorescence in situ hybridisation and spectral deconvolution were performed to evaluate bacterial transcriptional activity following antibiotic intake by the lice. In the first series, a lethal effect of antibiotics on lice was observed compared with the control group at 18 days (log-rank test, P≤10(-3)), with a significant difference between groups in the production of nits (P=0.019, Kruskal-Wallis test). A high lethal effect of ivermectin alone (50ng/mL) was observed compared with the control group (log-rank test, P≤10(-3)). Fluorescence of bacteriocytes in lice treated with 20μg/mL doxycycline was lower than in untreated lice (P<0.0001, Kruskal-Wallis test). In the second series with antibiotic-ivermectin combinations, a synergistic lethal effect on treated lice (log-rank test, P<10(-6)) was observed compared with the control group at 18 days, associated with a significant decrease in the production of nits (P≤0.001, Kruskal-Wallis test). Additionally, survival of lice in the combination treatment groups compared with ivermectin alone was significant (log-rank test, P=0.0008). These data demonstrate that the synergistic effect of combinations of antibiotics and ivermectin could be used to achieve complete eradication of lice and to avoid selection of a resistant louse population.