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Scientists find first links between Zika and temporary paralysis: What you need to know

Army soldiers in Rio de Janeiro set up a sign that reads in Portuguese "A mosquito is not stronger than an entire country" as troops across Brazil try to tackle the Zika virus. (AP Photo/Silvia Izquierdo)
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A retrospective study of a Zika outbreak in Tahiti in 2013-14 has found evidence of a link between the virus and a temporary form of paralysis. The finding is the latest sign that the virus that has existed for over 50 years may be more threatening than once believed.

As concerns over the virus have mounted in recent months, officials in Tahiti went back and analyzed blood samples from 42 adults who were diagnosed with Guillain-Barré syndrome, a rare neurological disorder, around the time the virus was raging on the French Polynesian island. All but one showed signs of Zika antibodies, indicating they had been previously infected.

Writing in the journal Lancet, scientists warned that at-risk countries in the Americas where the virus is spreading "need to prepare for adequate intensive care beds capacity to manage patients with Guillain-Barré syndrome."

Guillain-Barré occurs when the immune system goes awry and attacks the nerves. This typically happens two to eight weeks after an infection and typically begins with a tingling sensation and can progress to paralysis. One study found that a quarter of the patients need respiratory assistance and that the death rate is as high as one in 20.

In the cases documented in Tahiti, the symptoms progressed very fast. The patients reported symptoms consistent with the Zika virus a median of six days before they showed neurological symptoms. Most appeared to have a variant of the syndrome known as acute motor axonal neuropathy, or AMAN, which is characterized by paralysis and loss of reflexes. The median age of the patients was 42 years, and there were 31 men and 11 women. Nearly all were born in French Polynesia.

The researchers speculated that past infection with the dengue virus might have made them more vulnerable to the syndrome but did not find any evidence of this.

The study, however, contained some positive news. The patients' outcomes were "generally favorable," the researchers wrote. And they had a "faster recovery than usually observed in typical Guillain-Barré syndrome," according to the researchers.

Those outcomes are in sharp contrast to what health officials are reporting on the ground in Latin America.

Zika has been linked to birth defects. Now it may be causing paralysis.

Turbo, Colombia, has reported a recent outbreak of Guillain-Barré that included five cases, all of them severe. According to Washington Post correspondent Nick Miroff, who visited the city, "Three patients have died. One is fighting for his life in an intensive care unit. The fifth, a 10-year-old girl, hasn’t been able to move her legs in a week."

In total, Colombia has reported 97 case of Guillain-Barré.

In the United States, the Centers for Disease Control and Prevention has confirmed three cases, including one in Puerto Rico, of Guillain-Barré related to Zika. Over the weekend, Honduras reported that a 29-year-old pregnant woman showing symptoms of Zika has been diagnosed with Guillain-Barré, according to the Associated Press.

Read more:

Why the United States is so vulnerable to the alarming spread of Zika virus

Beyond Zika: The map of things that keep NIH’s infectious diseases director up at night

NIH officials accelerate timeline for human trials of Zika vaccine, saying they will now begin in the summer

Why Zika is a ticking 'time bomb' for Latin America