Increased incidence of Guillain-Barré syndrome corresponded closely with patterns of Zika virus disease incidence in Central and South America from April 2015 through March 2016, according to results from a new temporal and graphic analysis.
The findings show Guillain-Barré syndrome (GBS) cases increasing from 100% to nearly 900% above previously recorded baseline rates during periods of Zika virus transmission in El Salvador, the Dominican Republic, Colombia, Honduras, Suriname, Venezuela, and the Brazilian state of Bahia (N Engl J Med. 2016 Aug 31. doi: 10.1056/NEJMc1609015).
The analysis of the yearlong period also revealed that declines in GBS incidence accompanied declines in Zika virus disease when and where transmission began to wane. The researchers, led by Marcos A. Espinal, MD, DrPH, of the Pan American Health Organization in Washington, did not find significant associations between co-circulation of dengue virus and GBS incidence. The study, which looked at 164,237 confirmed and suspected cases of Zika virus disease and 1,474 cases of GBS, found a 75% higher Zika virus disease incidence rate in women, which Dr. Espinal and colleagues said might be attributable to differences in health care–seeking behavior. GBS incidence, meanwhile, was 28% higher among males. The higher rate of GBS in men, the authors said, was consistent with findings from previous epidemiological studies of GBS.
While the new results did not show that Zika virus causes GBS, Dr. Espinal and colleagues wrote, they argued that they were indicative of a strong association, adding that GBS “could serve as a sentinel for Zika virus disease and other neurological disorders linked to Zika virus,” including microcephaly.
Most of the study authors worked for the Pan American Health Organization or for national health agencies in the data-contributing countries. None declared conflicts of interest.