We have our strongest evidence yet that Zika virus may be linked to a paralyzing disorder called Guillain-Barre Syndrome - here's what that means

A new report provides the most conclusive evidence to date linking Zika virus to some cases of Guillain-Barré Syndrome, a neurological disorder that causes paralysis that is usually temporary, but in rare cases may be fatal.

As STAT reports, the vast majority of GBS patients who developed the disorder during a Zika outbreak in French Polynesia two years ago had previously been infected with the virus.

What's more, people infected with Zika had a 24 times greater risk of developing GBS, scientists reported in The Lancet medical journal.

Zika is a mosquito-borne virus that causes flu-like symptoms such as fever, joint pain, rash, or red eyes. Zika infections are mild in most individuals except for pregnant women, where scientists have cited a potential link to birth defects such as microcephaly.

In early February, Colombian officials said that three people had died after contracting the Zika virus and developing GBS, and six other deaths were being investigated.

But scientists didn't have direct evidence linking Zika to GBS until now.

What is GBS?

Guillain-Barré Syndrome is a disorder caused by the body's immune system attacking the nervous system outside of the brain and spinal cord. GBS usually begins with weakness and tingling in the legs, which can spread to the arms and upper body.

Most people who develop GBS generally recover well. But in some cases, it can cause almost complete paralysis that can interfere with breathing, blood pressure, or heart rate - which can be fatal.

GBS can occur in people at any age, and affects both genders equally. But the disorder is rare, affecting only about one person in 100,000, according to the National Institutes of Health.

The syndrome usually develops several days or weeks after someone experiences a respiratory or gastrointestinal viral infection, but in rare cases, it may be triggered by surgery. There was a small increase in GBS in people who got the swine flu vaccine in 1976, but the CDC says any risk from flu vaccination is likely very small - smaller than the risk from getting the flu itself.

Causes and treatments

Experts still don't know what causes GBS. The immune system, which normally fights off infections, starts attacking itself, destroying the fatty layers that surround cells in the peripheral nervous system - the part of the nervous system that excludes the brain and spinal cord.

When these fatty sheathes are damaged, the nerves cannot send signals efficiently. This means the brain cannot control the muscles very well, nor can it receive as many sensory signals like textures, heat, or pain. The nerves that connect to the hands and feet are longest, so these parts of the body are affected first.

There is no cure for Guillain-Barré, but there are treatments that can speed a patient's recovery.

Plasma exchange is a technique where blood is removed from the body, the red and white bloods cells are separated from the fluid or plasma that surrounds them, and the blood cells are returned to the body. In immunoglobulin therapy, doctors inject high doses of proteins into the patient that naturally help the immune system attack foreign invaders.

The main thing is to keep the patient's body working properly during the recovery, which may include the use of a ventilator, heart monitor, or other equipment.

Zika virus is primarily transmitted by mosquito bites, but sexual transmission has been reported. It persists for up to a week in the blood, according to the Centers for Disease Control and Prevention. It's unclear how long it can survive in saliva or semen, though there have been reports of the virus in saliva samples.