Further evidence of a link between Zika virus and Guillain-Barré syndrome

By Nicole MacKee
Researchers have linked a cluster of cases of Guillain-Barré syndrome in Colombia to Zika virus infection, supporting previous suggestions of an association.

The prospective study, published in the New England Journal of Medicine, investigated a spike in the number of cases of Guillain-Barré syndrome that coincided with a Zika virus outbreak in Colombia between October 2015 and March 2016.

In this period, Colombia recorded 2603 laboratory-confirmed cases of Zika virus, as well as more than 58,790 suspected cases. The frequency of Guillain-Barré cases in Colombia at this time jumped from a baseline rate of about 20 cases per month to about 90 cases per month, the researchers reported.

Clinical investigation of 68 patients with Guillain-Barré syndrome at six Colombian hospitals found that 97% had had symptoms compatible with Zika virus – fever (69%), rash (59%), headaches (34%), myalgias (34%), nonpurulent conjunctivitis (25%) and arthralgias (22%) – in the four weeks preceding the onset of the neurological symptoms. The median period between onset of Zika virus symptoms and Guillain-Barré symptoms was seven days.

Nerve conduction studies and electromyography were conducted in 46 patients, and 78% had results consistent with the acute inflammatory demyelinating polyneuropathy subtype of Guillain-Barré syndrome.

Of the total cohort, 42 patients were tested for Zika virus using reverse-transcriptase polymerase chain reaction assays, and 40% of patients had positive results.

An accompanying editorial said the study highlighted the diagnostic challenges of confirming a link, with definitive diagnoses of both Zika virus and Guillain-Barré syndrome in 20% of the total cohort.

Professor Matthew Kiernan, Bushell Chair of Neurology at the University of Sydney, said the temporal profiles of the peak in Guillain-Barré syndrome coinciding with the peak in Zika virus infection strengthened previous reports of an association. However, he said it was difficult to show cause and effect.

‘The positivity of Zika in the blood and serum only tends to last for about a week, and Guillain-Barré usually starts to come in in the postinfectious period, so seven to 10 days,’ Professor Kiernan said.

Professor Kiernan said it was useful for Australian clinicians to be aware of the association, particularly in travellers returning from Zika endemic countries. He said Australian clinicians would be more familiar with Guillain-Barré’s association with Campylobacter jejuni.
N Engl J Med 2016; doi: 10.1056/NEJMoa1605564.
N Engl J Med 2016; doi: 10.1056/NEJMe1611840.

Picture credit: © nopparit/iStockphoto.