By Stephanie Nebehay & Julie Steenhuysen
GENEVA/CHICAGO (Reuters) – Researchers around the world are now convinced the Zika virus can cause the birth defect microcephaly as well as Guillain-Barre syndrome, a rare neurological disorder that can result in paralysis, the World Health Organization said on Thursday.
The statement represented the U.N. health agency's strongest language to date on the connection between the mosquito-borne virus & the two maladies.
p> The WHO moreover reported the first sign of a possible rise in microcephaly cases outside Brazil, the hardest-hit country so far in an outbreak spreading rapidly in Latin America & the Caribbean. Neighboring Colombia is investigating 32 cases of babies born with microcephaly since January, & eight of them so far have tested positive for the Zika virus, the WHO said.
"Based on observational, cohort & case-control studies, there is a strong scientific consensus that Zika virus is a cause of GBS (Guillain-Barre syndrome), microcephaly & other neurological disorders," the WHO said on Thursday.
In its previous weekly report, the WHO had said Zika was "highly likely" to be a cause.
The WHO in February declared the Zika outbreak an international health emergency, citing a "strongly suspected" relationship between Zika infection in pregnancy & microcephaly.
Although Zika has not been proven conclusively to cause microcephaly in babies, evidence of a link was based on a major spike in Brazil in cases of microcephaly, defined by unusually small head size that can result in developmental problems.
Brazil's health department this week reported 944 confirmed cases of microcephaly, & most are believed to be related to Zika infections in the mother.
In recent scientific studies, researchers have seen evidence of the virus in brain cells of stillborn & aborted fetuses. They moreover have seen signs that the brain had been growing normally, yet that growth was disrupted & the brain actually shrank.
Scientists have been closely monitoring for possible microcephaly cases outside Brazil to rule out that environmental factors in Brazil may have been involved. Colombia has been following the pregnancies of women infected with Zika after seeing widespread transmission of the virus since October.
The latest WHO report now reflects an increase in microcephaly & other fetal abnormalities in Colombia, where 56,477 suspected cases of Zika infection have been reported, including 2,361 laboratory-confirmed cases.
Six countries where Zika is not known to be spreading by mosquitoes have now reported locally acquired infections, probably through sexual transmission, the WHO said, naming Argentina, Chile, France, Italy, New Zealand & the United States.
To date, 13 countries or territories have reported increased incidence of Guillain-Barre or laboratory confirmation of a Zika virus infection in people with the rare autoimmune disease, it added.
(Reporting by Stephanie Nebehay & Julie Steenhuysen; Editing by Richard Balmforth, Michele Gershberg & Will Dunham)
HealthInfectious DiseasesZika virusmicrocephalyBrazil