French scientists say they have proved a link between the Zika virus and a nerve syndrome called Guillain-Barré, suggesting countries hit by the Zika epidemic will see a rise in cases of the serious neurological condition.

Guillain-Barré (GBS) is a rare syndrome in which the body’s immune system attacks part of the nervous system. It usually occurs a few days after exposure to a virus, bacteria or parasite.

In a retrospective study analysing data from a Zika outbreak in French Polynesia during 2013 and 2014, researchers led by Arnaud Fontanet of France’s Institut Pasteur calculated the estimated risk of developing Guillain-Barré Syndrome (GBS) at 2.4 for every 10,000 people infected by Zika.

“This work is significant because it allows for the confirmation of the role of Zika virus infection in the occurrences of the severe neurological complications that constitute Guillain-Barré Syndrome,” said Fontanet, Pasteur’s head of the emerging diseases epidemiology.

“The regions which are affected by the Zika virus epidemic are likely to see a significant increase in the number of patients with serious neurological complications and, when possible, should increase the capacity of health-care facilities to receive patients needing intensive care.”

Three to five per cent of GBS patients die from complications, including blood infection, lung clots, cardiac arrest and paralysis of the muscles

The World Health Organisation has declared an outbreak of the mosquito-borne Zika virus spreading from Brazil an international health emergency. This declaration was largely based on evidence linking Zika to a birth defect known as microcephaly, marked by a small head and underdeveloped brain, but the WHO is also concerned about rising reports of cases of GBS in countries hit by Zika.

It is not yet clear whether the Zika virus actually causes microcephaly in babies, but experts say the evidence of a link is growing.

Fontanet’s team analysed data from 42 patients who developed GBS at the time of the French Polynesian epidemic and found that every one had evidence of a previous infection with Zika.

Tests also showed 93 per cent of them had been infected with Zika recently – within three months prior to developing GBS.

Jeremy Farrar, an infectious disease specialist and director of the Wellcome Trust global health charity, said the study, published in The Lancet medical journal, “provides the most compelling evidence to date of a causative link” between Zika and GBS.

“The increase in reported cases of Guillain-Barré in Brazil and other South American countries seems to suggest that a similar situation may be occurring in the current outbreak, although the link is yet to be proven definitively.”

According to WHO, even with the best healthcare services available, some three to five per cent of GBS patients die from complications, including blood infection, lung clots, cardiac arrest and paralysis of the muscles that control breathing.

Zika virus and Guillain-Barré Syndrome explained

A link has been found between Zika virus infection and Guillain-Barré Syndrome (GBS), a rare disorder that affects the nervous system and can result in disability and death.

What is Guillain-Barré syndrome (GBS)?
GBS is a rare but serious disorder in which the immune system is thought to run out of control and attack peripheral nerves. Symptoms develop rapidly, causing muscle weakness and pain. In severe cases muscles affecting speech, swallowing and breathing may be paralysed. In about 20 per cent to 30 per cent of cases, GBS can lead to respiratory failure, and about five per cent of patients die.

What causes GBS?
In most cases, GBS develops after a mild infection of the sort that can cause cold symptoms, sore throats or stomach upsets. Scientists believe it is triggered by the immune system overreacting to bacterial or viral infection.

How common is GBS?
Thankfully, Guillain-Barré syndrome is rare. Across Europe and North America it affects only one to two members of the public out of 100,000 each year. One of the most common risk factors is infection by the food-poisoning bug Campylobacter jejuni, a common cause of gastroenteritis found in contaminated poultry. On very, very few occasions, GBS has been known to occur after receiving a flu jab.

What is the connection between GBS and Zika virus?
A group of 42 patients diagnosed with GBS on the Pacific island of Tahiti, French Polynesia, experienced symptoms of Zika infection some six days before they started to develop neurological problems. All had Zika virus antibodies in their blood. Based on an analysis of data from these patients, experts calculated a GBS incidence rate of 24 cases per 100,000 people infected with the Zika virus. Despite the risk still being relatively low, this is much higher than the incidence rate for the general population.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.