Zika infection may be worse in people already exposed to a common virus

A previous encounter with a disease that is rampant across Latin America could leave people more vulnerable to the Zika virus. Antibodies to dengue virus, a relative of Zika, can interfere with the immune system’s response to Zika and boost the virus’s ability to replicate, according to work in two independent labs. That may help explain why the complications of Zika virus infections have been more severe in South and Central America than in previous epidemics elsewhere.

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