Beauveria mordicana was originally an entomopathogenic fungus designed for pest control. When a pest is exposed to the fungal spores, the fungus infests it and begins to colonize the host body. The host eventually dies due to failure of body functions, as the colony expands through its body. However, the dead body continues to be controlled by the fungal colony, allowing it to move around and infect more pests by spraying spores around the host body. While effective in the long term, it still takes between 10 to 20 days to kill its prey and achieves limited effectiveness when dealing with unsocial pests. The fungus was originally developed at the X-22 botanical garden at Big MT, though the technology was eventually shared with Vault-Tec, to enable botanical experiments at Vault 22.
As with many technologies coming out of Big MT, the fungus was a Pandora's box. Once the Vault scientists began experimentation with the fungus, they effectively signed their death warrant. While ostensibly designed to provide effective means of long-term pest control, the fungus was perfectly capable of infecting human bodies. Fungal spores gradually spread through the Vault, slowly infecting the population. The first confirmed infection was Dr. Harrison Peters, who also provided insight into the development of the infection. It begins with pneumonia as the fungus invades the lungs, eventually transforming into chills, a fever and a terrible racking cough. The fungal colony causes the body to actively reject anti-fungal treatments, leading to death due to organ failure. As with smaller pests, the fungal colony continues to grow and develop. Eventually, it spreads far enough to establish control over the deceased person's body, becoming a highly aggressive spore carrier, a mindless beast whose sole purpose is spreading the spores. The widespread infection led to a collapse of the social order in the Vault. By 2096, it was abandoned and a party of 118 survivors made way for the Zion Canyon. The dead eventually mutated into spore carriers or became stationary colonies of the fungus.
A body colonized by the fungus regresses to a feral state, as the colony warps it to make it a more effective spore carrier. This infection vector has green, wrinkled skin (reminiscent of a bark) with stiff, leaf-like protrusions on the back, allowing it to blend in with the foliage. The hands and feet possess only four digits and no fingernails. The body is also incredibly flexible and agile.
The spore carrier will typically lay dormant among vegetation. However, once a threat is detected, it will rise out of its slumber and attack ferociously, exhibiting similar behavior to a feral ghoul. It may also spontaneously spray irradiated spores to further damage and infect the target of its attack.
Spore carriers are quick and use melee attacks. Spore carriers share some characteristics with the trogs from the Fallout 3 add-on The Pitt. 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 Courier's compass, nor be targeted via V.A.T.S. until they move.
Spore carriers are also known for sneaking up on their victim. However, their health meter will become visible if they are injured by an area-of-effect weapon, like a flamer or grenade, immediately revealing their presence.
Upon detecting an intruder, the spore carrier will raise themselves out of the large patch of vegetation where they hide and will let off a growl in a similar manner to that of a feral ghoul, but with greater ferocity.
While a spore carrier is getting up or sleeping, attackers in sneak mode who manually attack the spore carrier will get a critical.
Spore carrier brutes are found in the same areas other spore carriers are found, and usually tend to act the same. However, brutes tend to be more aggressive, and are tougher and larger than regular spore carriers. A brute's spore burst does equal damage to a regular spore carrier.
Runts are the smallest and weakest of the spore carrier family. However, they are still quite fast and may overwhelm an unaware, low leveled character. Also, a runt's spore burst is equally as damaging as a regular variant's.
The spore carrier beast is only found in Zion Canyon in the Honest Hearts add-on. They are faster, stronger, larger and more dangerous than any of the other spore carriers and are often found around spore plants.
Beauveria is a genus of fungi typically known to parasitically infect insects. Beauveria mordicana seems similar in effects to the entomopathogenic fungus cordyceps unilateralis, which assumes control of the infected organism's immune system and continues to grow post-mortem.
↑Old World Blues endings: "The Biological Research Station, obsessed with seeding everything in sight, requested a transfer to the X-22 Botanical Garden... so that it might, in its own words, "sensually fertilize the garden's smooooth contours." The Garden sent back a polite refusal, saying it had prior commitments with a Vault it had helped infect before the war."