Researchers investigating a 2015 outbreak of Guillain-Barré syndrome in Brazil found that it was much more prevalent than expected — and saw signs that it may be associated with Zika virus.
Results of the investigation into an apparent increase of Guillain-Barré syndrome (GBS) cases in the Salvador metropolitan area between April and July 2015 were presented at the CDC’s Epidemic Intelligence Service Conference in Atlanta. During that same period, the region had high rates of Zika virus transmission.
Ashley R. Styczynski
“We found that the incidence of GBS was nine to 19 times higher than expected during the outbreak period,” Ashley R. Styczynski, MD, MPH, Epidemic Intelligence Service officer at the CDC, told Infectious Disease News. “Additionally, a majority of the patients with GBS reported an acute illness prior to onset of their neurologic symptoms that was characterized by rash, conjunctivitis, and retro-orbital pain, symptoms commonly associated with Zika virus infections.”
Reports of GBS — an uncommon condition in which a patient’s immune system damages nerve cells, leading to muscle weakness and, occasionally, paralysis — simultaneously increased in certain regions of Brazil where Zika virus rapidly spread. Overlap was observed in the geographic regions where each sickness was reported most often, according to Styczynski and colleagues.
The CDC has been unable to positively confirm an association between GBS and Zika virus, although the agency has said the sickness is “very likely triggered by Zika in a small proportion of infections.”
“Though confirmatory laboratory testing is pending,” Styczynski said, “our epidemiologic data strongly suggests that GBS may be associated with Zika virus.”
Zika’s potential link to other conditions also is being explored as the virus’ continued spread in the Americas fuels more research.
Recently, researchers at the American Academy of Neurology Annual Meeting reported 151 cases of neurological manifestations in patients treated at a hospital in Brazil between December 2014 and June 2015 for symptoms compatible with arboviruses. Of six patients with Zika who developed neurologic problems, four were diagnosed with GBS, and two were diagnosed with acute disseminated encephalomyelitis.
“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,” study researcher Maria Lucia Brito Ferreira, MD, said in a press release. “Much more will need to be done to explore whether there is a causal link between Zika and brain problems.” – by Gerard Gallagher
Ferreira, MLB, et al. Abstract 9157. Presented at: American Academy of Neurology Annual Meeting; April 15-21, 2016; Vancouver, British Columbia.
Styczynski AR, et al. Guillain-Barré syndrome outbreak – Bahia State, Brazil, 2015. Presented at: Epidemic Intelligence Service Conference; May 2-5, 2016; Atlanta.
Disclosure: The researchers report no relevant financial disclosures.