BACKGROUND: Guillain-Barré syndrome (GBS) is an uncommon autoimmune disorder characterized by progressive bilateral weakness following vaccination or an infection, including Zika virus (ZIKV) infection. After reporting local ZIKV transmission in late 2015, the Puerto Rico Department of Health (PRDH) implemented the GBS Passive Surveillance System to prospectively identify suspected GBS cases, test for ZIKV infection, and assess long-term patient disability.
METHODS: Healthcare providers submitted case report forms and samples (i.e., serum, urine, cerebrospinal fluid [CSF], and/or saliva) to PRDH. All specimens were tested by reverse transcription-polymerase chain reaction (RT-PCR); serum and CSF specimens were also tested by immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA). Confirmed ZIKV infections were positive by RT-PCR; presumptive ZIKV infections were positive by IgM ELISA for ZIKV and negative for dengue virus (DENV); and presumptive flavivirus infections were positive by IgM ELISA for ZIKV and DENV. GBS diagnosis was confirmed by chart review using the Brighton Collaboration criteria. The Modified Rankin Score (MRS) was used to assess long-term disability six-months after onset of neurologic signs.
RESULTS: Through December 16, 2016, 103 suspected GBS cases were reported, of which, 22 (21%) were confirmed ZIKV infections, 28 (27%) were presumptive ZIKV infections, and 16 (16%) were presumptive flavivirus infections. Of 66 cases with evidence of ZIKV or flavivirus infection, median age was 54 (range = 21–88); 34 (52%) were female. The 66 patients were residents of 7 of the 8 public health regions. Similar to trends in incidence of reported ZIKV disease, GBS cases with evidence of ZIKV or flavivirus infection increased starting in May and peaked in August. Among 47 GBS cases with evidence of ZIKV or flavivirus infection and medical chart review, 47 (100%) were treated with intravenous immunogloblin, 32 (68%) received intensive care services, and 15 (32%) required mechanical ventilation. There were two in-hospital deaths. For patients with evidence of ZIKV or flavivirus infection surveyed six-months after onset of neurologic signs (n = 18), median MRS was 2 (range = 0–5), indicating continued slight disability.
CONCLUSIONS: Given ongoing ZIKV transmission in Puerto Rico, PRDH will continue surveillance activities to identify incident cases of ZIKV-associated GBS and assess long-term disability. Prompt reporting and collection of specimens provides laboratory evidence to define the association between GBS and ZIKV infection. In areas with local ZIKV transmission, healthcare providers should increase clinical suspicion of GBS to improve patient prognosis through prompt diagnosis and treatment.