The Zika virus, which is associated with incomplete foetal brain development and temporary paralysis, might also be linked with a range of other brain disorders, according to a new study.
Zika has already been associated with the autoimmune disorder Guillain-Barre syndrome, which attacks peripheral nerves outside the brain and spinal cord, causing temporary paralysis. Now, Brazilian scientists have uncovered a new brain disorder linked with Zika infections in adults: an autoimmune syndrome called acute disseminated encephalomyelitis (ADEM) that attacks the spinal cord and brain.
There is a strong scientific consensus that, in addition to Guillain-Barre, Zika can cause the birth defect microcephaly, though conclusive proof might take months or years. Microcephaly is defined by unusually small heads that can result in developmental problems, according to the World Health Organization (WHO).
Brazil has confirmed over 940 cases to be related to Zika infections in the mothers. The country is investigating nearly 4,300 additional suspected cases of microcephaly.
Apart from autoimmune disease, some researchers have also reported patients with Zika infections developing encephalitis and myelitis – nerve disorders usually caused by direct infections in nerve cells.
Generally, ADEM occurs in the aftermath of an infection, causing intense swelling in the spinal cord and brain that damages myelin, the white protective coating surrounding nerve fibers.
Dr. Maria Lucia Brito, a neurologist at Restoration Hospital in Recife, Brazil, presented her findings at the American Academy of Neurology meeting in Vancouver.
The study involved 151 patients who visited her hospital between December 2014 and June 2015. All the patients had been infected with arboviruses, the family of viruses that includes Zika, chikungunya and dengue.
6 of these patients developed symptoms consistent with autoimmune disorders. Of the 6, four had Guillain-Barre and 2 had ADEM. In both ADEM cases, brain scans demonstrated damage to white matter.
All the 6 patients tested positive for Zika, and all had lingering effects after being discharged from the hospital, with 5 patients reporting motor dysfunction, one with cognitive decline and one with vision problems.