The Disease Waveform known simply as "The Tapeworm Cosmic" is an extradimensional, endosymbiotic parasite that came from a Universe which existed prior to Earth-616, whether it is the same Universe that
originated from is not known. What is known however about the parasites is that they use beings like Galactus as hosts.
Once they attach themselves to a host they immediately begin the process of intensifying their hosts appetite, amplifying their metabolism and even begin rapidly accelerating the burn rate on their hosts
which in turn intensifies the hosts appetite even further.
Recently after weeks of experiencing extremely severe hunger pangs
, the estranged daughter of Galactus, performed an examination on herself only to discover that she is carrying one of the parasites.
After several failed attempts to rid herself of the rapidly growing parasite she was forced to call upon her Father for help.
However, due to his unavailability Galacta was forced to seek out the answer to the cure on her own and as she did the hunger grew worse and worse.
Eventually, Galacta managed to find the "cure" for her ailment in the form of The Ultimate Nullifier which she planned to use before the overwhelming hunger could turn her into a monster like her Father.
But before she could pull the trigger, her Father confronted her and told her that she had completely misidentified the nature of the Tapeworm Cosmic and explained that Galacta herself had once been an entity similar to the Tapeworm Cosmic which, like the one in Galacta, had spontaneously generated itself within his very own Power Cosmic fieldweave.
In other words, she was not infected with some insidious parasite seeking to turn her into the very planet-ravaging monster she promised herself that she would never become, but that she was actually pregnant and going to become a Mother.