Rio's Carnival -- a five day festival of dancing, bared flesh and wild costumes -- go underway in the face of warnings that the Zika virus might make even kissing dangerous.

Mayor Eduardo Paes handed a big golden key to the city to the Carnival's ceremonial King Momo, who promised a spectacular show.

"With great happiness, brotherly love and peace, I declare the best Carnival on Earth open -- our Carnival in the Marvelous City," the dancing king, who is elected ahead of the festivities, said on Friday.


The annual mega-bash famed for lavish -- and skimpily dressed -- samba parades and all-night street dancing is expected to attract as many as five million people.

In Sao Paulo, Brazil's most populous city and its economic capital, Carnival celebrations were kicked off under intermittent summer rain, with a tribute to Carlinhos de Jesus, one of Brazil's most famous salon dancers.

This year's Carnival across Brazil starts under the cloud of the mosquito-transmitted Zika virus, which normally provokes few ill effects, but is blamed for an outbreak of serious birth defects in babies born to mothers infected while pregnant.