Abstract
The insect microsporidian Anncaliia algerae was first described in 2004 as a cause of fatal myositis in an immunosuppressed person from Pennsylvania, USA. Two cases were subsequently reported, and we detail 2 additional cases, including the only nonfatal case. We reviewed all 5 case histories with respect to clinical characteristics, diagnosis, and management and summarized organism life cycle and epidemiology. Before infection, all case-patients were using immunosuppressive medications for rheumatoid arthritis or solid-organ transplantation. Four of the 5 case-patients were from Australia. All diagnoses were confirmed by skeletal muscle biopsy; however, peripheral nerves and other tissues may be infected. The surviving patient received albendazole and had a reduction of immunosuppressive medications and measures to prevent complications. Although insects are the natural hosts for A. algerae, human contact with water contaminated by spores may be a mode of transmission. A. algerae has emerged as a cause of myositis, particularly in coastal Australia.
Highlights
Background illnessRA RA, T2DMLung Tx, T1DM, CD Lung Tx, kidney TxImmunosuppressionMTX, CS, LEF, MTXMTX, CS, LEF, IFX AZ, TAC, MMF, CS TAC, MMF, CS ETN Fever Yes Fatigue Weight loss
We describe 2 additional cases of A. algerae myositis in patients with histories of rheumatoid arthritis, including 1 who survived
The urinary myoglobin was negative in case-patient A, and urinary sediment staining for microsporidia was either not performed or not documented in any of the case-patients
Summary
All case-patients were using immunosuppressive medications for rheumatoid arthritis or solid-organ transplantation. A. algerae has caused severe myositis in patients taking immunosuppressive medication for rheumatoid arthritis or solid-organ transplantation [3,5,8]. We describe 2 additional cases of A. algerae myositis in patients with histories of rheumatoid arthritis, including 1 who survived. Australia, sought care at hospital for an 8-week history of watery diarrhea; weight loss; and increasing arthralgias, fatigue, lethargy, and generalized myalgias. He had rheumatoid factor–positive rheumatoid arthritis that was diagnosed when he was in his early twenties, with fluctuating joint disease, but no extra-articular involvement. Albendazole (400 mg 2×/d), sulfadiazine (1 g 4×/d) and pyrimethamine (50 mg/d)
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