The human infection (toxocariasis) is rare and is caused by roundworm parasites. It usually affects young children.This is because children are more likely to come into contact with contaminated soil when they play and put their hands in their mouths. However, cases have been reported in people of all ages. Toxocariasis may occur if mature Toxocara (roundworm) eggs are swallowed, however, it is very rare for anyone to become ill as a result. About 1-2% of healthy adults in the UK already possess Toxocara antibodies which means that they have been exposed to Toxocara eggs or larvae with no ill effects.
On the rare occasions when human disease does occur, it usually causes only mild symptoms. In exceptional cases it can cause damage to the eye in young children this is called ocular toxocariasis. The chances of developing toxocariasis are low. It is estimated that there are only about two new cases of disease due to Toxocara infection per million of the population each year. A study on toxocariasis in school children in Ireland found that of 121,156 pupils surveyed eleven ocular toxocariasis cases were identified. The estimated number of definite cases of ocular toxocariasis was 6.6 cases per 100,000 persons. When ophthalmologists on Merseyside whose hospital practices served a population of about 200,000 children were asked about cases of ocular toxocariasis they could only recall 3 cases of ocular toxocariasis between them in the previous 20 years.
Advice to Pet Owners
- Parents and children should be aware of the dangers associated with puppies, kittens and older dogs and cats.
- Many puppies are infested with the roundworm parasites from birth, as a pregnant dog can pass the parasites to her puppies before they're born.
- All dogs and cats require regular de-worming with anti-worm medicine. See your vet for regular check-ups and for specific advice on how to treat your pet.
- The parasite eggs responsible for toxocariasis can survive for many months in sand or soil, so all pet faeces should be collected anddisposed of immediately.
Roundworm parasites are most commonly found in cats, dogs and foxes. The worms may cause sickness and diarrhoea in young animals. Adult dogs generally show no signs of ill health but still need regular worming.
If every owner treated their dog with a worming preparation, and cleared up after their dog, toxocariasis would be virtually eradicated. The eggs only become infectious after 10-21 days, so there's no immediate danger from fresh animal faeces. However, once the eggs are passed into sand or soil, they can survive for many months.
Practising good hygiene can help prevent toxocariasis. Some of the steps you can take are listed below:
- Wash your hands well with soap and warm water after handling pets or coming into contact with sand or soil.
- Teach children to always wash their hands after playing with dogs or cats, after playing outdoors and before eating.
- Wash food that may have come into contact with soil.
- Try to avoid letting children play in areas where there's a lot of dog or cat faeces.
- Teach children that it's dangerous to eat dirt or soil.