Per 
Item #: SCP-4237
Object Class: Safe
Special Containment Procedures: every SCP-4237 colony must be contained inside a stantard 500ml blood bag, mixed with pure and fresh blood plasma extracted from any human being with AB blood type. Any blood bag containing a colony of SCP-4237 must be locked inside a vaccum locked refrigerated vault, in a temperature between 25K to 40K, the vault must be decontaminated every 10 days.
Description: SCP-4237 is a colony of erythrocytes found in the blood of a citizen from ███████ ████, Brazil. The colony was found after a group of foundation cientists on a undercover mission were secretly studying the population of ███████ ████, to see if the soil extremely rich in iron and other minenals caused any type of mutation in the organism of humans that live in the area. After some weeks of research, the cientists started to run blood exams in the population as a last resource before ending the research. When the cientists started to study the results, they found a estrange new type of erythrocytes, that changes his aglutinogen on it's own, meaning that, the blood extracted from the population of the city was constantly changing it's own blood type, this kind of mutation has never been reported in any country, and so, was tought to be impossible, due to a specific code in the human DNA.
The cientists found, that those erythrocytes carry some new tipe of nucleic acid, that float on the cell's cytoplasm without needing any type Of nucleus in the cell. That nucleic acid could not be used to clone the cell, since it's not a normal DNA. The mutation seems to happen 2 days after the cell is generated, and then, changing the aglutinogen every 20 hours.
These cells show some kind of defense mechanism, they attack any other erythrocytes that doesn´t show the mutation, so SCP-4237 can´t be used in donation even if the receiver is a AB type.
The mutation seems to exist only in the blood cells, since no other anomalies were found in the body of the population
After the discovery of the anomalous erythrocytes, the foundation built a mobile temporary Base and set a circular exclusion zone with a 20km radius around the city, any satelite picture from the city was terminated and signal blockers were installed in all the zone, isolating the city. The city must remain in lockdown state until the research is done, then the city will be completely terminated using any necessary means to do so.
Addendum: Any invader or escapee must be physically removed.
