Reactive arthritis associated with Strongyloides stercoralis: Report of an uncommon relation.

Sir,

Reactive arthritis (ReA) is a group of diverse, nonseptic, and inflammatory arthropathies where extraarticular infections with certain organisms precede joint and extraarticular manifestations.[1] Often, the condition manifests as an asymmetrical inflammatory oligoarthritis in the lower limbs and apart from the joints, can affect the eyes, urinary tract, mouth, colon, and heart.[123] According to population-based studies, the annual incidence of ReA is 0.6–27/100,000 and the prevalence is estimated to be 30–40 per 100,000 adults.[34] The HLA-B27 genetic marker is commonly found in blood, in approximately 70% of patients.[35] Pathogens conventionally implicated as triggers for ReA are the “arthritogenic bacteria” such as Chlamydia, Yersinia, Salmonella, Shigella, Campylobacter, Ureaplasma urealyticum, and Clostridium difficile which usually cause enteric or genitourinary infections.[24567] ReA due to parasites have been reported uncommonly. We report a case of ReA due to Strongyloides stercoralis infestation in an HLA-B27 positive child who responded to specific antiparasitic treatment.

An 11-year-old girl was admitted with a 20-day history of pain and swelling in both knees, a 15-day history of pain in the right hip and left second toe, and redness, watering, and diminution of vision of both eyes for 10 days. She also complained of recent onset fever and cough of 3 days duration. The fever was of moderate grade, intermittent in nature, and associated with chills. The cough was productive in nature. The child was immunised for age as per the Universal Immunization Programme. There was no history of contact with tuberculosis and no urinary or bowel complaints. Before her admission at our hospital, she had consulted two different hospitals and received various medications for her eye and joint symptoms, but without any relief. Further probing revealed that she was a student, assisted her father in farming and would often go barefoot to the fields.

On examination, she was febrile (oral temperature 38.2°C), had a pulse rate of 104/min, respiratory rate 20/min, and blood pressure 104/71. She was underweight (23 kg, −3.04 z score) for her age but height was within normal ranges. Multiple hyperkeratotic, hyperpigmented papules, and plaques (keratoderma blenorrhagicum) covered by dark gray crusts were noted on the back [Figure 1a]. Examination of various joints showed both knees were warm, swollen, and tender. Movements of right hip were restricted and painful. Ocular examination revealed crescent-shaped peripheral corneal thinning with superficial vascularisation and infiltrates in the right eye, suggesting a diagnosis of peripheral ulcerative keratitis [Figure 1b]. Left eye showed a small area of peripheral corneal thinning. Visual acuity was reduced to perception of hand movements in right eye and 6/60 in left eye. Rest of the ophthalmic examination including fundus was unremarkable.

Figure 1

Patient of reactive arthritis with (a) keratoderma blenorrhagicum on back, and (b) peripheral ulcerative keratitis in right eye

Laboratory investigations showed significant eosinophilia (absolute eosinophil count-4447/mm3). Serum electrolytes, renal and liver function tests were within normal limits. She tested negative for rheumatoid factor, antinuclear antibodies, and antistreptolysin O antibodies. HLA B-27 was positive (flow cytometry). Microbiological investigations revealed a normal urine microscopy and a sterile blood and urine culture. Gram stain and cultures of synovial fluid aspirated from the left knee were negative. Stool culture was negative for Salmonella, Shigella, and C. difficile. A stool microscopic, wet-mount examination, however, showed motile, rhabditiform larvae of S. stercoralis [Figure 2]. The patient was immediately started on oral ivermectin along with nonsteroidal anti-inflammatory drugs and prednisolone eye drops. The skin lesions were treated with application of topical steroids. She responded briskly with decrease of joint pain, swelling, and improved range of motion within 2 weeks of initiating the treatment. Vision in the left eye improved to 6/24. The patient was discharged on the 15th day of admission with advice to follow-up in the outpatient department after 1 month.

Figure 2

Wet-mount microscopy of stool showing rhabditiform larvae of Strongyloides stercoralis, ×400

S. stercoralis is a soil-transmitted nematode with a worldwide distribution but is more common in tropical and subtropical regions. Worldwide, over 100 million people are infected with this parasite.[8] The vast majority of infections in endemic areas are asymptomatic. However, serious medical conditions such as hyperinfection syndrome or disseminated strongyloidiasis may develop rapidly in immunocompromised hosts.[8]

Arthritis is a rare feature of a parasitic infection including Strongyloides and is probably immune-complex-mediated. In 2003, van Kuijk et al[9] described nine earlier reports, involving patients with either oligo – or polyarthritis in association with intestinal Strongyloides infection, apart from their own. To the best of our knowledge, only four additional cases have been reported after that till date.[10111213] The joints usually involved have been polyarthritis of the shoulders, wrists, hand joints, knees, ankles, and feet.[9101112] Unusual sites, such as involvement of sacroiliac joint[14] and sternoclavicular joint[13] has been reported occasionally. Other presentations such as skin rash and uveitis are also observed at times.[101415] Rashes are most common on the palms and soles but may occur elsewhere as well, such as the extremities and abdomen.[10] Ophthalmic manifestations usually occur in the form of conjunctivitis in two-thirds of children with ReA, but keratitis is uncommon.[1] Our patient had skin lesions mainly on the back and ophthalmologic manifestations in the form of peripheral ulcerative keratitis, uncommon findings in children with ReA. Association with HLA-B27 in conjunction with ReA due to S. stercoralis infestation has been noted in one previous case report.[12] Of note, treatment with antihelminthic drugs (thiabendazole, ivermectin, or albendazole) usually results in prompt improvement and early resolution of symptoms[14] which was also observed in our patient.

Apart from Strongyloides, ReA has occasionally been described in patients with other helminthic infections such as Wuchereria bancrofti,[16] Dirofilaria,[17] Ascaris lumbricoides,[18] Anisakis,[19] Taenia saginata,[20] as well as Schistosoma haematobium, Enterobius vermicularis, Echinococcus, and Ancylostoma spp.[14] Intestinal infection with protozoan parasites such as Cryptosporidium, Giardia, and Entamoeba associated with ReA have been reported less frequently.[1420] It is likely that Strongyloides infection in the present case was acquired due to penetration of filariform larvae, while the patient worked in the fields without shoes from time to time.

ReA is a clinical diagnosis, since there are no definitive diagnostic laboratory tests or radiographic findings associated with the condition. The diagnosis should be entertained in any patient with an acute inflammatory, asymmetric arthritis in conjunction with ocular, or skin lesions. Considering the wide prevalence of Strongyloides infection throughout the world, the number of cases of ReA due to this organism is probably underestimated. Clinicians and microbiologists need to be aware of this clinical condition. Infection with S. stercoralis should be kept as a differential diagnosis of pathogens associated with ReA, to avoid inadvertent and inappropriate administration of corticosteroids in such cases, which can lead to fatal multiorganic dissemination of the parasite.

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