Zika Virus May Be Linked to Another Brain Disease

Brazilian researchers report cases of encephalomyelitis

The Zika virus may be associated with an autoimmune disorder that attacks the brain’s myelin similar to multiple sclerosis, according to a new study presented at the American Academy of Neurology’s 68th annual meeting in Vancouver, Canada.

“Though our study is small, it may provide evidence that in this case the virus has different effects on the brain than those identified in current studies,” said lead investigator Maria Lucia Brito Ferreira, MD, of the Restoration Hospital in Recife, Brazil. “Much more research will need to be done to explore whether there is a causal link between Zika and these brain problems.”

For the study, researchers followed people who came to the hospital from December 2014 to June 2015 with symptoms compatible with arboviruses, the family of viruses that includes Zika, dengue, and chikungunya. Six people developed neurological symptoms that were consistent with autoimmune disorders and underwent examinations and blood tests.

All of the people came to the hospital with fever followed by a rash. Some also had severe itching, muscle and joint pain, and red eyes. The neurological symptoms started immediately for some patients and up to 15 days later for others.

Of the six patients with neurological symptoms, two developed acute disseminated encephalomyelitis (ADEM)––swelling of the brain and spinal cord that can affect the myelin coating on nerve fibers, Ferreira reported. In both cases, brain scans showed signs of damage to the brain’s white matter. Unlike multiple sclerosis, ADEM usually consists of a single attack, from which most patients recover within six months. In some cases, the disease can reoccur. Four of the six patients with neurological involvement developed Guillain-Barré syndrome (GBS), a disease involving myelin of the peripheral nervous system. Cases of GBS have been reported in association with Zika virus infection.

When the six patients were discharged from the hospital, five still had problems with motor functioning, Ferreira said. One person had vision problems, and one had problems with memory and thinking skills. Tests showed that all of the patients had Zika virus infection. Tests for dengue and chikungunya were negative.

“This doesn’t mean that all people infected with Zika will experience these brain problems. Of those who have nervous system problems, most do not have brain symptoms,” Ferreira said. “However, our study may shed light on possible lingering effects the virus may be associated with in the brain.”

James Sejvar, MD, of the Centers for Disease Control and Prevention, commented: “At present, it does not seem that ADEM cases are occurring at a similarly high incidence as the GBS cases, but these findings from Brazil suggest that clinicians should be vigilant for the possible occurrence of ADEM and other immune-mediated illnesses of the central nervous system. 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.”

Source: American Academy of Neurology; April 10, 2016