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Toxocariasis in Adult
Other Resources UpToDate PubMed

Toxocariasis in Adult

Contributors: Vivian Wong MD, PhD, Susan Burgin MD, Edith Lederman MD, Noah Craft MD, PhD
Other Resources UpToDate PubMed


Toxocariasis is a common zoonosis caused by 2 species of Toxocara roundworms: Toxocara canis from dogs and, less commonly, Toxocara cati from cats. It may be found wherever these animals and their respective roundworms can flourish. It is more common in developing countries but is also seen in temperate regions (eg, seropositivity in the United States ranges from 2.5% to 54%). Human infection may occur via accidental ingestion of the eggs from the environment, such as soil contaminated with dog or cat feces, or from ingestion of uncooked animal meat infested with Toxocara larvae.

Toxocariasis occurs most commonly in children due to their poor hygiene and play habits. Two general clinical subcategories exist: ocular and visceral. Visceral infection is mainly seen in children younger than 6 years of age. Ocular manifestations are mainly seen in children 6 years and older.

The range of clinical manifestations is wide. Most patients are asymptomatic. Others may present with generalized pruritus and/or urticaria but without localizing signs or symptoms. Still others may present with wheezing, fever, abdominal pain, and hepatomegaly.

In ocular toxocariasis, patients will present with unilateral visual impairment and/or strabismus. Blindness may occur. Rarely, T. canis larvae can cause eosinophilic meningitis.

Risk factors include exposure to dogs / cats (particularly puppies or kittens), pica (ingestion of non-nutritive substances), lower socioeconomic status, and intellectual disability (institutionalized).


B83.0 – Visceral larva migrans

87121004 – Visceral larva migrans syndrome

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Differential Diagnosis & Pitfalls

  • Unlike toxocariasis, Baylisascariasis (raccoon parasite) often involves the central nervous system.
  • Schistosomiasis is associated with freshwater exposure in tropical areas, and the patient may present with lower extremity pruritic papules during parasite penetration.
  • Liver fluke infections (Opisthorchis viverrini infection, Clonorchiasis) usually are associated with ingestion of raw fish and usually do not present with skin findings.
  • Echinococcosis usually does not present with skin findings and has characteristic liver or lung findings on ultrasound or CT scan.
  • Urticaria
  • Urticarial vasculitis
  • Contact dermatitis (Irritant contact dermatitis, Allergic contact dermatitis)
  • Pruritus without rash
  • Scabies
  • Atopic dermatitis
  • Pruritus of senescence 
  • Drug eruption general overview

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Last Updated:10/01/2018
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Toxocariasis in Adult
A medical illustration showing key findings of Toxocariasis (Visceral) : Abdominal pain, Cough, Fever, Hepatomegaly, Hypergammaglobulinemia, Pruritus, Wheezing, WBC elevated, EOS increased, Dog exposure, Cat exposure
Clinical image of Toxocariasis - imageId=1534666. Click to open in gallery.  caption: 'Hyperpigmented macules on the abdomen and flank.'
Hyperpigmented macules on the abdomen and flank.
Copyright © 2024 VisualDx®. All rights reserved.