South Africa's president asked the world to pray for his predecessor, Nelson Mandela, and to keep him in their thoughts. NBC's Rohit Kachroo reports. 
 
 Former South African President Nelson Mandela is "responding positively" to treatment for a recurring lung infection after he was taken to a hospital late Wednesday, the presidency said on Thursday. 
 
 "The doctors advise that former President Nelson Mandela is responding positively to the treatment he is undergoing for a recurring lung infection," the presidency said in a statement. "He remains under treatment and observation in hospital." 
 
 In a statement, the current South African President Jacob Zuma said, “We appeal to the people of South Africa and the world to pray for our beloved Madiba [a nickname for Mandela] and his family and to keep them in their thoughts.” 
 
 “We have full confidence in the medical team and know that they will do everything possible to ensure recovery,” he added. “The Presidency appeals once again for understanding and privacy in order to allow space to the doctors to do their work.” 
 
 Mandela, 94, was taken to a hospital just before midnight local time (6 p.m. ET). 
 
 The statement said that Mandela had the “best possible expert in medical treatment and comfort.” 
 
 Mandela has a history of lung problems dating back to when he contracted tuberculosis as a political prisoner in the notorious Robben Island jail under the apartheid regime. 
 
 Slideshow: Nelson Mandela: A revolutionary's life / View images of civil rights leader Nelson Mandela, who went from anti-apartheid activist to prisoner to South Africa's first black president. Launch slideshow 
 
 'Be strong' 
 
 Jackson Mthembu, a spokesman for the African National Congress, said in a statement that the party once led by Mandela “calls on all South Africans and the world to keep Nelson Mandela in their prayers.” 
 
 “We are confident that the treatment will be successful as he is in professional and competent hands,” he said. 
 
 “During these trying times we wish President Mandela well and for his family to be strong," he added. 
 
 Mandela spent nearly three weeks in a hospital in December for treatment of a lung infection and gallstone surgery. 
 
 This was the longest time he had been hospitalized since being released from captivity as a political prisoner in 1990. 
 
 He was also hospitalized earlier this month for what was described as a "scheduled medical checkup." 
 
 Mandela was president of South Africa from 1994 to 1999, the first president of the country to be elected following the fall of the apartheid system. 
 
 President Barack Obama sent his best wishes to the former leader on Thursday. 
 
 "He is as strong physically as he's been in character and in leadership over so many decades, and hopefully he will ... come out of this latest challenge," Obama told reporters at the White House. 
 
 "When you think of a single individual that embodies the kind of leadership qualities that I think we all aspire to, the first name that comes up is Nelson Mandela. And so we wish him all the very best," Obama said. 
 
 NBC News' Matthew DeLuca and Rohit Kachroo, and Reuters contributed to this report. 
 
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 Secrecy over Mandela's health fuels concern for South Africa icon 
 
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 This story was originally published on ||||| Story highlights Mandela remains "under treatment and observation," President Jacob Zuma says 
 
 The anti-apartheid icon also was hospitalized earlier this month 
 
 At the time, officials said it was only for a routine checkup 
 
 Mandela, 94, has been treated for a lung infection before 
 
 Former South African President Nelson Mandela is "responding positively" to treatment after he was readmitted to a hospital overnight for a recurring lung infection. 
 
 President Jacob Zuma's office passed along the doctors' assessment of Mandela, the 94-year-old anti-apartheid icon and nation's first black president. 
 
 "He remains under treatment and observation in hospital," Zuma said Thursday. 
 
 Mandela was conscious when he was taken to the hospital just before midnight Wednesday, Zuma's office said. 
 
 It's the second time this month he has been hospitalized. More than two weeks ago, he was taken to a hospital for what officials described as a routine checkup. 
 
 Mandela has become increasingly frail over the years, and has not appeared in public since South Africa hosted the World Cup in 2010. 
 
