Microsporidia involved in myositis:
(1) Brachiola algerae (formerly genus Nosema)
(2) Brachiola vesicularum
(3) Pleistophora ronneafiei
(4) Trachipleistophora hominis
Risk factors that may contribute to susceptibility of infection:
(1) HIV infection
(2) infliximab therapy
(3) diabetes
(4) corticosteroid therapy
(5) organ transplantation
Clinical and laboratory features:
(1) fever
(2) muscle pain
(3) fatigue and weakness
(4) elevated serum creatinine kinase
The cause is usually not expected prior to muscle biopsy. It also may not be a diagnosis that the pathologist considers. Immunoperoxidase stains can help to identify the organism.
Diagnosis also involves exclusion of other causes of myositis.
