Further evidence links Zika, Guillain-Barre syndrome

Evidence of Zika virus found in Colombian patients with Guillain-Barre syndrome supports the theory that Zika virus infection and Guillain-Barre syndrome are related and could occur parainfectiously, a study showed.

“Study provides virologic evidence of (Zika virus) infection in patients with Guillain-Barre syndrome,” wrote the Hospital Universitario del Valle in Valle del Cauca, Colombia.

The Zika study looked at 68 patients with Guillain-Barre syndrome, all of whom received their diagnoses at one of six university-based health care centers across Colombia between January and March 2016.

The median age was 47 years, 56% were male, and 90% were of mixed race. All 68 patients were evaluated clinically for Guillain-Barre syndrome and underwent neurologic evaluation as well.

Of the 68 subjects, 42 also underwent laboratory testing to find Zika virus RNA in blood, cerebrospinal fluid, or urine, via reverse-transcriptase polymerase chain reaction testing.

The results indicated that 66 of 68 subjects (97%) had symptoms consistent with a Zika virus infection prior to the onset of Guillain-Barre syndrome.

The median number of data between the onset of Zika-like symptoms and the onset of Guillain-Barre syndrome in patients was found to be 7 days (interquartile range, 3-10 days).

Seventeen of the 42 patients (40%) who underwent laboratory testing tested positive for Zika virus RNA in their sample, with 16 of those 17 positive tests coming from urine samples.

In addition, 18 of the 42 laboratory-tested subjected had “clinical and immunologic findings (that) supported” a Zika virus infection, the Zika study investigators reported.

“The onset of the Guillain-Barre 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 post infectious mechanisms may be present in (Zika virus)-related Guillain-Barre syndrome,” the report that results of a prospective study of 68 Colombian patients who had a syndrome consistent with the Guillain-Barre syndrome, 66 of whom had previously had symptoms of Zika virus (ZIKV) infection.

Major strengths of this study include the documentation of a temporal relationship between the Guillain-Barre syndrome and ZIKV infection (marked by a substantial increase in the incidence of the Guillain-Barre syndrome after the introduction of ZIKV, from 20 to 90 cases per month throughout Colombia), the criteria applied for the diagnosis of the Guillain-Barre syndrome, and the molecular and serologic flavivirus data from analyses of serum, cerebrospinal fluid and urine.

The difficulties in diagnosing ZIKV infection are borne out this study, as only 17 patients had definitive laboratory evidence of recent ZIKV infection. Of these 17 patients, only 14 had electrophysiologic data consistent with the Guillain-Barre syndrome and therefore could have met Brighton level 1 diagnostic criteria for the syndrome. Among the 25 ZIKV polymerase chain reactions – negative patients, dengue virus (DENV) lgG antibodies were present in the cerebrospinal fluid of 12 patients and in the serum of 10 patients, and serum DENV lgM test results were positive in 1. These data raise the possibility of primary DENV infection and false-positive ZIKV serologic test results from cross-reactivity.

Overall, the study supports the association between ZIKV and the Guillain-Barre syndrome, although confirmation in another cohort would strengthen this assertion. Although high rates of seropositivity may prove protective against further waves of ZIKV-related Guillain-Barre syndrome in Central and South America,the ZIKV pandemic is just beginning in North America and Africa, and an increase in the incidence of the Guillan-Barre syndrome may follow.