Patient Zero

Patient Zero
Gabriel Gray, Chandra Suresh's supposed Patient Zero
First mentioned:	Genesis

In medicine, Patient Zero (also called the "index case") refers to the original source of an outbreak of a contagious illness within a population (that is, the origin of the outbreak from whom all other infections are ultimately derived) or to the most significant case within the population.

In fact, Chandra had already assembled a list of identified evolved humans, and Sylar, then known as Gabriel Gray, was the first he chose to contact. His reasons for choosing Gray as his first subject are unknown.

About

Genesis

Chandra Suresh told his son Mohinder two days prior that he believed he was close to discovering the "Patient Zero" for his theories about new human evolutionary traits, and had tracked him down to Queens, New York.

Don't Look Back

While searching for Mohinder the lizard, Eden and Mohinder overhear an answering machine message left for Chandra by Sylar. Mohinder tells Eden that he found a tape of a conversation between his father and a man named Sylar, whom Mohinder claims his father believed was Patient Zero.

Memorable Quotes

"I found a tape of a conversation my father had with a man named Sylar, a man he believed was Patient Zero."

- Mohinder Suresh (Don't Look Back)

Notes

• It is presently unclear why, if Chandra had already met Gabriel Gray six months prior and witnessed him using telekinesis, he told Mohinder he was "close" to finding his "Patient Zero".
• Chandra's actions in Six Months Ago and the fact that he had already identified many other potential evolved humans (and even identified one in Madras—Sanjog Iyer) indicate that it's quite likely that Sylar was merely the first evolved human he contacted in New York. If by "Patient Zero" Chandra merely meant that Sylar was his first confirmed case, then he is using the term in quite a different sense than it was intended.
• It is possible that his use of the term "Patient Zero" might have some greater significance. Typically, referring to someone as "Patient Zero" would imply that they are the earliest case or the case from which other cases developed. Given that there are people on the list who are quite likely older than Sylar, it's unlikley that Suresh meant that Sylar was the first individual to develop powers or was the earliest-born individual with powers. However, it's still possible, though unlikely, that Chandra believed Sylar was pathologically responsible for others developing their powers.