Joana retired from swimming after the last Olympic Games in London, partly because she felt she could no longer compete at the top level and partly because she has a new battle to fight.
As a child Joana was repeatedly sexually abused over many years in a country and, in particular, a region where the issue is rarely talked about and where offenders are rarely prosecuted.
"When a child is raped or abused here, even if there's an investigation, the way it happens is never sympathetic to the victim," says Joana at her apartment in the northern city of Recife.
Joana was abused by someone she knew and trusted but that's not always the case.
|Joana Maranhao has founded the |
campaign group Infancia Livre
"It's worse for poor kids in this region," Joana tells me.
"But it's not about how poor or rich you are. Here it was almost seen as normal and the police have nowhere near enough people to investigate."
Joana's "new race" - as she puts it - is her charity and campaign group, "Infancia Livre" (Free Childhood).
She's determined to help young people, many without the education and drive that she has, who are victims of abuse in a part of Brazil that has a terrible reputation and record for protecting its youth.
Recife, and the wider coastal region in the northern state of Pernambuco, is one of the fastest growing regions in Brazil.
With its long white beaches it's an increasingly popular destination and where four football World Cup games will be played his summer.
|Recife football stadium|
Just a block from the beach, as music blares from the open boot of a car, men stand around drinking and watching a group of women a few yards away.
This is the city's red light district but the difference here is that while they may dress and make themselves up like women some of these girls are only just in their teens. One in four sex workers here is thought to be a child.
Aginaide Lynch is a co-ordinator for the Happy Child charity here in Recife.
She works with street children or those caught up in the sex trade. They have a safe house and other centres in the city dedicated to trying to turn lives around but she admits that with minimal official help and facing such overwhelming challenges, it's just a drop in the ocean.
"In this region, the north-east, people come here specifically for this and it'll get worse during the cup," says Ms Lynch.
She says that for the so-called "sex tourists", it's "easy and formalised".
"Even when men arrive at the airport, taxi drivers or hotel staff help them to find girls. The police are usually absent or even compliant in the business of child abuse so we have to take care of the problem ourselves and get the kids off the streets."
|A government poster campaign calls |
on the public to protect Brazil's children
It's not always girls and boys from the streets, with drugs addictions and absent family structures, that fall victim to the sex tourists.
Pregnant at 16, Ana's own childhood is already lost. She's not a prostitute but has been having sex since she was 12. Ana - not her real name - says girls here go with foreigners because they are wealthy and generous.
Ana is from a working class background and, although her dad no longer lives at home, her mother clearly cares about her daughter's plight. But when, exasperated, her mum went to the police, they didn't even recognise Anna as a victim.
"I've got lots of friend who go with foreigners - gringos. They come here for the girls, you know - working girls, Ana tells me as she sits surrounded by baby clothes, six months into her pregnancy.
She's clearly too young and too vulnerable for the situation she's in but shrugs her shoulders and says: "The guys have lots of money and give the girls loads of things like a place to live or jewellery."
The laws in Brazil regarding child abuse are, on paper at least, relatively strong.
Joana Maranhao's revelations about her past and her willingness to speak out have even led to a new law, in her name, extending the time by which perpetrators of crimes against children can be prosecuted.
But it's not enough and, especially here in the north of the country, there are cultural barriers to break down as well as legal ones.
Brazilian society is often accused of sexualising children. The Novina phenomenon, where internet videos and songs portray young girls as attainable, sexual objects, is strong in this region.
|Jessica Barbosa from Action Aid|
"It's a situation that we think is going to be worse in the World Cup because we have men from outside," she says.
"We have vulnerable girls who need money and who think they'll have a better life in other countries. And we have no serious public policies to prevent this situation."
Twelve-year-old Andrea is proof of that.
She has not been abused but only thanks to her mother's vigilance. She tells me how she's unable to rely on the law to stop older men harassing or trying to lure her daughter with gifts from clothes to popcorn.
So she's had to make her a virtual prisoner in her own home.
A high-profile global campaign, called "It's a Penalty" and fronted by English and Brazilian footballers, warns World Cup visitors not to take advantage of Brazil's reputation for easy sex.
In this World Cup city, kids high on drugs sell themselves for the price of a cup of coffee.
It's an ugly business that embarrasses Brazil when the country is showing itself off to the world.
The Brazilian Health Ministry has dropped an online campaign entitled "I'm happy being a prostitute".
The message was part of a wider education programme about sexually-transmitted diseases and was aimed at reducing prejudice against sex workers.
Health Minister Alexandre Padilha said he had never endorsed the advert: "I do not think this is a message the ministry should be sending."
Critics in Brazil say the campaign glorified prostitution.
Mr Padilha said the message was being tested on the ministry's website, but it was not meant to be published.
"For as long as I remain in office, an ad like that will not be part of our campaigns," he told Agencia Estado. Another slip like that and you may not remain in office very long.
Sports giant Adidas is suspending the sale of World Cup T-shirts after Brazil's authorities complained they sexualised the country's image.
One read "Looking to score?" next to a scantily-dressed woman; another printed a heart shaped like a bikini-clad bottom with the phrase "I love Brazil".
Brazil's tourism board, Embratur, says it is vehemently against any products that link Brazil's image to sex appeal.
Adidas is one of the World Cup's main sponsors and its ball provider.
Following the controversy, the company said it was withdrawing the T-shirts - a limited edition meant for sale in the United States.
"Adidas always pays close attention to the opinion of its consumers and partners," its statement read.
"Therefore, it is announcing that these products will not be sold anymore."
Earlier on Tuesday, the country's tourism ministry had already criticised the products saying "any links between national icons and images with sex appeal" were against the country's official marketing policies.
"Such an attitude indirectly contributes to committing crimes such as sexual child and adolescent exploitation," it said.
Brazilian President Dilma Rousseff also reacted, tweeting that Brazil was happy to greet tourists for the World Cup. But her country was also ready to fight sexual tourism, Mrs Rousseff wrote.
In a statement, Brazil's Embratur said that "Brazil does not tolerate this type of crime on its territory."
Brazil says it has been trying to distance itself from the sexual stereotypes that marked the country for decades.