An unusual case of poliarthritis

A 55 years old man, living in rural area of Italy, was addressed to our clinic because of progressive multi-joint involvement and deterioration of the general conditions over the last 16 months despite the prolonged use of steroids and empiric therapy. His medical history was poor: a partial gastrectomy for peptic ulcer when he was 30 years old and no further clinically relevant conditions up to 5 months earlier, when he was first admitted in hospital for worsening of general conditions, pain and swelling of the right sternoclavicular joint, abdominal pain, vomiting and asthenia. The patient was discharged without a definitive diagnosis, and continued therapy with steroids. In the following months he develops a severe polyarthritis, cough, fever, progressive severe weight loss, so he was hospitalized in our clinic for further medical examination. Physical examination revealed swelling of the right sterno clavicular joint with tenderness during palpation, and multiple joint involvement (ankles, wrists and metacarpophalangeal of the right hand). Palpation of abdomen elicited pain in the epigastrium. Chest examination revealed moderate broncostenosis. A weakness of right leg was also observed. Laboratory showed high Eritrocyte Sedimentation Rate (112 mm/1st hour), high C-reactive protein (8.5 mg/dl), low haemoglobin (9.8 g/dl), high leucocyte count with normal granulocyte distribution, thrombocytosis, low proteins (3.1 g/dl) with low albumin (1.7 mg/dl), low serum iron (22 μg/dl; normal values: 40-160), low transferrin (35 mg/dl; 200-360), high ferritin (357 ng/ml; 5-232), whereas vitamin-B12 and folic acid levels were normal. For suspected inflammatory bowel disease fecal occult blood test and calprotectin assay were performed and were not diagnostic. It was performed a parasitological examination of stools on multiple assays, and they were negative. To exclude malignancy a sampling was performed for cancer markers, that were negative. Anti-cyclic citrullinated peptide antibodies, rheumatoid factor, complement, immunoglobulin, antibodies for celiac disease and antinuclear antibodies tested were all negative. A workup for infectious agents including serology for Parvovirus B-19, Brucella, Borrelia, Salmonella, HCV, HBV, CMV, HIV, HZV, HSV, EBV, HTLV-1 was tested and was positive for HCV. Electroneurographic examination was performed to investigate the weakness of right leg revealing a mild neuropathy. Magnetic resonance imaging of the brain and spinal was not diagnostic. To investigate occult malignancy, chest and abdomen computed tomography were performed revealing a thickening of right bronchial and of colonic mucosa. To further investigate, also suspecting an intestinal lymphoma, the patient underwent to a colonoscopy that revealed mucosal edema and erythema, so multiple biopsies were performed. To exclude a bone cancer or repetitive lesions a scintigraphic skeletal examination was performed that showed an increased uptake of the right sternoclavicular joint and left shoulder. Finally, the istopathologic examination of the bowel biopsies described massive infestation of Strongyloides stercoralis. Albendazolo 400 mg three times/day was consequently started. Strongyloides stercoralis is an intestinal nematode; humans are generally infected transcutaneously, although infection has also been experimentally induced by oral administration of water contaminated with filariform larvae. The diagnosis could be difficult because the parasite load is low and the larval output is irregular. Albendazole may stimulate the excretion of larvae into stool allowing subsequent identification in the sample. After two days of therapy the parasite was detected in stool and sputum assays and after 15 days of therapy the parasitological exams of the stool did not identify parasites, articolar pain and swelling resolved and laboratory values were normalized. The patient has started to eat regularly and regain weight; laboratory markers were then normalized. Patients under corticosteroid therapy have higher risk of being infected by Strongyloides stercoralis probably through its inhibitory action on eosinophils. Additionally, steroid may have a direct effect on the parasites, accelerating the transformation of rhabditiform to invasive filariform larvae or rejuvenating latent adult females thus facilitating their spreading. In uncommon feature of arthritis, some rare parasitosis have to be excluded before treatment with steroids avoiding a potentially lethal infection