(CNN) -- Brazilian model Mariana Bridi da Costa, whose hands and feet were amputated in a bid to save her from a deadly and little-known illness, died early Saturday, two friends of the model told CNN.

Brazilian model Mariana Bridi da Costa died Saturday after undergoing multiple amputations.

"Unfortunately Mari couldn't resist any longer. She passed away at 3 a.m. today," Henrique Fontes, executive director of Miss World Brazil, said in an e-mail to CNN.

Renato Lindgren, a friend of the model who runs a blog dedicated to her, confirmed da Costa's death.

On his blog, Lindgren wrote that he and other friends were going to the hospital.

"On behalf of all the family, we are grateful for the support and the affection that the entire world has sent to us," he wrote.

Da Costa, 20, had fought a pernicious disease that has ravaged her body and forced doctors to perform the amputations and extract part of her stomach as well as both kidneys.

She had been breathing through a respirator, officials at Dorio Silva Hospital in the Brazilian state of Espirito Santo said Friday.

Da Costa suffered from necrosis, or the fast deadening of tissue, caused by septicemia. Septicemia, triggered by a bacterial infection, causes insufficient blood flow that can lead to organ failure.

Da Costa first sought medical advice after feeling ill in late December. Hospital officials said she was transferred to Dorio Silva on January 3 in "septic shock," a serious medical condition caused by an inflammation.

Da Costa was first diagnosed as suffering a urinary tract infection. By the time the infection was detected, it had developed into septicemia.

Doctors decided to amputate first her hands and then her feet after the condition reduced the amount of oxygen being delivered to her limbs.

Just less than one month ago, da Costa was a healthy young woman well on the way to achieving her dream of becoming a world class model.

She placed sixth in the Miss Bikini International competition in China last year and took first place for the "Best in Swimsuit" category. In 2007 and 2008, she came fourth in the contest to become Brazil's entrant for the Miss World pageant.

Thiago Simoes, da Costa's fiance, said she was on her way to international stardom, signing with prominent model scout Dilson Stein, who brought Brazilian models, including Gisele Bundchen and Luize Altenhofen, to the world stage.

"All the agencies were very interested in knowing her. I know for a fact that they would have loved her because Mariana is beautiful," Stein told Brazil's Tribuna newspaper.

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Simoes told CNN that da Costa woke up from a coma 10 days ago and told him how much she wanted to be alive.

"She told me she was praying to stay alive, that she still had a lot to do on this earth, that she wanted to go on with her plans," he said.

"She comes from a humble family and she was the main breadwinner," said Simoes, who refuted rumors that da Costa was dieting and that might have affected her health.

"She never dieted, never took pills...she is a very simple, very warm human being," he said.

A doctor who recently published an article in The New England Journal of Medicine on the disease, told CNN that little was known about the illness, although it is the tenth leading cause of deaths in the United States.

"We know a lot about what happens once a patient contracts the illness but we know very little about what causes it," said Dr. Greg Martin of Emory University in Atlanta.

Martin said sepsis is a "response" to an infection that can cause the immune system to lose its balance.

"Basically, the immune system goes haywire after contracting an infection and begins to overreact," he said.

Men are more susceptible than women, Martin said.

News of da Costa's condition spread quickly throughout Brazil and then worldwide. A message on her Web site said that the volume of traffic had caused it to crash, and that the site had received more than 15,000 hits in two days.

"The whole world, I repeat, the whole world is touched by the case of Mariana," it said.

The message said they had received "e-mails of solidarity from all corners of the world: Australia, Ukraine, Czech Republic, France, Italy, USA, Russia, etc."

CNN's Hilary Whiteman and Helena de Moura contributed to this report.

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