A serological analysis of viral and bacterial infections associated with neuromyelitis optica.

To evaluate the role of infections in the development of neuromyelitis optica (NMO), 19 patients positive for anti-aquaporin-4 antibody were screened for 24 viral and bacterial infections. Serological evidence of recent viral infection was found in 7 of 15 patients screened during the acute phase of the neurologic illness, which was a significantly more frequent rate of infection than seen in the control group of 33 patients with neurodegenerative, metabolic, or vertebral diseases (47% versus 15%). Mumps virus and human herpes viruses were the frequent causal agents, although there was no statistical difference in frequency between the two groups. Most patients with identified recent infection had monophasic or recurrent myelitis without evidence of optic nerve involvement and small number of total clinical relapses. Disease history tended to be shorter in patients with identified recent infection than those without, and an expanded long spinal cord lesion in magnetic resonance imaging was rarely found in patients with identified recent infection, although statistical significance could not be shown. These findings indicate that, not single, but various viral infections, can be associated with the development of NMO during the early stages of the illness, although the exact pathogenesis of NMO has yet to be clarified.