A CDC official says 1,500 pregnant women in Puerto Rico might be infected and not know it.
It's called antibody-dependent enhancement (ADE), wherein the dengue vaccine sets up severe disease in those not previously exposed — and it might have repercussions for Zika.
In other developments, the Zika surge continues in Puerto Rico, more US travelers have been infected, and the virus has spread to more Caribbean locations.
The study sheds light on how Zika antibodies bind to the virus. Also, Florida is investigating four possible local cases now, all from the same two counties: Broward and neighboring Miami-Dade.
Also, as Florida officials continue their investigation into two possible locally acquired cases, they add 11 more travel-linked infections, including in pregnant women.
The updates include an expanded definition of Zika congenital syndrome from PAHO and revised CDC guidance on testing pregnant women and on preventing sexual spread.
New York City confirms its first Zika-related microcephaly case, Florida is investigating a possible 2nd local infection, and Puerto Rico turns down a CDC plan to spray for mosquitoes.
Also, researchers report that Culex quinquefasciatus mosquitoes are a potential Zika vector, and CDC notes 3 new cases of birth defects.
As officials probe the source of the infection, mosquito control activities are under way in the area and Zika kits are being distributed.
Researchers found the virus in Aedes mosquitoes near the homes of patients in southern Mexico, and another team found that two species commonly found in the US aren't likely to spread the disease.