 Photos: The evolution of Nelson Mandela Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Nelson Mandela, the prisoner-turned-president who reconciled South Africa after the end of apartheid, died on December 5, 2013. He was 95. Hide Caption 1 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Mandela became president of the African National Congress Youth League in 1951. Hide Caption 2 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Mandela poses for a photo, circa 1950. Hide Caption 3 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Mandela poses in boxing gloves in 1952. Hide Caption 4 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Mandela in the office of Mandela & Tambo, a law practice set up in Johannesburg by Mandela and Oliver Tambo to provide free or affordable legal representation to black South Africans. Hide Caption 5 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – From left: Patrick Molaoa, Robert Resha and Mandela walk to the courtroom for their treason trial in Johannesburg. Hide Caption 6 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Nelson and Winnie Mandela raise their fists to salute a cheering crowd upon his 1990 release from Victor Verster Prison. He was still as upright and proud, he would say, as the day he walked into prison 27 years before. Hide Caption 7 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – A jubilant South African holds up a newspaper announcing Mandela's release from prison at an ANC rally in Soweto on February 11, 1990. Two days later, more than 100,000 people attended a rally celebrating his release from jail. Hide Caption 8 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Mandela and Zambian President Kenneth Kaunda arrive at an ANC rally on March 3, 1990, in Lusaka, Zambia. Mandela was elected president of the ANC the next year. Hide Caption 9 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – After his release in 1990, Mandela embarked on a world tour, meeting U.S. President George H.W. Bush at the White House in June. Hide Caption 10 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – At his Soweto home on July 18, 1990, Mandela blows out the candles on his 72nd birthday cake. It was the first birthday he celebrated as a free man since the 1960s. Hide Caption 11 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Mandela and his wife react to supporters during a visit to Brazil at the governor's palace in Rio De Janeiro, on August 1, 1991. Hide Caption 12 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – South African President Frederik de Klerk, right, and Mandela shared a Nobel Peace Prize in 1993 for their work to secure a peaceful transition from apartheid rule. Hide Caption 13 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Mandela votes for the first time in his life on March 26, 1994. Hide Caption 14 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – On April 27, 1994, a long line of people snake toward a polling station in the black township of Soweto outside of Johannesburg in the nation's first all-race elections. Hide Caption 15 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Mandela in Mmabatho for an election rally on March 15, 1994. Hide Caption 16 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Mandela was elected president in the first open election in South African history on April 29, 1994. He's pictured here taking the oath at his inauguration in May, becoming the nation's first black president. Hide Caption 17 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Mandela, left, cheers as Springbok Rugby captain Francois Pienaar holds the Webb Ellis trophy high after winning the World Cup Rugby Championship in Johannesburg on June 24, 1995. Hide Caption 18 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – After one term as president, Mandela stepped down. Thabo Mvuyelwa Mbeki, at right, was sworn in as his replacement in June 1999. Hide Caption 19 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Mandela sits outside his former prison cell on Robben Island on November 28, 2003, ahead of his AIDS benefit concert at Green Point Stadium in Cape Town. He was sent to the infamous prison five miles off the coast of South Africa, where he spent 18 of his 27 years behind bars. Hide Caption 20 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Mandela shows something to a group of international journalists visiting the Nelson Mandela Foundation in Johannesburg in May 2004. Hide Caption 21 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Mandela sits with his wife, Graca Machel, and his grandchildren at his son's funeral on January 15, 2005. He disclosed that his son, Makgatho Lewanika Mandela, had died of AIDS and said the disease should be given publicity so people would stop viewing it as extraordinary. Hide Caption 22 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – The "46664 Arctic" benefit concert was held in Tromso, Norway, on June 11, 2005. 46664 was Mandela's identification number in prison. Here, artists who performed at the event surround him. Hide Caption 23 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Mandela attends an HIV/AIDs concert in Johannesburg on February 17, 2005. Hide Caption 24 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Former U.S. President Bill Clinton leans down to whisper to former South African President Nelson Mandela during a visit to the Nelson Mandela Foundation on July 19, 2007, in Johannesburg. Hide Caption 25 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – A bronze statue of Mandela was unveiled in Parliament Square in London on August 29, 2007. The 9-foot statue faces the Houses of Parliament. Hide Caption 26 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Mandela leaves the InterContinental Hotel after a photoshoot with celebrity photographer Terry O'Neil on June 26, 2008, in London. Hide Caption 27 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Mandela meets in 2009 with international children as part of his 46664 Foundation. Hide Caption 28 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Nelson Mandela and his third wife, Graca Machel, arrive at the 2010 World Cup before the final match between Netherlands and Spain on July 11, 2010, at Soccer City Stadium in Soweto. Hide Caption 29 of 30 Photos: The evolution of Nelson Mandela The evolution of Nelson Mandela – Then-U.S. Secretary of State Hillary Clinton meets with Mandela at his home in Qunu, South Africa, on August 6, 2012. Hide Caption 30 of 30 
 
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 "Doctors are attending to him, ensuring that he has the best possible expert medical treatment and comfort," Zuma's office said in an earlier statement Thursday. 
 
 "We appeal to the people of South Africa and the world to pray for our beloved Madiba and his family, and to keep them in their thoughts." 
 
 "Madiba" is Mandela's clan name, which is widely used in the nation. 
 
 Josh Earnest, White House deputy press secretary, said President Barack Obama is being updated on Mandela's health. 
 
 "Our thoughts and prayers go out to the former president and his family," Earnest said. 
 
 Zuma's office did not say to which hospital he was admitted, but renewed calls for his privacy. 
 
 Mandela has been treated for the ailment before. He underwent treatment for a lung infection and had surgery to remove gallstones over the Christmas holiday in 2012, one of his longest hospital stays since his release from prison in 1990. 
 
 He suffered from tuberculosis during his imprisonment and has battled respiratory infections over the years. He also was treated for an acute respiratory infection in 2011, among other recurrent bouts of illness. 
 
 Considered the founding father of South Africa's democracy, Mandela became an international figure when he endured 27 years in prison for fighting apartheid, the country's system of racial segregation. 
 
 In 1993, he and then-South African President F.W. de Klerk jointly won the Nobel Peace Prize. 
 
 Mandela was elected president a year later, serving only one term, as he had promised. 
 
 Despite only rare public appearances in recent years, he retains his popularity and is considered a hero of democracy in the nation. Last year, South Africa launched a new batch of banknotes with a picture of a smiling Mandela on the front, a testament to his iconic status. 
 
 Mandela's impact extends far beyond South African borders. After he left office, he was involved in mediating conflicts from Africa to the Middle East.
– Weeks after returning home from the hospital, Nelson Mandela was admitted again last night for a lung infection. South African president Jacob Zuma is calling on the world to offer its support to the 94-year-old icon, NBC News reports: "We appeal to the people of South Africa and the world to pray for our beloved Madiba and his family and to keep them in their thoughts," Zuma said. "We have full confidence in the medical team and know that they will do everything possible to ensure recovery." Mandela, who CNN notes was conscious when admitted last night, was hospitalized for weeks in December with a lung infection and has battled respiratory problems for years.