Toxocariasis in Children: Symptoms, Treatment, and Prevention

Toxocariasis is an infection caused by the larval stage of roundworms that usually live in the intestines of dogs and cats. Children are affected more often than adults because they play close to the ground and may accidentally swallow parasite eggs from contaminated soil or surfaces.

Most infections are mild or cause no symptoms at all, but in some children the larvae can travel through the body and inflame important organs such as the liver, lungs, or eyes, sometimes leading to serious complications like breathing problems or vision loss.

Understanding the Parasite: What Is Toxocariasis?

The term toxocariasis refers to human infection with larvae of Toxocara roundworms, mainly:

• Toxocara canis – the dog roundworm
• Toxocara cati – the cat roundworm

Dogs and cats can carry adult worms in their intestines. The worms release eggs that are passed in the animal’s feces. Those eggs become infectious in soil or sand after a few weeks. When a child accidentally swallows these microscopic eggs, the eggs hatch into larvae inside the intestines and then migrate to other parts of the body.

Main Types of Disease in Children

How Children Become Infected

Children do not catch toxocariasis from casual touching or petting a dog or cat. Instead, infection occurs when they swallow parasite eggs from contaminated material.

Common Routes of Infection

• Playing in contaminated soil or sand, such as sandboxes, playgrounds, or yards where infected dogs or cats defecate.
• Putting dirty hands or objects in the mouth after playing on the ground, especially when handwashing is skipped.
• Contact with pet feces during cleanup if hands are not washed properly afterward.
• Eating unwashed vegetables grown in soil contaminated with dog or cat feces.

Young children, particularly toddlers and preschoolers, are at higher risk because they often crawl, dig in dirt, and explore the world by putting their hands or toys into their mouths.

Who Is Most at Risk?

Any child who has close contact with soil, sand, or areas where animals defecate can be exposed. Certain situations increase risk:

• Living in homes with puppies, kittens, or outdoor cats and dogs that are not routinely dewormed.
• Playing often in public parks or uncovered sandboxes.
• Limited access to safe play spaces, leading kids to play near trash areas or open lots.
• Poor hand hygiene due to lack of supervision or handwashing facilities.

In many communities around the world, toxocariasis is considered a neglected infection of poverty and is more common in areas with many stray animals and limited access to veterinary care.

Signs and Symptoms Parents Should Watch For

Most infected individuals never develop noticeable illness. When symptoms do occur, they vary depending on which organs the larvae affect.

General Features

• Symptoms often start several weeks after a child has ingested the eggs.
• Some children have only mild, nonspecific complaints, while others develop more obvious signs of inflammation in a specific organ.

Symptoms of Visceral (Internal Organ) Toxocariasis

When larvae travel through internal organs such as the liver and lungs, children may experience:

• Fever
• Cough or wheezing that may resemble asthma
• Abdominal (belly) pain
• Enlarged liver (sometimes the doctor feels this on exam)
• Fatigue or general feeling of being unwell
• Occasionally, skin rash or enlarged spleen

Symptoms of Ocular (Eye) Toxocariasis

When larvae lodge in the eye, they can cause inflammation and scarring. Parents or older children might notice:

• Redness or irritation of one eye
• Seeing spots, floaters, or flashes of light
• Blurred vision or decreased vision in one eye
• An abnormally colored pupil in photographs

Ocular toxocariasis typically affects only one eye and, if untreated, may lead to permanent vision loss.

When to Call the Doctor

Contact your child’s healthcare provider promptly if:

• Your child has prolonged fever, coughing, or wheezing not explained by a cold or asthma.
• There is ongoing abdominal pain without a clear cause.
• You notice eye redness, visual changes, or complaints about dark spots or flashes of light in one eye.
• Your child has such symptoms and frequently plays in areas where dog or cat feces might be present.

These symptoms can also be caused by many other, more common illnesses. The doctor will use your child’s history, physical exam, and selected tests to decide whether toxocariasis should be considered.

How Doctors Diagnose Toxocariasis

There is no single test that by itself proves toxocariasis in every case. Doctors combine several pieces of information.

1. Medical History and Physical Examination

• Questions about contact with dogs and cats, especially young animals.
• Exposure to soil, sandpits, or yards that might be contaminated.
• Review of symptoms such as fever, cough, belly pain, or visual problems.
• Physical signs like enlarged liver or spleen, breathing changes, or eye abnormalities.

