Patient Zero

Patient Zero is a unique spore carrier found in the Big MT.

Background
The origin of this creature comes from a human patient that mutated when the B. mordicana fungus, later used in Vault 22, infected them. They were considered a failed experiment by the Big MT scientists, and the body was left alone. However, when the scientists returned to the laboratory, the body of Patient Zero had disappeared and now can be found at the X-22 botanical garden.

Gameplay attributes
Spore carriers are quick and use melee attacks. Spore carriers have some characteristics of trogs from Fallout 3 The Pitt add-on. If they are not killed quickly they explode and deal large amounts of damage, breaking limbs, and giving a large dose of radiation. When they are hiding in vegetation they are hard to spot and will not appear on the player's compass nor be targeted via V.A.T.S. until they get up.

Walking right past unexplored vegetation might result in an unpleasant scare. Spore carriers are also known for sneaking up on the player. However, the player will see their health meter if he hits them with an area weapon like a flamer or grenade, immediately informing you of their presence. Weapons that use fire (such as the flamer) or weapons with large spreads (such as the riot shotgun) are extremely effective against them.

Upon detecting the player, the spore carrier will raise themselves out of the large growth of vegetation where they hide and will let off a growl in a similar manner to that of feral ghouls, albeit louder and with greater ferocity.

While a spore carrier is getting up or sleeping, players in sneak mode who manually attack the spore carrier will get a Sneak Attack Critical. Combined with a decently powerful weapon, such preemptive strikes can often kill the spore carrier before it ever becomes a need for concern.

Appearances
Patient Zero appears only in the Fallout: New Vegas add-on Old World Blues.

Behind the scenes
The term "Patient Zero" was originally used to describe the individual initially believed responsible for introducing the virus responsible for AIDS to the United States, although the designation was later repudiated. It has since been genericised to refer to the first described instance or "index case" of any medical condition, in which case it is used in decapitalized form.