More than a third of the children in the UK get head lice (pediculosis) in a year,1 and the prevalence of pediculosis increases in crowded conditions and with poorer hygiene.2 Increasing overcrowding of cities will result in an even greater prevalence.

A primary school child needs about 1.5 mg of iron per day3 and iron loss is about 0.6 mg/day.3 A louse can cause blood loss of 1 mg/day, and this could therefore tip this balance in favour of iron deficiency anaemia, especially in a child who is already depleted in iron due to a poor diet.

The effect …