Intestinal worms


WHO’s strategy

The strategy for control of soil-transmitted helminth infections is to prevent and control morbidity through the periodic treatment of at-risk population living in endemic areas. People at risk are:

  • preschool-aged children;
  • school-aged children;
  • women of childbearing age (including pregnant women in the second and third trimesters and breastfeeding women).

WHO recommends periodic treatment with anthelminthic (deworming) medicines, without previous individual diagnosis to all at-risk people living in endemic areas. Treatment should be given once a year when the prevalence of soil-transmitted helminth infections in the community is over 20%, and twice a year when the prevalence of soil-transmitted helminth infections in the community exceeds 50%. This intervention reduces morbidity by reducing the worm burden. In addition:

  • education on health and hygiene reduces transmission and reinfection by encouraging healthy behaviours;
  • provision of adequate sanitation is also important but not always possible in resource-constrained settings.

Periodic deworming can be easily integrated with child health days or vitamin A supplementation programmes for preschool-aged children, or integrated with school-based health programmes.

Schools provide an important entry point for deworming activities, as they provide easy access to health and hygiene education components, such as the promotion of hand washing and improved sanitation.

In 2011, over 300 million preschool-aged and school-aged children were treated with anthelminthic medicines in endemic countries, corresponding to 30% of the children at risk.


The aim of periodic administration of anthelminthics is to control morbidity from soil-transmitted helminthiases by reducing and maintaining low the intensity of infection.

Access to anthelminthic medicines

Donations of anthelminthic medicines are available through WHO to ministries of health in all endemic countries for the treatment of all children of school age.

Global target

The global target is to eliminate morbidity due to from soil-transmitted helminthiases in children by 2020. This will be obtained by regularly treating at least 75% of the children in endemic areas (estimated total number 873 million).

Accelerating work to overcome the global impact of neglected tropical diseases: a roadmap for implementation.

This publication reports the global target that was defined in the Strategic plan for the control of STH 2012–2020