Washington, Apr 11: The Zika virus, which is linked with incomplete foetal brain development and temporary paralysis, may also be associated with a range of other brain disorders, a new study has warned.
The virus may be associated with an autoimmune disorder that attacks the brain's myelin similar to multiple sclerosis (MS), researchers said.
"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 Maria Lucia Brito Ferreira, from the Restoration Hospital in Brazil.
"Much more research will need to be done to explore whether there is a causal link between Zika and these brain problems," Ferreira said.
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 then developed neurologic symptoms that were consistent with autoimmune disorders and underwent exams and blood tests.
The researchers saw 151 cases with neurological manifestations during a period of 2014 to 2015. 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 neurologic symptoms started right away for some people and up to 15 days later for others. Of the six people who had neurologic problems, two of the people developed acute disseminated encephalomyelitis (ADEM), an attack of swelling of the brain and spinal cord that attacks the myelin, which is the coating around nerve fibres.
In both cases, brain scans showed signs of damage to the brain's white matter. Unlike MS, acute disseminated encephalomyelitis usually consists of a single attack that most people recover from within six months.
In some cases, the disease can reoccur. Four of the people developed Guillain-Barre syndrome (GBS), which involves myelin of the peripheral nervous system and has a previously reported association with the Zika virus.
When they were discharged from the hospital, five of the six people still had problems with motor functioning. One person had vision problems and one had problems with memory and thinking skills.
Tests showed that the participants all had Zika virus. 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," said Ferreira.
"However, our study may shed light on possible lingering effects the virus may be associated with in the brain," she said.