Dog waste is classed as 'offensive waste' due to its bacterial content.
All faeces contains bacteria that can cause stomach upsets if ingested, however the greatest risk to public health from dog faeces is Toxocariasis.
Toxocariasis is an infection caused by Roundworm larvae spread by unwashed vegetables and dog faeces. Young children are at particular risk of infection due to their weaker immune systems and because they are more prone to ingest the eggs.
Each female Roundworm can lay up to 700 eggs a day. These are passed out when the dog poops and can survive for up to three years in soil. After two to three weeks of warm weather the eggs develop into an embryo state, containing larvae. This is when they can infect dogs and people. The larvae travel through the human body as they would in a dogs, but a human body treats them as foreign material which causes a reaction and tissue damage.
There are two types of Toxocariasis: Visceral Larva Migrans (V.L.M.) and Ocular Larva Migrans (O.L.M.).
In V.L.M., the larvae reach the liver, causing inflammation and symptoms such as abdominal pain and Pyrexia (raised body temperature; fever). Most people recover spontaneously.
O.L.M. occurs when a migrating larvae reaches the eye. It causes a Granuloma to form on the retina, causing significant visual impairment and in severe cases blindness.
On average there are 12 new cases of O.L.M. diagnosed each year in the U.K. The majority of these are children.