Pediatric Toxocariasis Clinical Presentation

Updated: Dec 21, 2020
  • Author: Germaine L Defendi, MD, MS, FAAP; Chief Editor: Russell W Steele, MD  more...
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The 3 clinical forms of toxocariasis traditionally described are the following:

Visceral larva migrans (VLM)

See the list below:

  • General: VLM syndrome is characterized by bouts of fever, coughing wheezing and hepatomegaly. Serology shows leukocytosis, anemia, eosinophilia, hypergammaglobulinemia, and positive Toxocara titers. The patient usually has malaise, weakness, and non-specific abdominal symptoms. VLM is diagnosed mainly in children age 1-7 years old. Systemic disease in this age group rarely results in ocular disease. Many organ systems can be involved in VLM.

  • Dermatologic:

    • Skin lesions, such as urticaria and nodules, have been described. Toxocariasis can cause chronic idiopathic urticaria, especially when associated with eosinophilia.

    • Wells syndrome is an eosinophilic cellulitis of unknown origin. A report described 2 cases with clinical and histologic features of Wells syndrome with positive anti-Toxocara titers. [20] Not only did the symptoms respond to treatment with albendazole, but the antibody titer also normalized.

    • Another study demonstrated the presence of T. canis antibodies in 65% of patients with chronic urticaria (n=51), as compared with 21% in controls (n=81), others found a seroprevalence of 20% in chronic urticaria (n=128) versus 13% in controls (n=236), a seroprevalence of 8% in chronic urticaria (n=110), a seroprevalence of 13% in children with the condition, and a seroprevalence of 30% in controls. [21]

    • Overall, studies citing toxocariasis as the cause of chronic urticaria are inconsistent.

  • Pulmonary:

    • Wheezing is a common symptom of VLM.

    • History of a chronic cough (lasting for more than 3 weeks) of a paroxysmal character with greater severity at night and associated with recurrent wheezing is reported. [19]

    • Progression to eosinophilic pneumonia and respiratory failure can occur.

    • Severe pulmonary involvement correlates with other VLM symptoms such as fever, urticaria, pronounced eosinophilia.

    • VLM can be confused with lymphoma. A case report cites a 65-year-old previously healthy male who presented with a 2-week history of fever, night sweats, weight loss, eosinophilia, and a high erythrocyte sedimentation rate. Chest radiograph revealed bilateral hilar and mediastinal lymphadenopathy and discrete bilateral pleurisy. This clinical presentation made the diagnosis unclear for either VLM or lymphoma. [22]

  • Hepatic:

    • VLM is usually associated with hepatomegaly.

    • Histology usually reveals granulomatous hepatitis.

    • Pyogenic liver abscess concomitant with Toxocara hepatitis has also been reported.

    • The spleen can be enlarged but this occurs less often than the liver.

  • Lymphatic and lymphedema:

    • Generalized lymphadenopathy is an infrequent manifestation of toxocariasis. A 24-month-old boy in whom lymphedema was the main clinical manifestation of toxocariasis has been reported. [23]

    • There have been two cases of isolated eosinophilic ascites reported due to Toxocara. [24]

  • Rheumatologic:

    • Frequently, manifestations such as arthralgias, monoarthritis, migratory cutaneous lesions, and small-vessel vasculitis coincidentally occur with VLM. Henoch-Schönlein purpura has been described in a 17-year-old male in association with anti-Toxocara IgG and IgE that spontaneously resolved. [25]

  • Cardiac:

    • All layers of the heart can be affected. The most common cardiac presentation is myocarditis. Among the unusual manifestations described in the literature are Loeffler endomyocarditis (a restrictive cardiomyopathy) [26] and pericardial tamponade. [27]

  • CNS:

    • Toxocariasis is a cause of eosinophilic meningitis, an aseptic meningitis in which the WBCs in the cerebrospinal fluid are primarily eosinophils.

    • Other less common entities described in association with VLM are encephalitis, [28] larval invasion of the brain parenchyma, seizures due to solitary mass lesions, static encephalopathy, arachnoiditis, and spinal cord lesions. [29]

Ocular larva migrans (OLM)  [30]

  • Ocular toxocariasis or OLM refers to eye (usually retinal) involvement during Toxocara infection. Larvae migrate to and invade the eyes, where they induce an eosinophilic inflammatory reaction.

  • OLM can occur in patients after a diagnosed case of systemic disease with VLM, currently with VLM, or alone without clinical evidence of VLM

  • Ocular toxocariasis is an uncommon disease that occurs primarily in young patients. [31] However, patients with OLM tend to be older (age 5-10 years old) than those with VLM (primarily age 1-4 years old).

  • Males and females are affected equally. Patients can report a history of recent exposure to puppies or kittens. Parents may report geophagic pica behavior in their children.

