Estimation of Ascaris infection risks in children under 15 from the consumption of wastewater-irrigated carrots

Ascaris lumbricoides, the large human roundworm, infects ∼1,200 million people, with children under the age of 15 being particularly at risk. Monte Carlo quantitative microbial risk analyses were undertaken to estimate median Ascaris infection risks in children under 15 from eating raw carrots irrigated with wastewater. For a tolerable additional disease burden of 10⁻⁵ DALY (disability-adjusted life year) loss per person per year (pppy), the tolerable Ascaris infection risk is ∼10⁻³ pppy, which can be achieved in hyperendemic areas by a 4-log unit Ascaris reduction. This reduction can be easily achieved by wastewater treatment in a 1-day anaerobic pond and 5-day facultative pond (2 log units) and peeling prior to consumption (2 log units).