From Santa Maria in Via Lata, Fortunatus’ relics were translated to Casei Gerola in 1765, as a gift to the church there from the Holy See. Casei Gerola, in the province of Pavia, was an important village of the diocese of Tortona, which had close ties to the papacy. His relics were kept in an urn; Fortunatus’ skull was crushed, indicating the cause of death to be a fatal blow to the head.
Another source states that he was venerated in the catacombs of Saint Priscilla in Rome until 1600, when some of his relics were translated to Turbigo, although his relics were also claimed by Casei from 1700 onwards. There may have been two saints with the same name of Fortunatus. Some of his relics are also claimed by the parish of Lonate Pozzolo.
He was proclaimed patron saint of Pantelleria after he is believed to have aided the island through miraculous intervention during an earthquake in 1831 and a seaquake in 1891. A procession in honor of the saint is held on October 16; a statue of the saint is carried on a boat.