  • The disease is unilateral in most cases, with mild-to-moderate intermediate or diffuse inflammation. Bilateral involvement has been reported in adults.

  • Cases of isolated OLM lack systemic symptoms, such as fever, cough, and abdominal pain, and do not have marked eosinophilia. The lack of symptoms with OLM as seen in VLM, suggest that visceral and ocular manifestations are separate clinical entities. [5] .

  • Loss of visual acuity, leukocoria (white pupillary reflex), strabismus, and ocular pain are clinical findings.

    • There is no pathognomonic presentation for OLM.

    • Ophthalmological evaluation is fostered due to uveitis, endophthalmitis, strabismus or impaired vision.

    • Other presentations of OLM include endophthalmitis with secondary retinal detachment, retinal granulomas, uveitis, vitreous abscess, and optic neuritis.

    • These clinical findings can be mistaken for retinoblastoma. OLM has been cited as a cause of pseudo-retinoblastoma.

      • Tools to differentiate are ocular ultrasonography, serology ELISA for T. canis, and cytology of aqueous humor. [32]

  • Among patients with uveitis, ocular toxocariasis is relatively uncommon. In a review of 2,185 patients with uveitis, OLM was the etiology in 22 patients (1%). [33] Of these 22 patients, the following findings were present.

    • Mean patient age was 16.5 years.

    • Inflammation was unilateral in 91% of cases.

    • The most common symptoms present in Toxocara uveitis were blurred vision (75%), pain or photophobia (33.3%), and ocular floaters (16.7%).

    • Presentation consisted of a granuloma in the peripheral retina in 50% of cases, granuloma in the macula in 25% of cases, and moderate-to-severe vitreous inflammation, mimicking endophthalmitis in 25% of cases.

    • Serum ELISA for antibodies to Toxocara was positive in 11 patients (50%), negative in 8 patients (36.4%), and unknown in 3 patients (13.6%).

    • Four patients tested for vitreous or aqueous ELISA showed positive titers (2 had negative serologic titers), confirming that seronegativity does not exclude the diagnosis.

    • The primary causes of vision loss were vitreitis, cystoid macular edema, and traction retinal detachment.

Covert toxocariasis

See the list below:

  • Covert toxocariasis, also called common toxocariasis, refers to a less specific syndrome that was recognized with the wider use of serodiagnostic assays for Toxocara infection.

  • Most cases of covert toxocariasis are asymptomatic.

  • Symptoms, if present, tend to be mild and nonspecific such as chronic or recurrent abdominal pain, hepatomegaly, cough, sleep disturbances, headache, malaise, anorexia, and failure to thrive.

  • Pulmonary wheezing may be the only presenting symptom.

  • Eosinophilia is less frequent and less pronounced with this covert form than with VLM. Toxocara antibody titers are also lower.

Clinical manifestations

The clinical manifestations of T canis infections depend on the following factors:

  • Number of infective eggs

  • Duration of infection

  • Anatomic location of the larvae

  • Host immune response



See the list below:

  • VLM

    • General: Systemic toxocariasis consists of wheezing, hepatomegaly, and, occasionally, mild abdominal tenderness.

    • Dermatologic: Urticaria and nodules are common. Cellulitis may occur in Wells syndrome.

    • Pulmonary: Wheezing is typical. Evidence of pleural effusions is rarely noted.

    • Hepatic: VLM is usually associated with hepatomegaly. Hepatosplenomegaly has been reported.

    • Lymphatic: Generalized lymphadenopathy is an infrequent manifestation.

    • Rheumatologic: Monoarthritis, migratory cutaneous lesions, and evidence of small-vessel vasculitis may be present.

    • Cardiac: Findings suggestive of myocarditis are the most common.

    • CNS: A stiff neck and focal neurologic signs may be present.

  • OLM

    • Loss of visual acuity

    • Leukocoria

    • Strabismus

    • Secondary retinal detachment

    • Uveitis

    • Vitreous abscess

    • Optic neuritis

  • Covert toxocariasis

    • Wheezing

    • Hepatomegaly

    • Abdominal tenderness

    • Failure to thrive



See the list below:

  • The primary causes of toxocariasis are T canis and T catis.

  • Toxocara species are not the only causes of OLM and VLM; others include Baylisascaris procyonis, Gnathostoma spinigerum, Trichinella spiralis, and Angiostrongylus and Anisakis species. Other causes include A suum (especially in Japan); Angiostrongylus cantonensis or Angiostrongylus costaricensis; and, much less commonly, ascarids from salt-water fishes, such as members of the genera Phocanema, Anisakis, and Contracaecum.

  • Cutaneous larva migrans is caused by Ancylostoma duodenale.