By CHRISTOPHER TORCHIA FILE – In this June 17, 2010 file photo, former South African President Nelson Mandela leaves the chapel after attending the funeral of his great-granddaughter Zenani Mandela in Johannesburg, South Africa. The South African presidency says Nelson Mandela was re-admitted to hospital with a recurrence of a lung infection Thursday March 28, 2013. (AP Photo/Siphiwe Sibeko, Pool, File) OHANNESBURG (AP) — South Africa’s presidency says 94-year-old Nelson Mandela is responding positively to hospital treatment for a recurring lung infection. The office of President Jacob Zuma also said in a statement Thursday that the former president and anti-apartheid leader remains under observation. Mandela was admitted late Wednesday to a hospital in Pretoria, the South African capital. Mandela contracted tuberculosis during his 27-year imprisonment for fighting white racist rule in South Africa. He has repeatedly had lung problems.