Growing evidence suggests that there is a causal association between Zika virus infection and Guillain-Barré syndrome (GBS), according to the results of a recent case-control study conducted in Puerto Rico and published in JAMA.
Potential case patients with a clinical suspicion of GBS and onset of a neurologic illness between April 2016 and December 2016 were reported to public health officials from 9 reference hospitals in Puerto Rico. All case patients were matched with a group of community controls in a 1:2 ratio based on age group (7-20, 21-39, 40-64, and >65 years) and place of residence (≤1-km radius from a case patient’s residence). The control group, which comprised members of the community who had resided continuously at the enrollment site for the past 2 months, were enrolled within 1 week of each matched case patient.
All study participants completed a questionnaire on demographics, exposures, behaviors, and medical history over the prior 2 months, and serum, urine, and saliva specimens were collected. Acute Zika virus infection was identified in any participant with a positive reverse transcription-polymerase chain reaction result in any of the laboratory specimens obtained or anti-Zika virus immunoglobulin M detected in serum by enzyme-linked immunosorbent assay.
Among a total of 47 potential case patients who were enrolled, a diagnosis of GBS was confirmed in 39 (83%). When case patients and controls were compared, identified GBS risk factors included acute illness within the prior 2 months (82% vs 22%, respectively; matched odds ratio [MOR] 12.8; 95% CI, 4.6-35.3); acute Zika virus infection (23% vs 4%, respectively; MOR 16.0; 95% CI, 2.1-120.6); and any laboratory evidence of Zika infection (69% vs 24%, respectively; MOR 36.0; 95% CI, 4.9-262.5). No additional behaviors, exposures, or medical history variables were considered to be risk factors.
The small sample size used in the study was associated with a wide range in confidence intervals, undetermined generalizability, failure to identify alternative GBS triggers, and inability to evaluate timing of the infection. The pathophysiology of Zika virus infection and risk factors for development of GBS warrant further investigation.
Dirlikov E, Medina NA, Major CG, et al. Acute Zika virus infection as a risk factor for Guillain-Barré syndrome in Puerto Rico. JAMA. 2017;318(15):1498-1500.