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Table 1 Characteristics of the different clinical forms of toxocariasis

From: Toxocariasis: a silent threat with a progressive public health impact

Clinical syndromes Population Involved sites Associated symptoms
VLM Children aged 2–7 years Liver, heart, lungs, kidneys, and muscle Fever, respiratory symptoms (such as cough, wheeze, dyspnoea, bronchospasm, asthma), hepatomegaly, abdominal pain, vomiting, diarrhoea, anorexia, weight loss, fatigue, neurological manifestations, and pallor [1, 52].
OT Children aged 5–10 years Eye Toxocara larval invasion of the peripheral retina and vitreous can cause three major clinical types of OT syndrome over days to weeks: diffuse nematode endophthalmitis, peripheral inflammatory mass type and posterior pole granuloma type [104, 117119]. Also, diffuse unilateral subacute neuroretinitis (DUSN), bilateral distal symmetric sensory neuropathy (DSN), and choroidal neovascular membrane formation have been attributed to prolonged Toxocara infection [1, 120, 121]. Predominantly unilaterally or uncommon bilateral ocular involvement, characterized by visual impairment, strabismus, leukocoria, solid retinal mass predominantly at the posterior pole, vitreous mass or haze, retinal detachment, cataract, endophthalmitis, papillitis, uveitis, as well asvisual loss, vitritis, papillitis and evanescent outer retinal lesions leading to optic atrophy, retinal-artery narrowing and diffuse-pigment epithelial degeneration [1, 122,123,124,125].
CT Children and adults No specific sites In adults: breathing difficulties, rash, pruritus, weakness, and abdominal pain, elevated titers of anti-Toxocara antibodies, eosinophilia, and elevated total IgE levels [126]. In children: pyrexia, headache, loss of appetite, nausea, emesis, lethargy, behavior and sleep disorders, abdominal pain, pharyngitis, pneumonia, cough, wheeze, itching, rash, limb pains, cervical lymphadenitis, pruritus, rash, and hepatomegaly [52].
NT Children and adults Brain and spinal cord Headache, fever, photophobia, weakness, dorsalgia, confusion, tiredness, visual impairment, epileptic seizures, neuropsychological disturbances, dementia and depression [7, 127,128,129]. Motor impairment can also be observed in clinical NT cases, such as ataxia, rigor, para- or tetraparesis dysaesthesia, urinary retention, and faecal incontinence [7, 107, 130, 131]. Rarely recognizable neurological signs of eosinophilic meningitis, encephalitis, myelitis, cerebral vasculitis, epilepsy, neuropsychologic deficits or combined pathological presentations, which may be associated with repeated low dose infections, or cerebral vasculitis under anthelmintic therapy, optic neuritis, other cranial nerve involvement, and meningo-radiculitis [6, 7, 127, 132].
  1. VLM Visceral larva migrans, OT Ocular toxocariasis, CT Covert or common toxocariasis, NT Neurotoxocariasis, DUSN Diffuse unilateral subacute neuroretinitis, DSN Distal symmetric sensory neuropathy