Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 35-29: Toxocariasis + Key Features Download Section PDF Listen +++ +++ Essentials of Diagnosis ++ Principally seen in young children Most infections are asymptomatic Liver and lungs most commonly involved organs CNS infection is rare Ocular larva migrans is distinct syndrome that occurs in children older than is typical for visceral larva migrans +++ General Considerations ++ Caused by the dog roundworm Toxocara canis or by the cat roundworm Toxocara cati Rarely, Baylisascaris procyonis, a roundworm of raccoons, causes visceral larva migrans in humans Humans are infected after ingestion of eggs in material contaminated by dog or other feces With T canis, infection is spread principally by puppies and lactating females, and the eggs must be on the ground for several weeks before they are infectious After ingestion by humans, larvae migrate to various tissues but cannot complete their life cycle + Clinical Findings Download Section PDF Listen +++ +++ Symptoms and Signs ++ Most infections are asymptomatic Cough, fever, wheezing Hepatomegaly, splenomegaly Lymphadenopathy Pulmonary infiltrates Eosinophilia Involvement of the CNS can occur rarely, leading to eosinophilic meningitis and other abnormalities Ocular larva migrans presents with Visual deficits Pain Retinal mass, which can be confused with retinoblastoma Manifestations of B procyonis infection, although rare, are typically similar but more severe than those with T canis +++ Differential Diagnosis ++ Acute HIV infection Infectious mononucleosis Lymphoma Malaria Ascariasis Chagas disease Retinoblastoma + Diagnosis Download Section PDF Listen +++ +++ Laboratory Tests ++ Blood tests may show eosinophilia in patient with hepatomegaly or other signs of disease Serologic tests may be helpful ELISA against a group of excreted antigens has shown good sensitivity and specificity Molecular assays can identify specific pathogens +++ Diagnostic Procedures ++ Diagnosis is confirmed by identification of larvae in a biopsy of infected tissue, usually performed when other diseases are suspected + Treatment Download Section PDF Listen +++ +++ Medications ++ Most patients recover without specific therapy Antihelminthics or corticosteroids may be considered in severe cases Although no drugs have been proved to be effective, the following have been used Albendazole Mebendazole Diethylcarbamazine Ivermectin Albendazole (400 mg twice daily for 5 days) has been recommended as treatment of choice + Outcome Download Section PDF Listen +++ +++ Prevention ++ Disease in humans is best prevented by periodic treatment of puppies, kittens, and nursing dog and cat mothers, starting at 2 weeks postpartum, repeating at weekly intervals for 3 weeks and then every 6 months Prevent defecation by dogs and cats in areas where children play +++ Prognosis ++ Symptoms of the acute infection may persist for months but generally clear within 1–2 years The ultimate outcome is usually good, but permanent neuropsychological deficits have been seen Partial or total permanent visual impairment is rare +++ When to Refer ++ Patients whose disease is progressive despite therapy All patients with ocular toxocariasis +++ When to Admit ++ Progressive respiratory disease Patients with CNS involvement or carditis + References Download Section PDF Listen +++ + +Chen J et al. Toxocariasis: a silent threat with a progressive public health impact. Infect Dis Poverty. 2018 Jun 13;7(1):59. [PubMed: 29895324] + +Ma G et al. Human toxocariasis. Lancet Infect Dis. 2018 Jan;18(1):e14–24. [PubMed: 28781085]