In an announcement, the RFEF stated Spain captain Busquets, 32, examined optimistic earlier on Sunday, with the remainder of the squad all testing unfavorable.
The RFEF added that those that have been in shut contact with Barcelona midfielder Busquets “will stay remoted” as a preventative measure.
The squad will perform particular person coaching programmes within the build-up to the Euro, which begins on Friday.
Spain’s first match is towards Sweden on June 14 and coach Luis Enrique has till Saturday to make modifications to his squad forward of their opening fixture in Seville.
“Acceptable sporting measures will probably be assessed in response to the scenario of the nationwide workforce captain,” the RFEF stated.
Busquets has performed over 120 occasions for Spain and helped his nation to triumphs on the 2010 World Cup and Euro 2012.
He has additionally gained eight Spanish league titles and three Champions Leagues with Barcelona, in addition to a bunch of different trophies.