Infectious agents associated with myopathies.

Several infectious agents can cause chronic or acute myopathy. Most current investigations into possible infectious causes of the idiopathic inflammatory myopathies have focused on retroviruses, including HIV and human T-cell leukemia-lymphoma virus type I. In both cases, viruses likely do not directly infect muscle fibers but instead induce an immunologically mediated myositis. Other interest has focused on enteroviruses as potential etiologic agents of idiopathic inflammatory myopathy, but their relationship to human myositis is less clear. In addition to chronic muscle disease, several infectious agents can cause acute myositis, including pyomyositis, which is being recognized in temperate climates with increasing frequency, and rhabdomyolysis.