Encouraging handwashing can slash the prevalence of worm infections in children, a study in Ethiopia has found. The six-month trial, published today in PLOS Medicine , found that regularly cleaning the hands with soap reduced new infections by intestinal parasites by 68 per cent. Weekly nail clipping reduced such infections by 49 per cent. The researchers also found that handwashing lowered children's rates of anaemia. The team of scientists split school-aged children into four treatment groups. One group received weekly nail clipping, one received soap and regular reminders to wash their hands, one received both treatments and a control group received neither intervention.