Zika virus is associated with a host of medical issues, and in Latin America, health officials are now finding that reported cases of the virus track closely with the onset of a temporary paralysis called Guillain-Barré syndrome.
Researchers say that means an increase in GBS could be a signal that Zika is spreading. Zika infection can present in many ways, from nearly no symptoms to full-blown febrile illness. Most people tend toward no symptoms, making the dramatic presentation of GBS a more clear sign of infection.
“Reports of the Guillain–Barré syndrome could serve as a sentinel for [Zika] and other neurologic disorders linked to [Zika], including microcephaly,” the researchers wrote Wednesday in the New England Journal of Medicine, referring to the birth defect caused by the virus when it infects pregnant women.
This comes after warnings from scientists studying the relationship between Zika and GBS in Tahiti that Latin American countries needed to prepare for the expensive and extensive care that goes along with GBS.
“It is clear that increases in the incidence of the Guillain–Barré syndrome to a level that is 2.0 and 9.8 times as high as baseline, as we have reported here, impose a substantial burden on populations and health services in this region,” wrote the team, made up of researchers from the World Health Organization, the Pan American Health Organization, and individual countries’ health ministries.
The researchers found that nearly 1,500 of the more than 164,000 people with confirmed or suspected Zika infection they surveyed came down with GBS. As the number of Zika infections rose and fell during a one-year period ending in March, so did the numbers of people suffering from the temporary paralysis associated with GBS.
According to the World Health Organization, there is a “scientific consensus” that Zika causes GBS.
The virus is primarily spread by mosquitoes, but can be transmitted through sex. When it infects pregnant women, it can cause debilitating birth defects in their fetuses.
For the new report, officials reporting from six countries — Colombia, the Dominican Republic, El Salvador, Honduras, Suriname, and Venezuela — as well as the state of Bahia in Brazil, found GBS surged during the Zika epidemic, with rates increasing from 100 percent in El Salvador to 877 percent in Venezuela.
The researchers also found that the incidence of GBS was 28 percent higher in men than women, which matches what scientists have seen in cases of GBS induced by other infections.
Studying the link between Zika and GBS has been challenging because other viral illnesses, including the one caused by closely-related dengue virus, also cause GBS. Distinguishing between the two viruses in tests is difficult.