In low and middle income countries, about 1.2 billion people are infected with roundworm (Ascaris lumbricoides), and more than 700 million are infected with hookworm (Necator americanus or Ancylostoma duodenale) or whipworm (Trichuris trichiura).1 Infection with intestinal nematodes is linked with poverty because of its association with unsafe disposal of faeces, in which the infective stages develop.

Infection can occur in all age groups but is most common in school age children. Though infection can be fatal,2 the major burden of disease is due to its insidious effects on physical and cognitive development during childhood.3 Anaemia, for example, is commonly associated with infection and can impair cognitive ability.4 In areas of high prevalence of infection in East Africa, 15-25% of anaemia in schoolchildren is due to hookworm infection.5

In this week's BMJ, a systematic …