Visceral Toxocariasis Presenting as Systemic-Onset Juvenile Idiopathic Arthritis

Abstract

An 8-year-old boy presented with intermittent fever, abdominal pain and joint pain for 1 month. On examination, he had pallor, generalized lymphadenopathy, hepatomegaly and arthritis. Investigations revealed anemia, leucocytosis, hypereosinophilia and hypergammaglobulinemia, with an elevation of inflammatory markers. Initially, suspected as systemic-onset juvenile idiopathic arthritis, and on further probing, the child had geophagy and contact with dogs in the household. Ultrasonography of the abdomen showed multiple cystic lesions, and serology for Toxocara canis was positive; hence the child was diagnosed with visceral toxocariasis and managed with albendazole therapy.

toxocariasis, hypereosinophilia, hypergammaglobulinemia

CASE REPORT

An 8-year-old boy presented with a history of low-grade, intermittent fever for 1 month. The child also complained of vague abdominal pain, joint pain, joint swelling and difficulty in walking. On examination, he had pallor, generalized lymphadenopathy, firm hepatomegaly with tender swelling of bilateral knee joints. Investigations were suggestive of anemia (7.5 g/dl), leucocytosis (50.25 × 103/µl), eosinophilia (32.74 × 103/µl) and thrombocytosis (586 × 103/µl) with no atypical cells or blasts on peripheral smear. Serum total protein was elevated (11.1 g/dl) with normal serum albumin (3.3 g/dl). Serum IgE antibodies (1160 IU/ml), erythrocyte sedimentation rate (ESR) (100 mm/h) and high sensitivity C-reactive protein (hs-CRP) (20 mg/dl) were also elevated. Because of prolonged fever, arthritis, generalized lymphadenopathy, hepatomegaly, leukocytosis, thrombocytosis, hypergammaglobulinemia and elevated inflammatory markers (ESR, hs-CRP), the possibility of systemic-onset juvenile idiopathic arthritis (sJIA) was considered initially. Rheumatoid factor and antinuclear antibodies were negative. Evaluation for tuberculosis and syphilis were also negative. On further probing, there was a history of pica and passing worms in stools for 1 year. The child was also playing with dogs in the household for the past 3 years. Ultrasonography of the abdomen revealed an enlarged liver (11.5 cm) with multiple tiny focal hypoechoic lesions involving bilateral lobes of the liver, with the largest measuring 7 mm × 5 mm in size. No ova/cyst was detected from the stool sample. Due to cystic lesions in the liver with hypereosinophilia, we suspected toxocariasis. Serology for IgG Toxocara canis was positive. After oral albendazole therapy, the child improved clinically, and all laboratory and radiological parameters normalized.

Toxocariasis is an infectious parasitic disease that occurs due to soil ingestion containing larvas or eggs of T.canis and Toxocara catis. It is commonly seen in children less than 12 years, mostly in rural areas [1]. It spreads through contact with pet animals, especially dogs and geophagy. Toxocariasis in children characteristically presents with fever, cough, abdominal pain, hepatomegaly, rarely as pneumonia, meningitis, myositis, eczema and arthritis [2]. The clinical spectrum of toxocariasis varies from asymptomatic cases to visceral larva migrans, neurological and ocular toxocariasis [3]. The immediate hypersensitivity reaction to the dying and dead larva causes eosinophilia and elevated IgE. At the same time, prolonged antigenic stimulation induce granuloma formation and elevation of immunoglobulins IgG subclasses, which leads to hypergammaglobulinemia [2, 4]. Autoinflammatory diseases like lupus, rheumatoid arthritis, mixed connective tissue disorders, rarely in acute bacterial infections, and viral infections also produce hypergammaglobulinemia in children [5]. Diagnosis of toxocariasis is confirmed by ELISA testing, which detects IgG antibodies to Toxocara excretory–secretory antigens. Treatment is albendazole 15 mg/kg for 5 days [6].

Juvenile idiopathic arthritis is the most common chronic rheumatic disorder affecting children less than 16 years and is divided into several subgroups including sJIA which is seen in 10–20% of cases [7]. The diagnosis of sJIA requires the presence of arthritis accompanied or preceded by a fever of at least 2 weeks’ duration, plus one of the following: characteristic rash, generalized symmetrical lymphadenopathy, hepatomegaly, splenomegaly or serositis as per the International League Against Rheumatism criteria [8]. Overlapping clinical and laboratory findings made us suspect sJIA in our case as it is much more common than toxocariasis.

To conclude, in a child with unexplained prolonged fever, hypereosinophilia and hypergammaglobulinemia, the treating pediatricians should be aware of the possibility of toxocariasis, especially in the setting of pets in the household and rural areas.

Informed consent: Written informed consent was obtained from the parents for the case report.