In the past the advice has been that dog & cat poo should not be composted because of the risk of the roundworm Toxocara canis and the risk of Toxoplasma from cat faeces.
While Toxocariasis in humans is relatively uncommon, with
an average of 10 cases occurring each year in England, it can be serious. Evidence of human infection by T. canis in London blood donors was found to be present in 2.6% of those sampled (Bignall, 1993).
T. canis was found in 6.3%
of soil samples from London parks and gardens (Gillespie et al., 1991) while another survey found soil samples from 66% of London parks (Lloyd S 1998).
Toxocara canis eggs from in grass, soil, or compost, may contaminate
the hands and then be ingested. Eggs which are swallowed can hatch into larvae in humans but will not develop into adult worms. The larvae will travel around the body – usually causing no problems but can settle in the retina where they may causing
damage or blindness. Toxocariasis usually affects children who are between one and four years old. However, cases have been reported in people of all ages. Younger children are particularly at risk because their play habits make them more likely to
come into contact with contaminated soil. Many young children also have a habit of eating soil.
The symptoms of toxocariasis can vary depending on where in the body the infection occurs. There are three main types:
1. Covert toxocariasis. This is the most common and mildest form of toxocariasis. Symptoms include abdominal pain, a cough and headache.
2. Visceral larva migrans. Visceral larva migrans develops when
large numbers of parasites spread through different organs of the body, such as the lungs, liver and heart. The symptoms include fever, abdominal pain and shortness of breath.
3. Ocular larva migrans. This is the least common
but potentially most serious type of toxocariasis. The condition can develop if the larvae move into the eyes.The main symptoms are disturbed vision and irritation of the eyes. Left untreated, ocular larva migrans can result in permanent vision loss, although
only one eye is usually affected. About 50 cases of toxocara involving eye damage are reported annually. www.threerivers.gov.uk
Toxocara are survivors and can cross the placental barrier
so that an infected bitch will have infected her puppies before they are born. The parasite can remain domant in the tissue of the bitch until she become pregant. However recent surveys of pet dogs, which we assume are regularly wormed, have shown that
only 1% of animals are passing eggs in the faeces. Higher figures have been obtained where samples have been taken from parks in towns but these samples are likly to include a number of stray and untreated animals (including foxes).
The eggs can survive
the cold or cool composting and contaminate the soil and plants on which the compost is used. It can then being transferred to the hands and be ingested by children, or by children and adults eating contaminated food.
may contain toxoplasmosis, which can cause fetal blindness, brain damage of unborn children and as consequence is a particular risk to pregnant women. The adult parasite involved is carried by cats, but the eggs shed
in the manure can infect humans, pigs, cows and other mammals. Diagnosis is difficult because the symptoms of toxoplasmosis are similar to those of a flu. Under normal conditions the sporulated oocysts can survive a year or more in the soil
or sand (cats like to deposit samples in sand pits). However hot composting at 60°C will reduce most pathogens to safe levels within an hour and will kill T. gondi
However cat waste is more difficult than dogs faeces to
deal with as it is likely to be buried in the garden rather than left sitting on the lawn or soil. However the faeces from cats who use a litter tray can be composted provided the correct cat litter and the right method are used
If you keep dogs
or cats which poo in the garden the risk of contamination already exists. Simple additional control measures can be used to ensure that composting dog faeces in a wormery does not add to the risk.
and nursing bitches are sources of infection they should be treated before and after whelping. Waste from these animals should not be composted
- All puppies and kittens should
be assumed to be infected with worms, and they should be treated routinely in accordance with veterinary advice.
- Treat adult dogs 3 -6 monthly to reduce the
- After worming wait 1 week before adding poo to your wormery.
wear gloves and wash your hands.
Do not use worm compost made from dog poo:
- On vegetables or soft fruit
- As mulch on flower beds were dogs have access or where children play.
Do not put cat faeces in a wormery
- Pregnant women should avoid contact with cat faeces.
- Garden vegetables should be washed thoroughly before eating because they may have been contaminated with cat faeces