Roundworms are a type of parasitic worm.
They are most common in places without modern sanitation.
According to the World Health Organisation (WHO), about 10 per cent of the developing world is infected with intestinal worms.
Children often become infected when they put their hands in their mouths after playing in contaminated soil, the WHO says.
Online site Healthline says the infection usually causes no symptoms, but a high number of roundworms (heavier infestations) can lead to problems in the lungs or intestines.
Healthline says people with ascariasis often have no symptoms but symptoms become more noticeable when the roundworm infestation grows.
