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Toxocariasis (Larva Migrans)

Zoonotic helminth infection from dog and cat roundworm larvae

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Internal Medicine department. Book Appointment →

What is Toxocariasis (Larva Migrans)?

Toxocara canis and Toxocara cati are common ascarid nematodes of dogs and cats. Eggs passed in feces become infectious in soil after 2-4 weeks. Humans, particularly young children with geophagia, ingest embryonated eggs from contaminated soil, sandboxes, or hands. Larvae hatch in the small intestine and migrate via portal circulation to liver, lungs, eyes, brain, and other tissues but cannot mature to adults in humans, resulting in larva migrans syndromes.

Visceral larva migrans (VLM) most commonly affects children with eosinophilia, hepatomegaly, pulmonary symptoms, fever, abdominal pain, and rash. Ocular larva migrans (OLM) typically presents in older children and adolescents as unilateral leukocoria, strabismus, or vision loss with retinal or papillary granuloma, vitreous traction, and tractional retinal detachment. Neurotoxocariasis presents as eosinophilic meningoencephalitis, myelitis, or focal lesions.

Diagnosis is supported by clinical features, eosinophilia, elevated total IgE, and Toxocara excretory-secretory antigen ELISA serology with confirmation by Western blot. Histology may demonstrate larvae or characteristic eosinophilic granulomas. Treatment is with albendazole (preferred) or mebendazole, with corticosteroids as adjunct for ocular and CNS disease to control inflammation. Prevention focuses on dog and cat deworming, hand hygiene, sandbox covering, and public health education.

Symptoms

Visceral larva migrans (VLM): fever, hepatomegaly, abdominal pain, cough, wheezing, urticarial rash, eosinophilia
Ocular larva migrans (OLM): unilateral leukocoria, strabismus, vision loss
Retinal or papillary granuloma on fundus examination
Tractional retinal detachment
Vitreous traction, vitreous opacities
Endophthalmitis-like presentation
Anterior or posterior uveitis
Neurotoxocariasis: meningoencephalitis, seizures, focal neurological deficits
Eosinophilic meningitis
Myelitis
Cerebellar ataxia
Asymptomatic seropositivity (most common scenario)
Lymphadenopathy
Anemia
Hypergammaglobulinemia
Eosinophilic pneumonia
Loeffler-like pulmonary syndrome
Asthma exacerbations (controversial association)
Covert toxocariasis (mild non-specific symptoms with seropositivity)
Common toxocariasis (hepatic enlargement, eosinophilia)

Risk Factors

Geophagia (eating soil) in children
Pica behavior
Young age (1-7 years for VLM, older for OLM)
Living in or visiting areas with high stray dog population
Soil exposure (gardening, agriculture)
Sandbox play (often contaminated)
Contact with puppies and kittens (especially young)
Lack of dog and cat deworming
Poor hand hygiene
Lower socioeconomic status
Tropical and subtropical residence (higher prevalence)
Rural residence
Hunters consuming undercooked game (paratenic hosts)
Consumption of raw or undercooked liver
Contaminated vegetables eaten raw
Public parks and playgrounds with poor sanitation
Daycare attendance
Immunocompromised state (more severe disease)
Pre-existing eye disease (worsens OLM impact)
Family history of pet ownership without deworming

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Child with unexplained eosinophilia
  • Hepatomegaly with eosinophilia
  • Pulmonary symptoms with eosinophilia (eosinophilic pneumonia)
  • Leukocoria or strabismus in child
  • Unilateral vision loss in child or adolescent
  • Eosinophilic meningitis or encephalitis
  • Recurrent urticaria with eosinophilia
  • Persistent abdominal pain in child with pet exposure
  • History of geophagia with systemic symptoms
  • Asymptomatic seropositivity for guidance
  • Family history with similar exposures
  • Migrants from highly endemic regions

Treatment Methods

01
Comprehensive history including soil and pet exposure
02
Physical examination with abdominal, pulmonary, ocular, neurological focus
03
Complete blood count with differential (eosinophilia hallmark)
04
Total IgE level (often markedly elevated)
05
Toxocara excretory-secretory antigen ELISA serology
06
Western blot for confirmation
07
Liver function tests, abdominal imaging if hepatic involvement
08
Chest imaging if pulmonary symptoms
09
Dilated fundus examination by ophthalmologist for OLM
10
OCT and fluorescein angiography for ocular involvement
11
Brain MRI and lumbar puncture for neurotoxocariasis
12
CSF analysis with eosinophilic pleocytosis confirmation
13
Tissue biopsy with histopathology when accessible
14
Albendazole 400-800 mg twice daily for 5-21 days (preferred for systemic disease)
15
Mebendazole 100-200 mg twice daily for 5 days as alternative
16
Diethylcarbamazine in selected cases (less commonly used)
17
Corticosteroids (prednisone 1-2 mg/kg/day) for ocular, CNS, and severe systemic inflammation
18
Topical corticosteroids and cycloplegics for ocular involvement
19
Periocular or intravitreal corticosteroid for OLM
20
Vitrectomy for tractional retinal detachment
21
Cryotherapy or laser photocoagulation for retinal granuloma
22
Anti-VEGF for choroidal neovascularization (rare)
23
Supportive care for severe systemic disease
24
Hand hygiene and pica behavior counseling
25
Pet deworming with public health education
26
Sandbox covering and park sanitation
27
Avoid raw or undercooked meat
28
Multidisciplinary care: pediatrics, infectious disease, ophthalmology, neurology
29
Long-term follow-up for ocular sequelae and neurological recovery

Which Department to Visit?

You can visit our Enfeksiyon Hastalıkları department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.