Author response: Acute Zika infection with concurrent onset of Guillain-BarrÉ syndrome.

Case report. A 47-year-old Tongan male returning to New Zealand after a 2-week holiday in Tonga presented with 3 days of progressive limb weakness, numbness, unsteady gait, and dyspnea. Two days before departing Tonga (6 days before neurologic symptoms), he developed leg swelling with erythematous and pustular lesions, which were treated with flucloxacillin. He had no medical history, was not taking regular medication, and had a 20 pack-year smoking history. Examination findings included the following: afebrile, pulse 80 beats/min, blood pressure 150/90 mm Hg, respiration 20 breaths/min, and oxygen saturation 98% (air). Cardiovascular and abdominal examinations were unremarkable. Cranial nerves and eye movements were normal. Limbs were hypotonic with globally reduced power (4/5), areflexia, and absent plantar responses. Temperature and pain sensation were impaired in hands and feet. Proprioception and vibratory sensation were impaired in the feet. Romberg test was positive. Full blood count, renal function, electrolytes, creatinine kinase, hemoglobin A1c, C-reactive protein, thyroid function, B12, and folate were normal. Liver enzymes were mildly elevated (ALP 122, GGT 251, and ALT 41 IU/L). Antinuclear antibody was 1:160. CSF showed albuminocytologic dissociation: protein 0.69 g/L (reference 0.15–0.45), white blood cells 2/mL, red blood cells 1/mL, and glucose 3.4 mmol/L (serum glucose 6.0). Spine MRI and chest x-ray were unremarkable. Normal cranial MRI excluded concurrent acute disseminated encephalomyelitis. Nerve conduction study on day 2 of admission revealed demyelinating, predominantly motor, polyneuropathy (table). Serum reverse transcription (RT)-PCR on day 3 after illness onset was negative for chikungunya and dengue RNA and positive for Zika RNA (subsequently negative on day 13). Dengue NS1 antigen (Platelia Dengue NS1; Bio-Rad, Hercules, CA) was negative. Immunoglobulin (Ig)M antibodies (low level) and IgG antibodies (high level) against Zika (EUROIMMUN, Luebeck, Germany) and dengue (PanBio, Brisbane, Australia) were detected on day 3. CSF RT-PCR on day 5 was negative for all 3 viruses. A diagnosis of Guillain-Barré syndrome (GBS) was made. Worsening respiratory function required ventilation support. Five days of Ig was given (0.4 g/kg/d). Serial quantitative neurologic examination showed a steady decline. He was then given 6 plasma exchanges beginning 5 days after the last dose of Ig, i.e., from day 10 of treatment. Respiratory status improved to not requiring mechanical ventilation by day 21. At day 33, when transferred to rehabilitation, he had persistent limb weakness with best power grade 3/5 and remained bedbound.