The Cordyceps Brain Infection is a mutated form of Ophiocordyceps unilateralis that has developed to infect humans. This virus functions similar to a zombie virus, and Infected can live up to 20 years and go through 3 or 4 stages. Patient Zero in Tijuana, Mexico is infected via mushrooms contaminated with the virus in September 2015. The virus is airborne, but only via spores, which are easy to see. The virus essentially controls victims' minds, and their humanity is completely lost by Stage 2, which begins 1 week to 1 month after the onset of infection.
Time from infection to zombification by method of transmission:
Bite: 8 hours - 12 hours (depending on location within the body)
Spores: 12 hours - 24 hours (depending on amount inhaled)
Food: 24 hours - 3 days (depending on amount of contaminated food eaten)
September 7: Patient Zero eats the mushrooms contaminated with the virus.
September 8: Patient Zero crosses the border into California.
September 9: Patient Zero crosses back into Mexico. He begins to turn while waiting in line to be processed by Mexican officials. Near the front of the line, he gets out of his car and starts to run around infecting people. Before he was shot by U.S Customs and Border Protection agents, he had infected 17 people.
These people include: 6 Mexican immigration officials, 4 U.S immigration officials and 7 pedestrians who were waiting in the pedestrian crossing line. After the "crazy man" is shot, all bite victims are brought to a hospital near San Diego and the San Ysidro / Tijuana crossing is declared closed indefinetely.