Pop diva Madonna, spending her fourth day in the southern African country of Malawi on Thursday, picked up ailing children and joked with them when she visited an overcrowded children’s ward in Blantyre, the country’s largest city.

“Muli bwanji? (How are you?)” she greeted them in Malawi’s main language, Chichewa.

Madonna, with her son, Rocco, went to Queen Elizabeth Central Hospital, which she has been supporting for five years through its chief pediatrician, Dr. Eric Borgstein.

“Eric Borgstein is a hero of mine” said Madonna. “He is doing a wonderful job.”

The ward performs at least 500 surgeries per year on poor children, said Borgstein.

Madonna is the largest individual donor to the hospital and funds programs run by Borgstein that include treating children with cancer, said Trevor Neilson, president of the Global Philanthropy Group that is managing Madonna’s projects in Malawi.

Born and raised in Malawi, Borgstein said he studied medicine at the University of Groningen in the Netherlands before to returning to his home country. Borgstein said he has been working in children’s health for 15 years, treating up to 40 patients daily. Malawi has only three pediatric surgeons, said Borgstein.

He is currently a partner of Raising Malawi, the non-profit organization Madonna co-founded with Michael Berg in 2006 to help Malawian children.

On Friday, Madonna visited Consol Homes Orphan Care Centre, 50 kilometers (31 miles) outside the capital, Lilongwe.