CONCURRENT FOCAL BRUCELLOSIS AND RHEUMATOID ARTHRITIS IN A SCHOOLGIRL

Abstract

Intro: Brucellosis is a zoonosis acquired from domesticated farm animals. In Sri Lanka, seroprevalence studies have shown asymptomatic human infection but indigenously-acquired human brucellosis has not been reported. Methods: A 16-year-old schoolgirl from Polonnaruwa was admitted with symmetrical pain and swelling in peripheral large and small joints and right hip pain with reduced range of movement. She consumed raw cow's milk frequently and gave no previous or current contact history of tuberculosis. She had never traveled outside Sri Lanka. Findings: Her serology for B. abortus by standard agglutination test was positive, with a titre of 1:1280. Magnetic resonance imaging (MRI) showed right sided sacroiliitis. She was commenced on gentamicin (2 weeks), rifampicin and doxycycline (6 weeks). After 2 weeks, hip tenderness settled completely but her peripheral joint symptoms persisted. A diagnosis of concurrent ‘definitive rheumatoid arthritis (RA)’ was made, based on involvement of >10 joints, positive Rheumatoid Factor (145 IU/mL) and positive anti-cyclic citrullinated protein antibodies (414.5 U/mL). She was commenced on methotrexate, with significant improvement. Repeat MRI showed complete resolution of sacroiliitis and Brucella serology became undetectable after 4 months. Discussion: This patient presented with focal manifestations of brucellosis and concurrent RA. Her diagnosis of brucellosis was nearly missed due to the concurrent features of RA. A multidisciplinary approach is critical in such cases for early diagnosis of both conditions. Sacroiliitis is the commonest osteoarticular manifestation in brucellosis and tends to be commoner in young patients. The MRI is useful to assess the extent of osteoarticular brucellosis and in follow-up. Her sacroiliitis recovered clinically and radiologically following specific therapy. Concurrent RA subsequently improved on methotrexate. Conclusion: This highlights the importance of considering brucellosis in patients with rheumatological syndromes from an epidemiological background. To our knowledge, this is the first laboratory-confirmed case of human brucellosis acquired in Sri Lanka and with concurrent RA globally.