A study published Feb. 29 online in The Lancet adds to indications the Zika virus is linked to Guillain-Barré syndrome, which can cause temporary paralysis. However, according to a report written by Catherine Saint Louis in the New York Times, experts caution more evidence is needed to be conclusive.
The study focused on 42 patients who contracted Guillain-Barré syndrome during a Zika outbreak in French Polynesia in 2013 and 2014. Determining whether they had the Zika virus was difficult, because the virus stays in the bloodstream only for about a week. None of the patients had active Zika in their blood.
Researchers worked around the problem by adding serum from each patient to live Zika virus in a culture. All 42 patients had antibodies that killed the Zika virus.
The test also was performed on a control group of 98 people matched for age, sex and residence. Only half of the control group had antibodies to kill Zika.
Further, patients were tested for IgM, another antibody indicative of Zika infection. Thirty-one of the 42 Guillan-Barré patients tested positive for the antibody, but only 1o were positive in the control group.
“This is a compelling paper that provides a good deal of objective data to suggest an epidemiological link between recent Zika infection and increased risk of Guillain-Barré syndrome,” Kenneth C. Gorson, MD, professor of neurology at Tufts School of Medicine, said in the New York Times report. “That’s huge, because it’s the first case-control study to establish a potential relationship between Zika virus infection and Guillain-Barré.”
However, the antibody test alone isn’t positive proof that Guillain-Barré is caused by the Zika virus. David W. Smith, PhD, a professor of pathology and laboratory medicine at the University of Western Australia, told the Times that in order to prove a Zika infection, the test also must show that the concentration of Zika antibodies was four times higher than for dengue fever, which is common in Tahiti. Only one of the 42 cases met that standard.
Arnaud Fontanet, MD, head of the epidemiology of emerging diseases unit at the Institut Pasteur in Paris and one of three senior authors of the study, said one reason could be that researchers had used blood samples taken in a three-month checkup, so the concentration of antibodies would have gone down.
“More studies are needed to demonstrate if Zika virus can really cause Guillain-Barré syndrome,” Bart C. Jacobs, MD, PhD, a professor of immunology and neurology at Erasmus MC in the Netherlands, said in the Times report. Nevertheless, Jacobs said the study provided “convincing evidence for a link.”
Photo courtesy of the U.S. Centers for Disease Control and Prevention
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