2. Blood Tests

• Complete blood count may show high eosinophil levels (a type of white blood cell often elevated in parasitic infections).
• Specific antibody testing (ELISA) for Toxocara can support the diagnosis, although a positive result does not always mean current active disease.

3. Imaging and Eye Evaluation

• In visceral disease, ultrasound or other imaging might be used to evaluate liver or lung inflammation.
• In suspected eye disease, a comprehensive eye exam by an ophthalmologist is crucial to look for retinal lesions or other signs typical of ocular toxocariasis.

Because the symptoms and test results can overlap with those of other conditions, toxocariasis is often a “diagnosis of suspicion” supported by exposure history and test findings.

Treatment Options for Children

Treatment depends on the severity of illness, which organs are involved, and the child’s overall health. Many mild infections resolve without specific medication, but more serious disease usually needs therapy.

Antiparasitic Medicines

The main drugs used to kill migrating larvae are:

• Albendazole – a broad-spectrum antiparasitic
• Mebendazole – another medicine in the same family

These medications are typically taken by mouth for several days. The exact dose and duration are decided by the child’s doctor, based on age, weight, and type of disease. According to expert guidance, both medicines are commonly used in children and have been given safely even to children as young as one year old in deworming campaigns, though dosing may be adjusted for younger ages.

Treating Visceral Toxocariasis

• Children with moderate or severe symptoms such as significant fever, lung involvement, or liver inflammation are usually treated with albendazole or mebendazole.
• Some cases may also require anti-inflammatory medications (such as steroids) if organ inflammation is severe, based on specialist judgment.

Treating Ocular Toxocariasis

When the eye is involved, treatment aims to limit inflammation and preserve vision:

• Corticosteroids (by mouth, injection, or eye drops) to decrease inflammation.
• Albendazole or mebendazole may be used to help kill active larvae.
• Eye surgery can be considered in selected cases to repair retinal damage or remove scar tissue, especially when the disease is no longer active but has caused structural problems.

Because improper treatment can worsen vision, ocular toxocariasis should always be managed together with a pediatric eye specialist.

Possible Complications

With appropriate care, many children recover well. However, when infection is not recognized or is very severe, complications can occur:

• Persistent breathing problems from lung involvement
• Chronic liver inflammation or scarring in severe, prolonged cases
• Permanent vision loss or retinal detachment in ocular disease

Early recognition of symptoms and timely evaluation increase the chances of preventing long-term damage, especially to a child’s eyesight.

Preventing Toxocariasis at Home and in the Community

Toxocariasis is largely preventable with a combination of good hygiene, responsible pet care, and safe play environments.

1. Pet Care Practices

• Regular veterinary visits for dogs and cats, including routine deworming starting when they are puppies or kittens.
• Follow your vet’s schedule for repeat deworming, especially for outdoor animals.
• Do not allow pets to roam freely where they can defecate in children’s play areas.

2. Safe Handling of Pet Waste

• Pick up dog feces from yards, sidewalks, and parks as soon as possible.
• Dispose of waste in sealed bags in the trash.
• Always wash hands thoroughly after handling pet waste or cleaning litter boxes.

3. Protecting Play Areas

• Cover sandboxes when not in use to keep cats and other animals from using them as litter boxes.
• Encourage children to avoid playing in areas heavily soiled with animal feces or in abandoned lots.

4. Teaching Children Good Hygiene

• Help children wash their hands with soap and water after playing outside, before eating, and after touching pets.
• Discourage hand-to-mouth behaviors such as nail-biting or sucking on dirty fingers or toys.
• Rinse and, when appropriate, peel fruits and vegetables that might have been grown in soil accessible to animals.

Living With Pets Safely

Families do not need to give up beloved pets to protect children from toxocariasis. Instead, the focus should be on responsible ownership and clean habits.

• Keep vaccinations and deworming up to date for all household pets.
• Designate specific toilet areas for dogs and clean them regularly.
• Teach children to wash hands after playing with pets and before meals.
• Discourage children from letting pets lick their faces or mouths.

By combining veterinary care with personal hygiene and environmental cleanliness, the risk of toxocariasis and many other zoonotic infections can be greatly reduced.

Frequently Asked Questions (FAQs)