- "Sir, he's not using a weapon, he's infected."
- ―Jemma Simmons
The Chitauri Virus is a lethal affliction originating from the Chitauri.
The Chitauri virus is unique, compared to Earthly viruses, in that it does not spread through microscopic pathogens, but through electrostatic shock. Once infected, the victim would experience severe head pains and their body would give off weak electrostatic fields, causing any nearby magnetic materials to levitate. Eventually, the infection would kill the victim in the form of an electrostatic implosion in the brain.
Over time, the Chitauri apparently adapted to the infection. After the Battle of New York, a Chitauri Helmet was recovered by fireman Tony Diaz and taken back to his fire department's firehouse in Wrigley, Pennsylvania. Unknown to Diaz, the helmet actually carried traces of the Chitauri virus; Diaz and two of his fellow firemen, Adam Cross and Frank Whalen, were afflicted with the virus after cleaning the helmet.
All three firemen died, and soon after, S.H.I.E.L.D. scientist Jemma Simmons became infected after examining Cross' contaminated corpse. Fortunately, she was able to create an antiserum and was cured. The helmet was then taken to the Sandbox where it was picked up by Agent Felix Blake.