P. gastrotena is an infectious pathogen that is located in the digestive systems of many multicellular creatures, primarily those of Carpotesta luceremundare and its descendants. It attacks the inner organs of the host, feeding on the cytoplasm of the cells that compose the internal organs and killing the cell in the process. Their thick cell membrane is specially adapted to resist the digestive enzymes of the host, enabling it to survive and reproduce better in the digestive system. P. gastrotena can only infect an organism via consumption. This either occurs when a filter-feeder consumes some P. gastrotena suspended in the water or when another creature consumes the body of an infected species. Once it is inside of the gut, P. gastrotena will begin to feed on the cells lining the gut. While a handful of P. gastrotena may not be immediately harmful to the infected individual due to the infected creature’s cells continually replacing the dead ones, a P. gastrotena infection can quickly reach damaging levels, with large numbers of P. gastrotena feeding on living cells faster than the infected host’s body can replace them.

There are 5 basic stages to a P. gastrotena infection. In stage one, the pathogen has just entered the host. There are no visible effects at this stage, and in some cases, the infection may not ever advance past stage one.

In stage two, the infection is beginning to near dangerous levels. The infected organism has an increased appetite at this stage, necessitated by the need to ingest enough nutrients and material to replace the massive numbers of dead cells.

In stage three, the infection has just reached the point of no return. The pathogen has begun to kill cells faster than the host’s body can replace them. An increased appetite, slight discoloration, and slight decrease in activity are all indicators of this stage.

In stage four, the infection has spread beyond the gastrointestinal system of the infected organism and to the rest of the body. By this stage, the digestive system is almost useless, large parts of it having been reduced to a near-slurry. Lack of appetite, listless behavior, discoloration, and bloating are all indications of this stage. Towards the end of stage four, large patches of dead tissue may be visible from the outside of the organism.

In stage five, the infected organism is most dangerous. Mostly decaying, necrotic tissue, the organism is a vector for P. gastrotena infection. Due to the advanced stage of decay in the host, stage five is the shortest and always ends in death.