This might make you want to wash your hands. One in ten of us has at some point swallowed eggs from Toxocara – a roundworm carried by dogs and cats that causes the commonest parasitic infection in industrialised countries. Children are most at risk because the parasite’s eggs find their way into humans on unwashed hands and foods after lying dormant in soil fouled by dog poo. Around one in four sandpits – irresistible to pets too – is contaminated. Mostly, the parasite dies before it can inflict harm. But it can also seriously damage our sight if it reaches the eyes, where it wreaks havoc on the retina by causing it to peel-off or fold (top left and right), or by spinning opaque veils across the clear gel that maintains the shape of the eye-ball (bottom). Although laser surgery and vitrectomy offer effective treatments, prevention through good hygiene is better than cure.
Written by Tristan Farrow
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.