Los Iluminados existed in Europe for an indeterminite length of time, though had a presense in Spain for several centuries. The first Castellan of the region, in fierce opposition to the religion's teachings, launched a violent repression on its activities.
In modern times, the region where the Plagas had been sealed had been re-opened by Ramon Salazar, 8th Castellan of the region and a follower of Osmund Saddler, the current leader of Los Illuminados. Though the Plagas had been sealed away for centuries, their fossilized remains contained long-dormant spores that were able to infect the local inhabitants who excavated them, essentially ressurrecting the species. Likely using these first Plagas, Saddler perfected the ability to reproduce the organism and took to implanting Plaga eggs into new hosts.
The cult's followers were soon implanted with Plagas along with much of the local population who had joined the cult. Saddler himself was implanted with a dominant-strain Plaga and as such has direct control over the others, using lieutenants with similarly augmented Plagas to monitor and direct the Ganados on the ground.
The villagers then returned to life as normal as they could, farming, attending cult services at the local church, acting as guards for Salazar's castle or working the mines while the cult zealots engaged in dark rituals and sacrifices in the name of Saddler.
Saddler, a malevolent fanatic who harboured a deep hatred for the United States which he saw as the centre of corruption and impurity in human society, saw the re-emergence of Las Plagas as a means of spreading enlightenment to all of humanity. Investing large sums of money in revolutionary new medical technology and genetic research material that had become widespread on the global black market since the Umbrella Trials, Los Illuminados acquired the means of enhancing the Plagas and developing their own bio-organic weapons using Plaga genes.
Some time before Autumn 2004, American agent Jack Krauser, while secretly working for Albert Wesker, arrived at the village in search of the parasite. He was later used to kidnap Ashley Graham, daughter of U.S. President Graham, as part of an Iluminados plot to do no less than take over the entire world by infecting Ashley and returning her to her father in order to influence the United States' executive branch. Saddler noted, however, that in order to take over the US, the parasites would need to spread to those with influence over the President's decisions - Congress; the Department of Justice; military government agencies and large private companies.
Plan B was to use Saddler's own militia to infiltrate the United States and sow discord from within, likely gaining converts to Los Iluminados as they went. Ada Wong, an agent for "the 3rd Organization" and subordinate to Wesker, destabilized "Plan B" when she sank the militia's warship docked within the cult's island stronghold.
Thanks to US Secret Service agent Leon S. Kennedy, Saddler's plans for world domination were thwarted and the Los Illuminados are believed to have been completely destroyed.
Below is a complete list of all B.O.W.'s utilized by the Illuminados.