Toxocariasis in Children: Symptoms, Treatment and Prevention

Toxocariasis is a parasitic infection that humans can get from roundworms found mainly in dogs and cats. It can sound frightening, especially because it sometimes affects a child’s eyes or internal organs, but in most cases it is preventable and often mild. This guide explains what parents need to know, using simple language and up-to-date medical information.

What Exactly Is Toxocariasis?

The term toxocariasis refers to infection with larvae of the roundworms Toxocara canis (dog roundworm) or Toxocara cati (cat roundworm). These worms normally live in the intestines of dogs and cats, where they produce eggs that pass out in the animal’s stool.

• Host animals: dogs (especially puppies) and cats
• Type of germ: parasitic roundworm (a nematode)
• Human role: humans are “accidental hosts” – the worms cannot complete their life cycle in people

In people, the swallowed eggs release larvae that can travel through the body but do not grow into adult worms in the intestines as they do in animals.

How Children Become Infected

Children usually get toxocariasis by swallowing microscopic Toxocara eggs from contaminated soil or surfaces. You cannot see these eggs with the naked eye.

Typical Ways Infection Happens

• Playing in contaminated soil or sand where infected dogs or cats have defecated (yards, sandboxes, parks)
• Dirty hands going into the mouth after outdoor play
• Unwashed raw vegetables grown in soil containing infected animal feces
• Contact with animal fur that may have tiny amounts of contaminated soil or feces

The risk is higher when:

• Dogs and cats are not dewormed regularly
• Pet feces are not picked up promptly in yards or public spaces
• Children have habits like pica or geophagia (eating dirt or non-food items)

What Happens in the Body?

Once the eggs are swallowed, they hatch into larvae in the intestine and then move into the bloodstream. From there, they may travel to the:

• Liver
• Lungs
• Eyes
• Brain or other organs (less commonly)

The body’s immune system reacts to these larvae, which causes inflammation and the symptoms of disease. Depending on where they travel, doctors describe different forms of toxocariasis.

Who Is Most at Risk?

Although anyone can become infected, children are affected more often, especially those between about 1 and 10 years old.

Higher risk is seen when:

• Children frequently play on the ground or in sandboxes
• There are many free-roaming or stray dogs and cats
• Pet deworming and feces disposal are not done regularly
• Access to clean running water or handwashing facilities is limited

Signs and Symptoms Parents Should Watch For

Many people with toxocariasis never feel sick and only a blood test reveals that they were infected at some point. When symptoms do appear, they depend mainly on where the larvae have migrated.

General (Often Mild) Symptoms

• Fever or low-grade temperature
• Tiredness, feeling unwell
• Loss of appetite or weight loss
• Rash or itchy skin in some cases

Symptoms of Visceral Toxocariasis

• Coughing or wheezing that may be mistaken for asthma or bronchitis
• Abdominal (belly) pain
• Enlarged liver or sometimes enlarged spleen, noticed by a doctor on exam or ultrasound
• Occasional chest pain or trouble breathing from lung inflammation

Symptoms of Ocular Toxocariasis

Ocular disease usually affects one eye and may be the first and only sign of toxocariasis. Call an eye doctor or pediatrician urgently if your child has:

• Eye redness or irritation that does not improve
• Complaints of seeing spots, dots, or flashes of light (often called “floaters”)
• Blurred vision or areas of missing vision
• Sudden or slowly worsening loss of sight in one eye
• An oddly colored or white-looking pupil (noticed in photos or direct view)

Rare but Serious Complications

In unusual cases, larvae may affect the brain, spinal cord, or heart. This is called neurotoxocariasis when the nervous system is involved. Symptoms may include seizures, balance problems, or other neurologic issues. These forms are rare but require rapid medical attention.

When to Call the Doctor

Contact your child’s healthcare provider if:

• Your child has ongoing cough, wheezing, or abdominal pain without a clear explanation
• There is a combination of fever, high eosinophil count on a blood test, and risk factors such as contact with puppies, kittens, or soil possibly contaminated by pet feces
• Your child shows any eye symptoms listed above, especially vision changes in one eye

Tell the doctor about:

• Pets at home or in the neighborhood
• Whether pets are dewormed regularly
• Recent travel, especially to areas with many stray animals
• Habits such as soil-eating, nail biting, or frequent hand-to-mouth activity

How Doctors Diagnose Toxocariasis

There is no single perfect test, so doctors put together information from the history, physical exam, blood work, and sometimes imaging.

