The Miami Dolphins and Miami Marlins say they've intensified mosquito-control treatments at their stadia because of the Zika virus.
The Dolphins' stadium is more than 16km from the nearest area of the virus outbreak.
Even so, the Dolphins say they decided weeks ago to undertake additional treatments as a precaution.
Construction workers are at the site daily completing the latest phase in a $500 million renovation. The first home pre-season game is next Thursday against Tennessee.
The Marlins and Miami-Dade County have stepped up spraying in and around Marlins Park "in an abundance of caution" team president David Samson said on Thursday.
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Treatments targeting the mosquito that transmits Zika are being used even though the Marlins play most of their home games indoors under a retractable roof.
Marlins Park is about 3km from the nearest area of virus outbreak.
