First Evidence to Show That Zika Causes Guillain-Barre Syndrome

Researchers suspected that the Zika virus causes Guillain-Barré syndrome (GBS), a rare neurological syndrome, but now there’s actual proof of the relationship.

The association between Zika and microcephaly has received a lot of media attention recently, but there is another serious condition in connection with the mosquito-borne illness. According to a report from the World Health Organization (WHO), five of the more than 30 countries with ongoing local Zika transmission — Brazil, Colombia, El Salvador, Suriname, and Venezuela –experienced a 19% increase in GBS cases in 2015, compared with 2014. Up until recently, the connection has been circumstantial.

However, a collaborative team of researchers has uncovered the first evidence that shows a link between Zika and GBS and their results are published in a recent issue of The Lancet.

GBS is a rare neurological disorder that causes the immune system to attack the nerves. Patients commonly experience fatigue, fast heart rate, and shortness of breath. However, the primary concern is weakness and tingling in the lower body that then spreads throughout. In serious cases, muscle weakness can turn into paralysis. In the report, the team states that about 20% to 30% of patients with GBS experience respiratory failure and 5% die from the condition.

During the 2013 — 2014 Zika outbreak in French Polynesia, there was an increase in cases of GBS. Around 32,000 people sought medical attention for possible Zika infection. Blood samples taken between November 2013 and February 2014 identified 42 patients with GBS.

Two control groups were gathered — the first consisted of 98 people who went to the hospital with an illness without fever who were matched for age, gender, and island of residency and the second included 70 people who tested positive for Zika, but did not develop symptoms of GBS.

According to the report, 88% of the patients with GBS had Zika symptoms about six days before neurological symptoms occurred. None of the 42 patients tested positive for Zika by the time they were admitted to the hospital, however, 41 of them (98%) had Zika antibodies and all of them had neutralizing antibodies against the virus. In the first group of controls, 54 of the 98 patients (56%) had Zika neutralizing antibodies.

The patients with GBS were hospitalized for an average of 11 days; but for 16 individuals (38%) who were admitted to the intensive care unit, their average stay was 51 days. Twelve of the patients required breathing assistance. Three months after leaving the hospital, 24 patients (57%) were able to walk without help. No deaths were reported.

Because the dengue virus, another mosquito-borne illness, is also common in the French Polynesia, the researchers wanted to see if it was also a risk factor for GBS. About 95% of patients with GBS had signs of previous dengue infection (88.8% and 82.9% of patients in control groups 1 and 2, respectively, did as well). Since the history of dengue infection did not differ much between Zika and non-Zika patients, the researchers determined that the virus does not impact the risk of developing GBS due to Zika.

Based on the findings of The Lancet study, more GBS cases can be anticipated in the upcoming months. This data should be taken with some caution, however, since it is unknown whether the 2013 — 2014 Zika strain is the same as the current outbreak.

The team estimates that 24 out of 100,000 people infected with the Zika virus will develop GBS.

“This is the first study to look at a large number of patients who developed Guillain-Barré syndrome following Zika virus infection and provide evidence that Zika virus can cause GBS,” lead author Arnaud Fontanet, MD, from the Institut Pasteur in Paris, France, said in a news release.

“The results of our study support that Zika virus should be added of the list of infectious pathogens susceptible to cause Guillain-Barré syndrome,” Fontanet affirmed.