Gastaldi, Geronimo an Italian prelate, was born at Genoa in the early part of the 17th century, of an ancient Genoese family. He embraced the ecclesiastical calling, and went to Rome. In 1656, Gastaldi, already a prelate, was designated for the perilous position of general commissary of the hospitals, and was afterwards appointed general commissioner of public health, and so faithfully did he perform his duties that he secured the archbishopric of Benevenito, the cardinalate,. and the legation to Bologna. Several monuments erected at his expense at Rome and Benevento attest his charity and munificence. He gave his observations concerning contagious diseases in a work which was published at Bologna in 1684, the year previous to. his death, suggesting certain precautions and remedies. See Hoefer, Nouv. Biog. Generale, s.v.