Toxocariasis is an uncommon infection caused by parasites that are known as toxocara canis (from dogs) and toxocara cati (from cats). Theyare more commonly known as roundworms.
Toxocariasis is a zoonotic condition. Zoonotic conditions are spread from animals to humans.
The toxocara parasites live in the digestive system of dogs and foxes and cats. Parasite eggs can be released in the faeces of infected animals and contaminate soil. If someone accidently ingests small particles of contaminated soil, they may develop toxocariasis.
Types of toxocariasis
The symptoms of toxocariasis can vary depending on where in the body the infection occurs. There are three main types of toxocariasis:
- covert toxocariasis
- visceral larva migrans
- ocular larva migrans
Covert toxocariasis is the most common and mildest form of toxocariasis. Symptoms of covert toxocariasis include abdominal pain, a cough and headache.
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 main symptoms of visceral larva migrans are fever, abdominal pain and shortness of breath.
Ocular larva migrans
Ocular larva migrans is the least common but potentially most serious type of toxocariasis. The condition can develop if the toxocara canis parasites move into the eyes.
The main symptoms of ocular larva migrans 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.
How common is toxocariasis?
Toxocariasis is a rare condition, with an average of 10 cases occurring each year in England. As the disease is not notifiable in Ireland, we do not have any clear indication as to the number of cases here. However, it is likely to be as uncommon in Ireland as it is in England.
Toxocariasis usually affects children who are between one and four years old. However, cases of toxocariasis have been reported in people of all ages.
Young children are particularly at risk of getting toxicariasis 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.
With treatment, the outlook for toxocariasis is very good. Treatment involves taking medication designed to kill the parasites. Most people will quickly make a full recovery and will not experience any long-term complications.
Due to advances in treatment, the potential risk of blindness is now a very rare complication of toxocariasis.