Zika Virus and Other Emerging Arboviral Central Nervous System Infections

In recent years, we have observed the emergence and reemergence of a number of arthropod-borne viruses (arboviruses). Zika virus is the most recent addition to this group, first causing sporadic cases of uncomplicated febrile illness followed by sizeable outbreaks in the Pacific. However, the epidemiology and clinical features of Zika virus infection have changed rapidly and dramatically; it is now recognized as causing Guillain-Barré syndrome (GBS) in children and adults and congenital abnormalities in infected fetuses. This article reviews the epidemiology, clinical features, and diagnosis of Zika virus-associated neurologic illness and briefly reviews features of West Nile virus and Japanese encephalitis virus.

Zika virus has emerged as a significant human pathogen in recent years. In 2015, it began to cause large outbreaks of febrile rash illness in South America and the Caribbean. During these large Zika virus outbreaks, a significant increase in the incidence of GBS was also observed in multiple countries/territories. Zika virus-associated GBS has several unique features, including a relatively short interval between febrile illness and GBS onset, an unusually high incidence among older people, and prominent cranial nerve abnormalities. Congenital Zika syndrome includes a myriad of abnormalities, including microcephaly, lissencephaly, hydrocephalus, arthrogryposis, and parenchymal calcifications. Currently, no treatment has been identified for Zika virus, although work on vaccines is under way.

Arboviruses continue to surprise us with unexpected emergence in various locations, the nature of clinical illness, and outcomes. Zika virus presents a classic example of this type of emergence. Ongoing surveillance will be needed to evaluate the long-term pattern of Zika virus and related arboviruses.