The Chitauri Virus is a lethal affliction originating from the Chitauri.
- "We're dealing with a propagating virus, which means–"
"The virus can move from person to person."
"Exactly! And that's the most exciting part, how it spreads, not through the air or through direct fluid transfer but through electric static shock. It's like nothing we've ever seen on Earth. I didn't think it possible a virus could alter its host's molecular density and polarity."
- ―Jemma Simmons and Phil Coulson[src]
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, creating a natural immunity.
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.
Creating A Cure
- "It's born from alien DNA. There's no one to create an antiserum from because no one's actually survived this, except... the Chitauri."
"The Chitauri. Well, the minky bastard who actually wore the helmet had the virus."
"Yeah, and managed to survive without ever emitting an electrostatic pulse because–"
"It was immune."
- ―Jemma Simmons and Leo Fitz[src]
All three firemen died, and soon after, S.H.I.E.L.D. scientist Jemma Simmons became infected after examining Adam Cross' contaminated corpse. Fortunately, Simmons 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.