AMBANJA, APOSTOLIC PREFECTURE of. - Located in insular Africa, it derives from the prefecture of Isola Santa Maria, Nossi-Bè and Mayorte (the latter belonging to the Comoro group), and was erected in 1848, by detachment from the apostolic vicariate of Madagascar, and enlarged (1858) by the annexation of the remaining Comoros (La Grande-Comore, Anjouan, Mohéli). Once Isola Santa Maria had been definitively detached from it (1898), the jurisdiction was extended to the districts of Sambirano and Maromandia (Madagascar), ceded by the vicariate of Diego Suarez; on 2 February 1932, the prefecture was entrusted to the Capuchins of Alsace, its territorial boundaries being at the same time specified. Its name was changed to that of A. by decree of 14 June 1938.
The area of the territory is 14,780 sq. km., and the total population 240,000 inhabitants, namely 128,155 Muslims, 64,233 pagans, 4,936 Catholics (of whom 3,723 are indigenous), and 821 catechumens. The missionary apostolate, entrusted to 16 Capuchin priests and two lay brothers, and to three Franciscan Sisters of Calais, is carried on effectively, especially among the Malagasy of the Madagascan districts.