Neurological complications of Zika virus: Experience in French Polynesia

Abstract

Zika virus (ZIKV) was discovered in 1947 in Africa. From its discovery to 2007, less than 20 human infections have been reported. ZIKV emerged for the first time in the Pacific in the Federated States of Micronesia in 2007, emergence was limited to Yap Islands and severe complications were not described. The second emergence in the Pacific occurred unexpectedly in French Polynesia (FP) in 2013, where ZIKV caused a large outbreak with about 30.000 symptomatic infections. During this outbreak the first complications of ZIKV infections and the potential for non vector-borne transmission of ZIKV (materno-fetal, sexual, and transfusion) were described. From FP, ZIKV spread throughout the Pacific and subsequently emerged in Latin America in 2015. The first case of Guillain-Barré syndrome (GBS) occurring immediately after a ZIKV infection was reported in FP on December 2013. During the following three months additional 41 GBS cases were reported. The increase by 20 fold of the usual incidence of GBS in FP quickly led to an overload of the neurology and the intensive care units (ICU) (16 patients were hospitalized in the ICU and 9 of them required mechanical ventilation). A case-control study conducted in FP demonstrated the link between ZIKV and GBS. The estimated incidence of GBS during the FP outbreak was 0.24 per 1.000 ZIKV infections. Neurological complications are common features of flaviviruses infections, but GBS complicating ZIKV infection had never been reported before the FP outbreak. Other neurological diseases such as myelitis, encephalitis and meningoencephalitis were also reported during the FP outbreak. The increase in GBS and other neurological diseases incidence and also congenital abnormalities (including microcephaly) related to ZIKV infection was further described at the time ZIKV emerged in the Americas. FP was the first country to face a large ZIKV outbreak and clinical complications of ZIKV infection were unexpected. One of the lessons learned from this outbreak is that once a new pathogen starts causing large outbreaks, even in small countries, the scientific community should be prepared to the worst case scenario.