Item #: SCP-1003
Object Class: Keter
Special Containment Procedures: The Foundation currently has 10 instances of SCP-1003-2 (designated SCP-1003-2-a-k) in its possession, all of which are held in separate heavily guarded high-security cells at Bio-Research Area 13. All personnel at Bio-Research Area 13 are to undergo regular compulsory testing for signs of SCP-1003 infection. Personnel wishing to access SCP-1003-2-a-k may only do so for the express purpose of research, must have Level 4 security clearance, and must have written permission from O5-█ beforehand. They are to wear biohazard suits when entering SCP-1003-2-a-k's cells, and go through an intensive disinfection process afterwards. No animals of the order Carnivora are to be allowed at Bio-Research Area 13 under any circumstances.
Description: SCP-1003-1 is an adult tapeworm of the species Echinococcus granulosus, known for causing hydatid disease. Like others of its species, SCP-1003-1 inhabits the small intestines of carnivores (typically canids), where it produces eggs that are passed in the host's faeces. The eggs can survive up to ██ years in the outside environment.
When the eggs enter the gastrointestinal tract of a human subject (hereby designated the intermediate host) via consumption of contaminated food, they hatch into larvae, which burrow into the host's tissues. It is at this stage that SCP-1003's anomolous properties begin to manifest. Instead of developing into cysts, the larvae develop into creatures which resemble human embryos (hereby designated SCP-1003-2). The vast majority of SCP-1003-2 specimens die before they have a chance to develop. Those that survive are usually those that are embedded in nutrient-rich tissue, such as hepatic tissue. As they develop, they absorb nutrients from the surrounding tissue, which often causes problems for the intermediate host.
SCP-1003-2's development mostly follows the pattern of normal human prenatal development, but at a faster rate. By 8 weeks, it is as mature as a 3-week-old neonate, although it is similar in size to an 8-week-old embryo (approximately 13-16 cm). Once it has reached this stage, it will actively consume the intermediate host from within using sharp, hooked teeth. SCP-1003-2 growth is accelerated to an even greater extent as it is doing this. By the time it has fully consumed the intermediate host (usually after ███ minutes or so), it will have developed into a child. The physical age of the child typically ranges from 10 months to 11 years, depending on the mass of the intermediate host, though in extreme cases (where the intermediate host is morbidly obese) it can be as high as 13-15 years.
Once SCP-1003-2 is finished, it will lose its hooked teeth, along with its cannibalistic tendencies, from whereon it will be functionally indistinguishable from a human in every respect, with no knowledge or memory of having been a parasite. It will even possess learned skills (e.g. language) that would be expected of a child its apparent age, despite there being no way it could have learned them. Instances of SCP-1003-2 are usually taken into orphanages and sometimes adopted by foster parents. Their only anomalous properties at this stage are that their DNA is somehow still identical to that of Echinococcus granulosus, and that their body fluids (including sweat and saliva) contain tapeworm protoscolex, which infect carnivores and develop into SCP-1003-1, thus continuing the cycle.
Addendum: Testing of SCP-1003 with animals such as cattle and sheep (which are common intermediate hosts of Echinococcus granulosus) have found that its anomalous properties only manifest in humans, and in all other cases, its life cycle is normal and causes hydatid disease in the intermediate host.