Anticipating the Challenges of Zika Virus and the Incidence of Guillain-Barré Syndrome

Guillain-Barré syndrome (GBS) most commonly presents with acute progressive paralysis with absent deep tendon reflexes.1 Bacterial and viral infections can precede the onset of this neurological emergency. In recent years, cases of GBS have been associated with arboviral infections including dengue and chikungunya. As of February 2016, 6 countries affected by outbreaks of Zika virus infection have reported an increased incidence of GBS.2 While some have postulated that concurrent circulation of dengue or other factors could contribute, a case-control study of patients who developed GBS during a Zika outbreak in French Polynesia provides evidence that Zika infection is the culprit.3 In response, the World Health Organization recently released a statement on GBS aimed at health care professionals and policy makers in countries affected by Zika.2 There is concern that the Zika outbreak may soon affect the United States. Aedes aegypti and Aedes albopictus, mosquito vectors of Zika virus, are present in much of the country during the warmer months. Neighboring nations, including Mexico, currently report transmission of Zika. One recent study estimated that 60% of Americans live in regions at risk for the spread of Zika.4 In the French Polynesia outbreak, 66% of the population was infected with Zika and the incidence of GBS was estimated at 0.24 cases per 1000 infections.3 Numerous factors will influence the number of cases of GBS in the United States. However, if conditions were to mimic the French Polynesian outbreak, then as many as 30 000 cases of Zikaassociated GBS might be expected (population 318 million; 60% of the population at risk for infection; 66% infection rate in those at risk; 0.24 cases/1000 Zika infections), representing a roughly 10-fold increase from the baseline incidence of GBS nationally. As neurohospitalists who frequently care for patients with neuromuscular emergencies, we seek to anticipate challenges that could face our health care system if the incidence of GBS were to sharply rise with the arrival of Zika.