Dancers - some in elaborate costumes - strutted into the final round of the Rio Carnival's samba championship on Monday, capping a wild party that has helped Brazilians forget about Zika and other worries.

The six last samba schools were preening their spectacular feather headdresses and adjusting the shining garments favoured by lead dancers ahead of the all-night parades.

Another six rival ensembles had their turn through the night on Sunday at the climax of a Carnival season estimated to attract 5mn people. A champion samba school will be announced on Wednesday, closing an event that calls itself "the greatest show on Earth."

Some 70,000 fans cheered, sang and shook their hips overnight Sunday to Monday in the stands of Rio's purpose-built dancing stadium, the Sambadrome, as competing samba schools passed in a blur of feathers, glitter and flesh.

Extraordinary floats rolled down the runway, including a giant rat representing the 10.7% inflation hurting ordinary Brazilians in a sickly economy. Another float in the shape of a golden football had Barcelona FC and Brazil striker Neymar's father standing on top.

The outpouring of colour, pounding drums, joyful song, and samba dancing helped the crowds put aside fears over the Zika virus, the economy and attempts to impeach President Dilma Rousseff.

"Despite the problems in our country, our people can't lose their love of partying. And whatever happens in our country, it's still the country of samba," said Luanny Victoria, 19, before heading off to dance in a skimpy golden outfit with vast green feather wings.

"People have to put those problems aside, at least for the three days of Carnival."

No Zika fear  

Fear of catching the Zika virus from mosquitoes has become a national obsession in Brazil after a rash of babies born to infected mothers were found to have severe brain and skull defects.

Scientists have raised the alarm level with suggestions that saliva and blood could possibly transmit the virus. US health authorities say they have confirmed a case of Zika transmission in Texas through sexual contact.

But at the Rio Carnival, partygoers were determined not to let Zika spoil the fun.

Many said they were using insect repellent - a seemingly sensible step with so much skin exposed at the open air event. However, there were limits to how much they were prepared to stress.

"I use repellant, but the truth is that Brazilians couldn't give a hoot about Zika. It's Carnival," said Marilene Borba, 67, who was watching the parades.

Serious about fun  

Rio will become South America's first city to host the Summer Olympics this August and the Carnival looked forward to the event at its opening ceremony with a huge model of the Olympic torch.

One samba school featured Greek gods, gyrating judo fighters, men on bicycles suspended in the air, and in a nod to the Paralympics, a dancing and singing wheelchair contingent.

Certainly if organising parties was an Olympic sport, Brazil's Carnival would sweep the podium.

Samba schools spend as much as $3mn on productions that take nearly the whole previous year to prepare, then just over an hour to perform. And although nearly the entire cast of several thousand is unpaid, the choreography would make Broadway jealous.

This year, hard economic times have hurt the Carnival industry, denting sponsorship and raising the prices of imported fabrics used to make costumes. In 48 Brazilian cities, the Carnival was cancelled altogether.

But Lucas Fernandes, a 17-year-old drummer, said he lived for this chance to parade in the Sambadrome.

"The Rio de Janeiro Carnival is something magical," said Fernandes, who practised twice a week for 10 months to be ready.

"Although Brazil is a country with problems, the Carnival brings us happiness."