The "Omega Strain", as its name implies, was the final version of Syphon Filter. The virus was the main plot device for the fourth Syphon Filter game.
Origins
DNA codes that were acquired from Ivankov's computer system in the Chechen terrorist headquarters in Kiev, Ukraine suggested Dr. Nikolai Jandran was responsible for creating the Omega Strain. The virus was essentially a hybrid of the original Syphon Filter combined with Bovine Spongiform Encephalitis (more commonly known as mad cow disease). It was one of the pathogens that PHARCOM considered developing but ultimately abandoned since gestation required decades. The Omega Strain was spread via water and assaults the central nervous system upon entering a victim, destroying brain tissue similarly to how AIDS attacks the immune system. Fortunately, Lawrence Mujari and a couple of IPCA personnel had some limited protection from the original Syphon Filter virus, provided by a vaccine.