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.

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.

One Giant Leap

Eden discovers Chandra's journal hidden in Chandra's laptop after Mohinder throws it across the apartment. She then discovers Sylar's address in Queens—where Chandra stated he had located Patient Zero.

Six Months Ago

Chandra Suresh arrives in New York City and meets with Gabriel Gray, a name from his list of identified potential evolved humans. After some initial testing, Chandra is disappointed, and believes Gabriel to be genetically normal. Later, however, Gabriel returns to Chandra's apartment and displays the telekinetic abilities that he gained from Brian Davis, becoming the first evolved human Chandra meets in New York.

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

• By the time Chandra told Mohinder he was close to finding his Patient Zero, he 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. 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 while he was still in Madras—Sanjog Iyer) indicate that it's quite likely that Sylar was merely the first evolved human he contacted in New York City. 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 unlikely 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.