Zika is tied to second adult brain disease, deepening fears of virus's unknown dangers

Maria Lucia Brito Ferreira, a doctor at Restoration Hospital in Recife, Brazil, wrote in an abstract that will be presented at the American Academy of Neurology's 68th Annual Meeting in Vancouver April 15-21 that two of the patients experienced swelling of the brain and spinal cord that involved the myelin, or coating, around nerve fibers. They were diagnosed as having acute disseminated encephalomyelitis, or ADEM, which is so similar to multiple sclerosis that many practitioners have trouble distinguishing between the two.

The brief but intense attack often follows viral or bacterial infections. The U.S. National Institute of Neurological Disorders and Stroke says that the long-term prognosis is "generally favorable." However, some patients may have mild to moderate lifelong impairment, including cognitive difficulties or loss of vision. In rare cases, the condition can be fatal.

Ferreira was cautious in interpreting her findings, emphasizing that most people who experience nervous system problems with Zika do not have brain symptoms and that a definitive causal link between Zika and the ADEM has not been made.

"However, our study may shed light on possible lingering effects the virus may be associated with in the brain," she said.

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Health officials have previously expressed concern about Zika's association with a different neurological condition known as Guillain-Barré syndrome, in which the immune system attacks the nerves and can start as weakness or tingling and can lead to paralysis.

James Sejvar, a researcher with the U.S. Centers for Disease Control and Prevention in Atlanta, said clinicians should be "vigilant" for ADEM and other "immune-mediated illnesses of the central nervous system" even though at present it does not appear that ADEM cases are occurring at the same rates as Guillain-Barré.

"Of course, the remaining question is 'why' - why does Zika virus appear to have this strong association with GBS and potentially other immune/inflammatory diseases of the nervous system? Hopefully, ongoing investigations of Zika virus and immune-mediated neurologic disease will shed additional light on this important question," he said.

Ferreira's research involved tracking people seen December 2014 to June 2015 who came to the hospital with fever followed by a rash. She reported that the onset of neurologic symptoms was immediate for some but that for others they occurred up to 15 days later.

Six people in the group experienced neurologic issues, and all were confirmed to have Zika but no other related viruses. Four had Guillain-Barré syndrome, and two had ADEM.