Common Diagnostic Tools

• Detailed history and exam to look for organ enlargement, wheezing, rash, or eye changes
• Blood tests
  • Eosinophil count (a type of white blood cell often increased in parasitic infections)
  • Serologic tests that look for antibodies to Toxocara (e.g., ELISA)
• Imaging
  • Ultrasound of the abdomen to assess the liver and spleen
  • Chest X-ray if lung symptoms are present
• Eye examination by an ophthalmologist for suspected ocular disease, often using dilated eye exam and imaging of the retina

It is important to know that a positive blood test for Toxocara antibodies does not always mean active disease; it may simply show that the child was exposed in the past. Doctors interpret the test in the context of symptoms and other findings.

Treatment Options for Children

Many people with mild or asymptomatic toxocariasis may not need medicine, because the infection can gradually clear on its own. When treatment is needed, doctors use antiparasitic medications that kill the larvae.

Medications Used

• Albendazole – often the first choice for visceral toxocariasis
• Mebendazole – an alternative antiparasitic drug

For ocular disease, treatment is more complex and may involve:

• Systemic antiparasitic medication (albendazole or mebendazole) in active disease
• Corticosteroids (eye drops, oral, or injected) to reduce inflammation and protect the eye
• Eye surgery or laser treatments in some cases to remove scar tissue, treat retinal problems, or prevent further damage

According to guidance referenced by the U.S. Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO), albendazole has been used safely in many children, including some younger than 6 years, when dosed appropriately and monitored. However, the exact choice of drug and duration is always individualized by the pediatrician or specialist.

Monitoring and Follow-Up

• Repeat visits to review symptoms and physical exam findings
• Occasional follow-up blood tests to monitor eosinophil counts or antibody levels
• Regular eye examinations for any child with ocular involvement, sometimes for years, to detect late complications

Long-Term Outlook (Prognosis)

The overall outlook for most children with toxocariasis is generally good, especially if diagnosis and treatment occur early.

• Many mild infections resolve without leaving long-term problems
• Visceral disease usually improves with antiparasitic therapy and supportive care
• The main concern is permanent vision loss in cases of ocular toxocariasis, especially when diagnosis is delayed

Keeping up with follow-up appointments and eye checks is crucial to protect your child’s sight.

Practical Steps to Prevent Toxocariasis

Prevention relies on blocking the path from infected animal feces to a child’s mouth. Simple hygiene and pet care habits make a major difference.

Safe Pet Practices

• Have your dogs and cats dewormed regularly as advised by your veterinarian, especially puppies and kittens, which are more likely to carry Toxocara.
• Keep pet vaccinations and general health checkups up to date.
• Discourage pets from defecating in children’s play areas.

Clean Environment

• Pick up dog and cat feces promptly from yards, sidewalks, and parks.
• Cover sandboxes when not in use to prevent animals from using them as litter boxes.
• Encourage local community or school programs for proper pet waste disposal where possible.

Handwashing and Food Safety

• Teach children to wash hands with soap and water after playing outside, touching pets, or helping in the garden, and always before eating.
• Wash and peel raw fruits and vegetables, especially if grown in soil fertilized with animal manure.
• Discourage habits like nail biting, thumb-sucking, or eating dirt (pica) whenever possible.

Living with Pets and Staying Safe

Having pets and keeping your children safe from toxocariasis can go hand in hand. With good veterinary care, hygiene, and supervision, the benefits of pet ownership can be enjoyed while keeping infection risks low.

• Choose a veterinarian and follow their deworming schedule for every pet.
• Involve children in simple pet care routines like brushing and feeding, but handle waste and litter boxes only with adult supervision and gloves.
• Use outdoor shoes for play areas, and avoid walking barefoot where dogs and cats commonly defecate.

Frequently Asked Questions (FAQs)

Q: Can my child catch toxocariasis directly from touching our dog or cat?

A: Direct contact with fur is not usually the main route of infection. The biggest risk is from ingesting Toxocara eggs in soil or feces. However, fur can sometimes carry tiny particles of contaminated dirt, so handwashing after handling pets is still important.

Q: Are all dogs and cats carrying Toxocara?

A: No. Many pets are free of infection, especially when dewormed regularly. Puppies and kittens, stray animals, or pets that are not dewormed are more likely to carry Toxocara.

Q: Is toxocariasis contagious between people?

A: There is no evidence that toxocariasis spreads from person to person. People become infected by swallowing eggs from contaminated environments, not from casual contact with someone who is infected.

Q: Does my child need to be tested if we have pets?

A: Routine testing is not recommended for every child with pets. Doctors usually consider testing when a child has suggestive symptoms (such as persistent abdominal pain, cough, or unexplained eosinophilia) and known risk factors like exposure to contaminated soil or young, un-dewormed animals.

Q: What can I do today to lower my child’s risk?

A: Arrange deworming for all pets, clean up pet feces promptly, make sure sandboxes are covered, reinforce handwashing after outdoor play and before meals, and wash fruits and vegetables thoroughly. These simple steps significantly reduce the chance of toxocariasis as well as other infections.