TOKYO (Reuters) - A television cartoon based on the popular video game "Pocket Monsters" triggered seizures in hundreds of children around Japan on Tuesday night, with many rushed to hospital. Japanese media said at least 550 schoolchildren suffered convulsions, vomiting and other symptoms while watching the cartoon. Kyodo news agency said 19 children were badly enough affected to have to remain in hospital. The children came down with the symptoms about 20 minutes into the 30-minute long cartoon. The offending scene was one in which a bright red explosion filled the screen. The ages of the children ranged from three upwards. The TV animation cartoon, called "Pokemon", features some of the "Pocket Monsters" characters in a video game produced by toy maker Nintendo Co <7974.OS>. Kyodo said some children reportedly said they felt bad and had vision problems after seeing "Pikachu", one of the most popular characters, flash its eyes during the cartoon. The cartoon has been broadcast on 37 TV stations nationwide since April and has the highest audience rating in the Tokyo area for its time slot. According to the reports, Tuesday`s programme featured a scene with an explosion of a "vaccine bomb" to destroy a computer virus. That was followed by the flashing of a red light for five seconds. Psychologist Rika Kayama said the phenomenon might be an epileptic effect induced by flashing light, known as photosensitive epilepsy or group hysterics Kayama said one piece of research suggests that four percent of epilepsy patients have photosensitive epilepsy, but only multiple flashes of light can cause the reaction. A spokesman for Nintendo said it was waiting for a full report from TV Tokyo on the animation. Nintendo said it issues a health warning on its video software.