Evidence of Zika virus found in Colombian patients with Guillain-Barré syndrome supports the theory that Zika virus infection and Guillain-Barré syndrome are related and could occur parainfectiously, according to a study published in the New England Journal of Medicine.

“Our study provides virologic evidence of [Zika virus] infection in patients with Guillain-Barré syndrome,” wrote Beatriz Parra, PhD, of the Hospital Universitario del Valle in Valle del Cauca, Colombia, and her coauthors ( N Engl J Med. 2016 Oct 5. doi: 10.1056/NEJMoa1605564 ).

The study looked at 68 patients with Guillain-Barré syndrome, all of whom received their diagnoses at one of six university-based health care centers across Colombia between January and March 2016. Median age was 47 years, 56% were male and 90% of mixed race. All 68 patients were evaluated clinically for Guillain-Barré syndrome and underwent neurologic evaluation as well. Of the 68 subjects, 42 also underwent laboratory testing to find Zika virus RNA in either blood, cerebrospinal fluid, or urine, via reverse-transcriptase polymerase chain reaction (RT-PCR) testing.

Results indicated that 66 (97%) of subjects had symptoms consistent with a Zika virus infection prior to the onset of Guillain-Barré syndrome. The median number of days between onset of Zika-like symptoms and the onset of Guillain-Barré syndrome was found to be 7 days (interquartile range, 3-10 days). Seventeen (40%) of the 42 patients who underwent laboratory testing tested positive for Zika virus RNA in their sample, with 16 of those 17 positive tests coming from urine samples. Additionally, 18 of the 42 laboratory-tested subjects had “clinical and immunologic findings [that] supported” a Zika virus infection.

“The onset of the Guillain-Barré syndrome can parallel the onset of systemic manifestations of [Zika virus] infection, indicating a so-called parainfectious onset, which suggests that factors different from the known postinfectious mechanisms may be present in [Zika virus]–related Guillain-Barré syndrome,” the authors explained, adding that 20 (48%) of the 42 laboratory-tested subjects had a parainfectious onset.

“RT-PCR testing of urine is a valuable diagnostic tool for the identification of [Zika virus] infection in patients with Guillain-Barré syndrome,” Dr. Parra and her coauthors concluded.

The study was funded by the Bart McLean Fund for Neuroimmunology Research, Johns Hopkins Project Restore, and the Universidad del Valle. Dr. Parra reported no relevant financial disclosures.