How did the zombies get infected in dead rising

The zombies manifested because in Santa Cabaza a science group was researching a way to mass produce cattle to accommodate for the consumption of American that eat meat daily. One day a parasitic larva that had evolved into a wasp carrying the parasite escaped and infected the village of Santa Cabaza. The government sent the Special Forces to clean up the infected, 2 survivors where left, Carlito and Izabella keyes. The media said that it was a drug trade operation, enraged by the cover up, Carlito got some wasps with the hormone and took it to Colorado and set it loose on the people of Willamette in the form of revenge. To safeguard his plan he took several measures. If he was backed into a corner he would blow up the mall with a nuke with parasitic larva that would shoot into the atmosphere so everyone would be infected but his most devious plan was come if all failed. Before the Willamette crisis he adopted 50 orphans and infected them and gave them all a suppressant to temporarily stop the larva infecton and sent them all over the country - essentially ticking time bomb.