Two trials of 0.5% ivermectin lotion for the treatment of head lice, each in eight different centres in the USA, have been reported together (N Engl J Med 2012;367:1687–93; see also editorial, ibid:1750–2). A total of 765 patients (mostly children aged 6 months or older but a few adults, mean age 8 years) with head lice were randomised to a single application of 0.5% ivermectin lotion (rinsed off with water after 10 min) or placebo (vehicle). The rates of freedom from head lice (ivermectin vs placebo) on days 2, 8, and 15 were 94.9% vs 31.3%, 85.2% vs 20.8%, and 73.8% vs 17.6%. Adverse events, mostly pruritus, excoriation, and erythema, occurred in <1% of the ivermectin group and were more common in the control group. Ivermectin lotion was more effective than placebo. The writers of the editorial insist that ivermectin should be the last-choice treatment for head lice, after permethrin or pyrethrin, malathion, dimethacone or other topical agents, and wet combing.

Probably half of the world's population are at risk of contracting dengue and the more severe forms of the disease tend to occur in children. Vaccine …