New Delhi: At least 40 percent of diarrhoea cases among schoolchildren across developing countries, including India, result from transmission in schools rather than home, the UN Children's Fund (Unicef) said today, on the eve of World Health Day. "One study revealed that more than 40 percent of diarrhoea cases in schoolchildren result from transmission in schools rather than homes. Damage to children's mental and physical health and development is due to diseases such as diarrhoea," the UN agency said. It said in a group of surveyed developing countries, nearly half of all primary schools in the developing countries do not have adequate water facilities and nearly two-thirds lack adequate sanitation. Even where facilities exist, these are often in poor condition. "Each year, children lose 272 million school days due to diarrhoea, and an estimated one in three school-aged children in the developing world are infested with intestinal worms," Unicef said in a report released today. Worms affect an estimated 400 million school-aged children in the developing world, including in India. Chronic hookworm infestations are associated with reduced physical growth and impaired intellectual development, and children enduring intense infestations with whip worm, miss twice as many school days as their infestation-free peers. "The average IQ loss per worm infestation is 3.75 points, representing 633 million IQ points lost for the people who live in the world's low-income countries," the report said. Girls who have reached puberty and female school staff who are menstruating need gender-related privacy. If no privacy is provided, students may not use the facilities at schools, resulting in absenteeism rates that can reach 10-20 percent of school time, the report added. It also emphasized that education is key to bettering health standards. "Women who have been to school are less likely to die during childbirth; each additional year of education is estimated to prevent two maternal deaths for every 1,000 women. Research also shows that for every 10 per cent increase in female literacy, a country's economy can grow by 0.3 percent."