Because of the severe food shortage immediately after the war, giant African snails became a protein source of desperation. They were ditched as soon as the food situation improved, however. The Okinawans also did not have a snail-eating custom. So the snails were simply let go that had resulted in an explosive growth as they had no natural enemies in Okinawa.
The outbreaks in Ogasawara Islands and Okinawa became so bad that traveling cars regularly crushed them on highways. Worse, damage to agriculture was enormous. So snails by the truckloads were collected and destroyed. Then in 1969, cases of eosinophilic meningoencephalitis were reported in Okinawa. Extermination of the snails, carriers of the parasite Angiostrongylus (Angiostrongylus cantonensis), started post-haste.
By 1985, routine removal in Okinawa Prefecture had seen a decline of the snail population, although not totally gone. Curiously, in Chichi-jima 父島 of the Ogasawara Islands, the snails totally disappeared in around 1989, even though those on Haha-jima 母島 remained alive and well. Cause of the Chichijima snail depletion was unknown, possibly owing to the arrival of some new predators.