Toxocariasis

Toxocariasis is an illness of humans caused by the dog roundworm (Toxocara canis) and, less frequently, the cat roundworm (Toxocara cati).^[1] These are the most common intestinal roundworms of dogs, coyotes, wolves and foxes and domestic cats, respectively.^[2] Humans are among the many "accidental" or paratenic hosts of these roundworms.^[3]

While this zoonotic infection is usually asymptomatic, it may cause severe disease. There are three distinct syndromes of toxocariasis: covert toxocariasis is a relatively mild illness very similar to Löffler's syndrome. It is characterized by fever, eosinophilia, urticaria, enlarged lymph nodes, cough, bronchospasm, wheezing, abdominal pain, headaches, and/or hepatosplenomegaly. Visceral larva migrans (VLM) is a more severe form of the disease; signs and symptoms depend on the specific organ system(s) involved. Lung involvement may manifest as shortness of breath, interstitial lung disease, pleural effusion, and even respiratory failure. Brain involvement may manifest as meningitis, encephalitis, or epileptic seizures. Cardiac involvement may manifest as myocarditis. Ocular larva migrans (OLM) is the third syndrome, manifesting as uveitis, endophthalmitis, visual impairment or even blindness in the affected eye.^[4]