Dragon Ball Z: Invasion

5 years after Majin Buu was defeated, there is peace and tranquility on Earth. Both Goku & Vegeta have reached new level of strengths. Even Gohan has been training hard to push the limits of his mystic form alongside his job.
Goku had been training on King Kai's planet. Vegeta however hadn't been able to keep up with his training for some time. After persistent requests by Bulma, he agreed to visit the doctor with her.
To their utter shock, Vegeta was diagnosed with a strange disease. The doctors said they hadn't seen any such virus ever before. Despite his efforts, Vegeta had to stay in the hospital for further research and possible treatment.
At this time, a new threat arrives on Earth. Can the Z warriors see this threat off?

NOTE: I own no rights to the Dragon Ball franchise. This is a work of fan fiction and is not being done for any profit.
According to this story, the 25th World Martial Art Tournament that happened at the end of Dragon Ball Z is not canon. Battle of Gods, Resurrection 'F' (Dragon Ball Super) and Dragon Ball GT aren't canon either.