Guillain-Barré syndrome risk among individuals infected with Zika virus: a multi-country assessment

Abstract

Background: Countries with ongoing outbreaks of Zika virus have observed a notable rise in reported cases of Guillain-Barré syndrome (GBS), with mounting evidence of a causal link between Zika virus infection and the neurological syndrome. However, the risk of GBS following a Zika virus infection is not well characterized. In this work, we used data from 11 locations with publicly available data to estimate the risk of GBS following an infection with Zika virus, as well as the location-specific incidence of infection and the number of suspect GBS cases reported per infection.

Methods: We built a mathematical inference framework utilizing data from 11 locations that had reported suspect Zika and GBS cases, two with completed outbreaks prior to 2015 (French Polynesia and Yap) and nine others in the Americas covering partial outbreaks and where transmission was ongoing as of early 2017.

Results: We estimated that 2.0 (95% credible interval 0.5-4.5) reported GBS cases may occur per 10,000 Zika virus infections. The frequency of reported suspect Zika cases varied substantially and was highly uncertain, with a mean of 0.11 (95% credible interval 0.01-0.24) suspect cases reported per infection.

Conclusions: These estimates can help efforts to prepare for the GBS cases that may occur during Zika epidemics and highlight the need to better understand the relationship between infection and the reported incidence of clinical disease.

Keywords: Guillain–Barré syndrome; Zika virus; neurological disorder; vector-borne diseases.

Fig. 1

Suspect GBS and Zika case data at the 11 locations that we consider on a linear scale (a) and a log-log scale (b); note that Yap is missing from panel ‘b’ because no GBS cases were detected there. Using the raw GBS and case data (a) there is a positive though not statistically significant correlation of 0.54 (Pearson correlation, 95% confidence interval −0.08 to 0.86). The model, however, considered the uncertainty and variability in these observations and showed a significant relationship indicated by grey lines for the estimated median number of reported suspect GBS cases for a given number of reported suspect Zika cases in an unspecified location (solid) and the 95% credible interval of that estimate (dashed)

Fig. 2

Mean and 95% CrI for the estimated risk of reported GBS related to ZIKV infection at each location and overall

Fig. 3

Mean and 95% CrI for the estimated suspect Zika cases reported per ZIKV infection during an outbreak at each location and overall