(Covers information from Anderson's universe)
Las Plagas was a parasitic organism developed by the Umbrella Corporation and produced at their Umbrella Prime facility in Siberia until its destruction late into the Global T-virus pandemic. It was able to enhance human bodies, granting superhuman strength. It was also able to affect the rate of cellular regeneration, allowing the hosts to recover from injuries much quicker, including head injuries. Umbrella Prime experimented with the use of Las Plagas on the Majini Undead, an increasingly-common Undead mutation. This resulted in the Las Plagas Undead, who were now able to follow orders. After this was found, Las Plagas Undead were trained as soldiers in the event of an attack by external forces.