More than 5,000 pregnant Colombian women are infected with the mosquito-borne Zika virus, the country's national health institute said on Saturday, as the disease continues its rapid spread across the Americas.

There are 31,555 cases of the disease in Colombia, the national health institute said in a epidemiology bulletin, among them 5,013 pregnant women. The disease has been linked to microcephaly, a condition marked by babies being born with an abnormally small head size that can result in developmental problems.

Much remains unknown about Zika, including whether the virus actually causes microcephaly. Brazil is investigating the potential link between Zika infections and more than 4,300 suspected cases of microcephaly.

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