Doctor originally from Germany shifted to Pakistan in 1960 and started her fight against leprosy resulted in end of disease in Pakistan. In 1989, Dr Ruth was presented the Hilal-i-Pakistan.
Dr Ruth Pfau passed away early Thursday morning after a long illness at the age of 87. "Pakistani nation salutes Dr. Pfau and her great tradition to serve humanity will be continued", the President stated.
Pfau first witnessed leprosy, an infectious disease that affects the skin and other organs of the body, in Karachi.
Pfau trained as a doctor in her youth and went on to join a Catholic sisterhood.
From then onwards she dedicated herself to the fight against the disease, and by 1996 it was declared to have been brought under control.
Pfau served as an adviser to the Pakistani government for the eradication of leprosy between 1975 and 1980. The country's Dawn newspaper reports that a year ago, just 531 patients were in treatment for leprosy nationwide - down from 19,398 in the early 1980s.
Tributes are pouring in for a German nun who spent more than half a century in Pakistan battling leprosy and helping the country's most vulnerable people.
Her death drew messages of condolences from all sections of Pakistani society, with many comparing her passing to that of the philanthropist Abdul Sattar Edhi, who passed away a year ago. And she ultimately came to enjoy a celebrity in Pakistan on par with another nun known the world over for her work with the sick and the poor: Mother Teresa. She was likewise granted with the Staufer Medal.
Saddened to learn of Dr Ruth Pfau's passing.
And as Pfau told the BBC, she never forgot that young man she met on her first stay in Karachi, the patient who crawled toward her in the dirt because he'd been convinced there was nothing more for him than that.